On this page
Quick Reference
Overview and Recommendations
Background
- •Bronchiolitis is an acute viral lower respiratory tract infection in infants <2 years, characterized by inflammation, mucus plugging, and bronchiolar obstruction, most commonly caused by (RSV). It is the leading cause of hospitalization in US infants <1 year, accounting for over 149,000 admissions annually and $543 million in direct costs, though the majority of cases (87%) are managed in primary care.
- •The pathophysiology centers on viral infection of the airway epithelium, leading to epithelial necrosis, neutrophil infiltration, and sloughed debris that obstruct small airways. The host immune response, particularly a >200-fold elevation of IL-6, drives the most severe outcomes, including rapid deterioration and brain edema in fatal cases.
- •Risk factors for severe disease include age <2 months, preterm birth, congenital heart disease, chronic lung disease, immunodeficiency, siblings aged 0-3 years, low income, and neighborhood deprivation. The strongest predictor is the presence of any comorbidity (OR 5.33).
- •The clinical course follows a catarrhal phase (rhinorrhea, cough, low-grade fever) over 1-2 days, then a respiratory distress phase (tachypnea, wheezing, hypoxemia) peaking at days 3-5, followed by gradual recovery. Apnea may be the sole presenting sign in infants <2 months.
- •Bronchiolitis is defined as the first episode of wheezing in an infant <2 years; recurrent wheezing episodes should be labeled as asthma or recurrent viral wheeze, not bronchiolitis, to avoid unnecessary bronchodilator and corticosteroid use.
Evaluation
- •Suspect bronchiolitis in any infant <2 years presenting with acute onset of coryza (rhinorrhea, nasal congestion, cough) followed by lower respiratory signs: tachypnea, wheezing, crackles, and increased work of breathing.
- •Ask about the onset and progression of symptoms, fever, feeding intolerance (decreased oral intake, fewer wet diapers), apnea (especially in infants <2 months), and exposure to sick contacts or tobacco smoke.
- •Examine for vital signs: respiratory rate >50-60/min, heart rate >160/min, SpO₂ <90% (or <87% in ED predicts ICU admission). Assess work of breathing, subcostal, intercostal, suprasternal retractions, nasal flaring, head bobbing, grunting. Auscultate for diffuse crackles and expiratory wheezes; in severe disease, breath sounds may be diminished due to air trapping.
- •The gold-standard diagnostic test is clinical diagnosis: no laboratory or imaging test is required for confirmation in typical cases. The diagnosis rests on the presence of acute-onset lower respiratory illness with coryzal prodrome, tachypnea, and crackles/wheeze in a child ≤23 months.
- •Do not routinely order chest radiography, it does not change management and increases antibiotic use. Reserve CXR for atypical presentations (suspected foreign body, pneumonia, atelectasis) or severe disease requiring ICU admission.
- •Do not routinely obtain viral testing (e.g., RSV PCR), it does not alter management or outcomes. It may be used for cohorting hospitalized infants to prevent nosocomial spread, but this is a public health decision.
- •Do not routinely obtain complete blood count, blood cultures, or inflammatory markers, they have no clinical utility in typical bronchiolitis. Procalcitonin and CRP may have some benefit in predicting bacterial co-infection in ICU patients, but evidence is very low.
- •Consider urinalysis and urine culture only if there is clinical suspicion for UTI; the prevalence of concomitant UTI is only 3.1%, and drops to 0.8% when pyuria or nitrites are present, below recommended testing thresholds.
- •Consider differential diagnoses: asthma (recurrent wheezing, older age, family atopy), (sudden choking, unilateral wheeze), (focal crackles, high fever, consolidation on CXR), (paroxysmal cough with whoop, post-tussive emesis, apnea, no fever), congenital heart disease (cyanosis, murmur, hepatomegaly).
- •Use a severity score to objectify assessment: the (RDAI) (0-17) incorporates retractions, wheezing, and respiratory rate; the (0-12) includes respiratory rate, retractions, accessory muscles, and auscultation. Both have good interrater reliability but considerable measurement error (RDAI limits of agreement ±3.8 points), use the trend over 4-6 hours, not a single value.
- •Risk stratify for severe outcomes: predictors of ICU admission include age <2 months, heart rate >160/min, SpO₂ <87%, previous ICU admission, and time of onset ≤2 days. The shows the highest discrimination for in-hospital mortality (AUROC 0.83) in resource-limited settings.
- •In infants with comorbidities (prematurity, congenital heart disease, chronic lung disease, immunodeficiency), maintain a lower threshold for admission and escalation, odds of critical care admission or death after ED discharge are 5-fold higher.
Management
- •Initiate supportive care as the cornerstone: oxygen therapy to maintain SpO₂ ≥90% (low-flow nasal cannula ≤2 L/min first-line), nasal suctioning (enhanced suctioning may reduce additional resource use), and hydration (enteral if safe, otherwise IV isotonic fluids).
- •For mild disease (no hypoxia, mild respiratory distress, adequate feeding), manage at home with parental education on signs of deterioration and expected duration of cough (up to 3 weeks). Do not prescribe bronchodilators, corticosteroids, or antibiotics.
- •For moderate disease (hypoxia, tachypnea, retractions, feeding difficulty), admit to hospital. Start low-flow oxygen; if fails, escalate to (HFNC) at 1 L/kg/min (max 20 L/min, FiO₂ to target SpO₂ ≥90%). HFNC reduces treatment failure compared to standard oxygen (RR 0.50, 95% CI 0.40-0.62) and lowers escalation to mechanical ventilation.
- •For severe disease (persistent hypoxia, apnea, marked respiratory distress, inability to feed), admit to ICU. HFNC is preferred over bubble CPAP as initial noninvasive support (lower treatment failure 23.7% vs 42.4%; RR 0.56). If HFNC fails, consider CPAP at 5-8 cm H₂O; use helmet interface for better tolerance (failure due to intolerance 17% vs 54% with mask).
- •Mechanical ventilation is reserved for severe respiratory failure, apnea, or impending respiratory failure. Use lung-protective strategies with PEEP 5-8 cm H₂O.
- •Do not routinely use bronchodilators (albuterol, salbutamol, epinephrine), they do not improve oxygen saturation, reduce admission, or shorten length of stay (Cochrane meta-analysis of 30 trials, 1992 infants).
- •Do not routinely use corticosteroids (systemic or inhaled), they are ineffective in reducing hospital admission or length of stay. In the ICU, the combination of systemic corticosteroids and inhaled epinephrine may reduce duration of positive pressure support (geometric mean 26 vs 40 hours; adjusted ratio 0.66), but this is not recommended outside intensive care.
- •Do not use hypertonic saline nebulization, it does not reduce hospital admission (adjusted risk difference -3.2%) and causes more cough. In hospitalized infants, evidence is conflicting: Cochrane meta-analysis shows a modest reduction in LOS (MD -0.41 days), but reanalysis adjusting for heterogeneity found no effect.
- •Do not use antibiotics unless there is proven bacterial co-infection, antibiotic overuse is common (34-99% of cases) despite no benefit.
- •Do not use chest physiotherapy, chest percussion, or postural drainage, they have no effect on length of stay.
- •Do not routinely use caffeine citrate for apnea, a single dose of 25 mg/kg does not reduce apnea episodes or need for ventilation.
- •Antiviral therapy: (RSV fusion inhibitor) 10-40 mg twice daily for 5 days based on weight improved Wang score by day 3 (difference -0.8 points, p=0.002) in a phase 3 trial, but resistance-associated mutations emerged in 9% of recipients. It is not yet standard of care.
- •Prevention: administer (single intramuscular dose) to all infants <8 months entering their first RSV season, real-world effectiveness ~74% reduction in RSV hospitalizations. For high-risk infants (e.g., congenital heart disease, chronic lung disease, preterm <29 weeks), palivizumab 15 mg/kg IM monthly during RSV season remains an option but is largely superseded by nirsevimab.
- •Monitor serial clinical severity scores, heart rate, respiratory rate, SpO₂, and feeding ability. Escalate if: persistent tachypnea, SpO₂ <90% despite oxygen, worsening work of breathing, or apnea.
- •Discharge criteria: stable SpO₂ ≥90% in room air, adequate oral feeding (≥75% of usual volume), no significant respiratory distress, and reliable caregiver support. Home oxygen therapy is a feasible alternative to prolonged hospitalization for selected infants, reducing hospital bed-days by nearly 2 days.
- •Counsel families: cough may persist for 2-3 weeks; avoid smoke exposure; hand hygiene and breastfeeding are protective; return if signs of respiratory distress (grunting, nasal flaring, retractions, poor feeding, lethargy). Home pulse oximetry is not recommended as desaturations are common and do not predict unscheduled visits.
Board Review — High Yield
- •First episode of wheezing in infant <2 years, key definition: recurrent wheezing is not bronchiolitis.
- •RSV is the most common cause, responsible for 70-80% of hospitalized cases.
- •Apnea can be the presenting sign in infants <2 months, even without wheezing.
- •No routine testing, diagnosis is clinical; chest X-ray and viral testing are not recommended.
- •HFNC reduces treatment failure, 1 L/kg/min initial flow; avoid >6 L/min due to air leak risk.
- •Corticosteroids and bronchodilators are ineffective, do not use routinely.
- •Nirsevimab prevents RSV hospitalization, single dose, 74% effectiveness.
- •Most common complication is post-bronchiolitis wheezing, 1 in 5 hospitalized infants have subsequent respiratory admission by age 5.
- •RDAI score, most validated severity score; use trend not single value.
- •Maternal RSV vaccination emerging but not yet standard.
Deep Dive — Evidence Details
Definition, Classification & Nomenclature
- ▸Bronchiolitis is a clinical syndrome in young children, but published studies use variable age and diagnostic criteria; the relevant definition must be stated explicitly [13][14][285][286][289][292][297].
- ▸RSV-LRTI and RSV-associated bronchiolitis overlap but are not synonymous, and agreement among case definitions is imperfect [292].
- ▸Severity scores lack a universally accepted standard; severity should be described using clinical status and respiratory-support requirements [285][298].
- ▸Bronchiolitis obliterans and post-HSCT bronchiolitis obliterans syndrome are distinct chronic or transplant-associated entities and must not be conflated with acute infant bronchiolitis [8].
- ▸Pathogen, age, complications, and diagnostic criteria should accompany the term bronchiolitis in clinical and research reporting [74][287][294].
Scope and terminology
“Bronchiolitis” is used primarily for an acute lower-respiratory illness in infants and young children, but the supplied literature does not identify one universally accepted case definition. Published studies variably enroll children aged <12 months, <2 years, 1–23 months, or ≤24 months, and some studies include broader pediatric age ranges when evaluating respiratory syncytial virus (RSV) or all-cause bronchiolitis [13]A1a[14]B2a[285][286]C[289][292]C[297]. Consequently, the term should be interpreted together with the patient’s age, clinical findings, suspected or confirmed pathogen, and study-specific eligibility criteria [285][286]C[292]C.
In this section, acute bronchiolitis denotes the clinical syndrome studied in infants and young children with acute respiratory illness, usually in the context of viral infection. Viral bronchiolitis is used when the illness is clinically diagnosed as bronchiolitis and attributed to a viral cause; RSV is the most extensively studied pathogen in the cited literature [285][286]C[289][297]. RSV lower respiratory tract infection (RSV-LRTI) is related but not synonymous terminology: a multinational prospective study evaluated several RSV-LRTI definitions against the WHO 2015 definition and found that agreement between definitions varied, demonstrating that diagnostic criteria influence case ascertainment [292]C.
Clinical classification of acute bronchiolitis
A practical classification is based on the clinical context rather than on a single validated score:
| Classification | Definition or distinguishing feature | Evidence |
|---|---|---|
| Acute viral bronchiolitis | Clinically diagnosed acute bronchiolitis in a young child, with viral attribution where established; RSV is a major study focus | [285][289][297] |
| RSV-associated bronchiolitis or RSV-LRTI | Bronchiolitis or lower-respiratory infection associated with laboratory-confirmed or clinically defined RSV; definitions differ across studies | [285][286]C[292]C |
| Bronchiolitis with apnea | Bronchiolitis complicated by bronchiolitis-related apnea in children aged <12 months; caffeine and other methylxanthines have been studied specifically in this subgroup | [13]A1a |
| Severe or critical bronchiolitis | Bronchiolitis requiring intensive respiratory support or intensive care; studies have examined high-flow nasal cannula, noninvasive ventilation, invasive ventilation, and intensive-care admission | [14]B2a[110]B3b[296][298] |
| Bronchiolitis with concurrent serious bacterial infection | Bronchiolitis accompanied by bacteremia, urinary tract infection, or another serious bacterial infection; this is a complication or coexisting diagnosis, not a separate bronchiolitis phenotype | [297] |
Severity should not be inferred from a single respiratory score. A systematic review found multiple RSV and bronchiolitis severity scores but no overall consensus regarding the most clinically useful score [285]. The classification “severe” should therefore be anchored to the complete clinical picture and support requirements, with explicit documentation of oxygenation, respiratory effort, apnea, feeding or hydration impairment, and escalation of respiratory support when those data are available [285][298].
Etiologic and epidemiologic nomenclature
“RSV bronchiolitis” identifies bronchiolitis associated with RSV, whereas “all-cause bronchiolitis” includes bronchiolitis attributed to any cause or without pathogen confirmation [286]C. The distinction matters because mortality analyses have reported separate outcomes for RSV and all-cause bronchiolitis, and because the evidence base is dominated by hospitalized children rather than otherwise healthy community cases [286]C.
Other viruses may be associated with the same clinical syndrome. In a Spanish hospitalized cohort, only 1.8% of children admitted with SARS-CoV-2 infection met the study’s bronchiolitis criteria, and the investigators concluded that SARS-CoV-2-associated acute bronchiolitis was neither frequent nor more severe in that cohort [294]C. This finding supports retaining a clinical syndrome label while specifying the detected virus, rather than assuming that all viral bronchiolitis is RSV-related [294]C.
“Bronchiolitis” should also be distinguished from later respiratory diagnoses. Asthma definitions after early-life bronchiolitis vary substantially; one cohort compared broad, epidemiologic, and definitions incorporating bronchodilator response, illustrating that post-bronchiolitis asthma is an outcome or subsequent diagnosis rather than a synonym for bronchiolitis [288]. Genetic and longitudinal studies likewise examine asthma risk after viral bronchiolitis, not an alternative definition of the acute illness [293][296]. Bronchiolitis has also been used as one component of broader late-respiratory-disease outcome definitions in preterm infants, alongside bronchopulmonary dysplasia, asthma, reactive airway disease, and pneumonia [290].
Bronchiolitis obliterans and bronchiolitis obliterans syndrome
Bronchiolitis obliterans (BO) and bronchiolitis obliterans syndrome (BOS) are distinct nomenclatural entities from acute infant bronchiolitis. The 2024 American Thoracic Society guideline addresses BOS after pediatric allogeneic hematopoietic stem-cell transplantation (HSCT), where BOS is identified as the most common noninfectious pulmonary complication after HSCT and requires a separate surveillance and detection framework [8]A1c. Thus, “acute bronchiolitis,” “RSV-LRTI,” “BO,” and “post-HSCT BOS” should not be used interchangeably [8]A1c[292]C.
Diagnostic and reporting principles
A report should specify age, clinical syndrome, pathogen status, severity, and any major complication or special context. Definitions should be quoted or operationalized when comparing studies because variation in diagnostic criteria can change prevalence estimates and apparent outcomes [287][292]C. Cough-sound machine-learning studies may support future objective classification of pediatric acute respiratory diseases, but the cited systematic review describes predictive research rather than an established clinical bronchiolitis definition [74]B2a. Quality-improvement studies likewise evaluate adherence to care practices—including avoidance of routine chest radiography, salbutamol, glucocorticoids, antibiotics, and epinephrine—rather than redefining bronchiolitis itself [10]B2b[295]. Studies of HFNC have additionally demonstrated substantial variation in intervention description, supporting precise reporting of respiratory-support terminology without treating HFNC use as a diagnostic criterion [14]B2a.
| Term | Recommended interpretation | Citation |
|---|---|---|
| Acute bronchiolitis | Acute clinical bronchiolitis syndrome in infants or young children | [13]A1a[14]B2a[285] |
| Viral bronchiolitis | Acute bronchiolitis with viral attribution or investigation | [285][289] |
| RSV-LRTI | RSV-associated lower-respiratory infection defined using specified criteria; not automatically equivalent to bronchiolitis | [292]C |
| All-cause bronchiolitis | Bronchiolitis regardless of pathogen or with no pathogen identified | [286]C |
| Bronchiolitis obliterans/BOS | Distinct obstructive bronchiolar disease; BOS after pediatric HSCT requires dedicated surveillance terminology | [8]A1c |
Pathophysiology & Developmental Mechanism
- ▸Infant bronchiolitis results from viral epithelial injury superimposed on developmentally limited small-airway and lung reserve, with prematurity, bronchopulmonary dysplasia, congenital heart disease, Down syndrome, and reduced baseline lung function increasing vulnerability.[24][27][29][305]
- ▸RSV-associated epithelial necroptosis and HMGB1 release may amplify airway inflammation and obstruction.[307]
- ▸PGD2–DP2 signaling suppresses interferon-λ and promotes severe viral bronchiolitis in experimental models, while also linking acute disease to later asthma susceptibility.[300]
- ▸Neonatal regulatory B cells can become RSV-infected through CX3CR1, produce IL-10, dampen Th1 responses, and correlate with severe disease.[311]
- ▸Endothelial and neutrophil activation are associated with respiratory-support requirements in infants with acute bronchiolitis.[301]
- ▸RSV-associated pulmonary hypertension involves ST2 signaling in neonatal mouse models and is clinically important, especially with congenital heart disease.[28][308]
- ▸Prenatal tobacco smoke, maternal environmental exposures, atopic predisposition, and excess adiposity may modify severity, but much of the evidence is observational or experimental rather than causal.[25][27][299][310]
Overview
Bronchiolitis is an acute lower-airway disease of infancy, most commonly caused by respiratory syncytial virus (RSV), in which infection of the airway epithelium produces bronchiolar inflammation, epithelial injury, secretions, and airflow obstruction.[24]C4[26]C4[29]D5[303]D RSV reaches the lower respiratory tract after an incubation period of approximately 4–6 days and has a recognized tropism for airway epithelial cells.[26]C4 Viral replication can be extensive in the bronchioles by approximately 4 days after infection, with bronchiolar lesions reported in a neonatal lamb model that shares important developmental, structural, physiologic, cellular, and immunologic features with human infants.[29]D5
Developmental susceptibility of the infant lung
The severity of bronchiolitis reflects an interaction between viral injury and the immature infant respiratory system.[27]D5[29]D5 Prematurity and bronchopulmonary dysplasia are established risk factors for severe RSV disease, and congenital heart disease and Down syndrome are associated with increased mortality or prolonged morbidity.[24]C4[29]D5 Reduced baseline lung function related to prematurity or congenital airway abnormalities may increase susceptibility to RSV infection and amplify the consequences of small-airway inflammation.[29]D5[305]D Prenatal environmental exposures may also influence this vulnerability because fetal lung development can be modified during critical developmental windows by maternal infection, pollutants, and nutritional factors.[27]D5
Maternal tobacco exposure is a potential developmental modifier of antiviral host defense. In a neonatal mouse model, in-utero tobacco-smoke exposure altered lung inflammation, viral clearance, and CD8+ T-cell responses after RSV infection; human epidemiologic observations also associate prenatal or passive smoke exposure with greater susceptibility to respiratory viral disease.[310]D These findings support an effect on structural and immunologic defenses, but they do not establish that tobacco exposure is a direct cause of severe bronchiolitis in individual infants.[310]D
Atopic predisposition may begin before birth. In a prospective nested cohort of 5,407 children, the association between atopic dermatitis and hospitalization for severe bronchiolitis was specifically examined, reflecting the possibility that early atopic disease contributes to susceptibility or identifies a shared immune phenotype.[25]B2b The available study evidence supports an epidemiologic association question rather than a definitive mechanistic pathway.[25]B2b
Airway epithelial injury and innate inflammation
RSV infection causes airway epithelial-cell death, and experimental evidence identifies necroptosis as one mechanism of epithelial injury.[307]D RSV-infected human airway epithelial cells and neonatal mice demonstrated activation of receptor-interacting protein kinase 1 and mixed-lineage kinase domain-like pathways, with release of the damage-associated molecule HMGB1; these findings link epithelial necroptosis to inflammatory amplification in RSV bronchiolitis.[307]D The resulting epithelial damage can plausibly worsen mucosal obstruction and impair airway defense, although the cited studies do not quantify the relative contribution of necroptosis to clinical severity in all infants.[307]D
RSV also activates lipid-mediated type 2 inflammatory pathways. In cultured human airway epithelial cells, RSV increased hematopoietic prostaglandin D synthase expression and PGD2 release, while PGD2 concentrations were higher in nasopharyngeal samples from young infants hospitalized with RSV bronchiolitis than in healthy controls.[300] Signaling through the PGD2/DP2 receptor promotes severe viral bronchiolitis partly by suppressing interferon-λ production; in a neonatal mouse model, DP2 antagonism reduced viral load, immunopathology, and morbidity and prevented the model’s later predisposition to asthma.[300] These findings identify PGD2–DP2 signaling as a mechanistic bridge between acute viral inflammation and post-bronchiolitis airway disease, but the therapeutic implications remain based on experimental evidence.[300]
Neonatal regulatory B cells may further shape the antiviral response. Human neonatal regulatory B cells produce interleukin-10 after RSV exposure, interact with RSV fusion protein F, upregulate CX3CR1, and can be infected through interaction between CX3CR1 and the viral glycoprotein G.[311]D Their interleukin-10 production dampens T-helper-1 cytokine responses, and the frequency of RSV-infected neonatal regulatory B cells in the respiratory tract of infants with severe acute bronchiolitis correlated with disease severity.[311]D
Vascular, neutrophilic, and cardiopulmonary mechanisms
Severe bronchiolitis involves more than airway obstruction. In a clinical study of 34 infants with bronchiolitis and 8 controls, markers of pulmonary vascular endothelial activation—including angiopoietin-1, angiopoietin-2, soluble P-selectin, soluble E-selectin, soluble VCAM-1, and soluble ICAM-1—and leukocyte counts were evaluated in relation to respiratory-support requirements.[301] The study linked endothelial and neutrophil activation with the need for respiratory support and its duration, supporting a contribution from vascular inflammation and innate leukocyte recruitment to acute respiratory failure.[301]
Pulmonary hypertension can complicate moderate-to-severe RSV bronchiolitis and is particularly consequential in infants with congenital heart disease.[28]D5[308]D In neonatal mice infected with RSV at 5 days of age and reinfected 4 weeks later, pulmonary hypertension was evidenced by increased right-ventricular systolic pressure, shortened pulmonary-artery acceleration time, and a reduced acceleration-time/ejection-time ratio.[28]D5 Deficiency of suppression of tumorigenicity 2 (ST2) signaling ameliorated RSV-associated pulmonary hypertension in this model, implicating the ST2 pathway in vascular disease after infection.[28]D5
Systemic modifiers and long-term development
Excess adiposity may intensify illness after hospitalization. In a retrospective cohort of infants aged ≤24 months hospitalized with bronchiolitis, increased adiposity was associated with longer hospital stays; the study evaluated BMI z score and ponderal index and also examined the risk of pediatric intensive-care transfer.[299] The proposed biological rationale is that excess adiposity increases proinflammatory adipokines implicated in bronchiolitis pathogenesis, although the observational design cannot prove causation.[299]
Severe bronchiolitis is associated with increased later risk of childhood asthma, and experimental PGD2–DP2 signaling provides one potential mechanism for this developmental transition.[25]B2b[300] Prenatal viral or environmental influences may additionally alter lung structure and airway-control systems before clinical disease emerges.[27]D5 Rare reports suggest that RSV may spread hematogenously and potentially transplacentally: RSV has been detected at birth in a newborn with respiratory distress, and the case was considered strongly suggestive of prenatal transmission.[26]C4 However, this represents case-level evidence and should not be generalized to typical postnatal bronchiolitis.[26]C4 Evidence concerning porcine hemagglutinating encephalomyelitis virus relates to respiratory lesions in pigs rather than human bronchiolitis and does not inform the developmental mechanism of infant RSV disease.[302]
| Domain | Proposed mechanism | Evidence |
|---|---|---|
| Developmental lung vulnerability | Prematurity, bronchopulmonary dysplasia, airway abnormalities, and immature respiratory reserve increase consequences of bronchiolar inflammation. | Human risk observations and lamb-model data.[24]C4[29]D5[305]D |
| Epithelial injury | RSV-associated necroptosis activates RIPK1/MLKL pathways and releases HMGB1. | Human airway-cell and neonatal-mouse studies.[307]D |
| Type 2 lipid signaling | PGD2–DP2 signaling suppresses interferon-λ and increases viral immunopathology. | Human samples and neonatal-mouse model.[300] |
| Neonatal immune regulation | RSV infects neonatal regulatory B cells through CX3CR1 and induces IL-10-mediated Th1 suppression. | Human neonatal and severe-disease observations.[311]D |
| Vascular inflammation | Endothelial activation and neutrophil responses associate with respiratory-support needs. | Infant clinical study.[301] |
| Pulmonary vascular disease | RSV reinfection produces pulmonary hypertension involving ST2 signaling. | Neonatal-mouse studies.[28]D5[308]D |
Epidemiology, Etiology & Risk Factors
- ▸RSV is the leading cause of bronchiolitis in children younger than 24 months and a major cause of infant lower-respiratory-tract disease. [55][315]
- ▸The global RSV evidence base includes 539 studies and 584 datasets, but the supplied abstract does not provide the pooled prevalence estimate. [51]
- ▸In Chinese children aged 0–14 years, pooled HMPV detection was 4.56%, peaking at 6.02% in 1-year-olds, with no important sex difference reported. [52]
- ▸Prematurity, young age, viral type or coinfection, and environmental exposures are clinically relevant considerations, although several supplied studies do not report bronchiolitis-specific adjusted risk estimates. [52][54][312][313]
- ▸Nirsevimab introduction and regional implementation may alter bronchiolitis diagnoses, hospitalizations, and healthcare utilization; the supplied abstracts describe these evaluations without providing all effect estimates. [55][321][324]
Epidemiology
Acute bronchiolitis is predominantly an illness of infancy and early childhood. Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis in children younger than 24 months and is a major driver of emergency-department visits, hospitalizations, and pediatric intensive-care admissions. [55]B2b RSV is also described as the leading cause of lower-respiratory-tract infection in infants and as one of the leading causes of lower-respiratory illness and hospitalization in children aged ≤5 years worldwide. [315][325] In a regional Italian hospital network, bronchiolitis admissions were assessed in children aged 0–2 years, underscoring the concentration of clinically significant disease in this age range. [322]C
The burden is seasonal and healthcare utilization varies according to surveillance setting, viral circulation, and public-health interventions. A Polish multicenter study collected data during the 2022–2023 RSV season from 41 hospitals and characterized RSV-associated admissions among children aged ≤5 years. [325] A single-center Italian emergency-department cohort compared two consecutive RSV seasons, from 1 October to 30 April in 2023–2024 and 2024–2025, to assess bronchiolitis epidemiology after nirsevimab introduction. [55]B2b In Italy, nirsevimab was introduced in Europe in late 2022 and was widely implemented in some regions during 2024; implementation was regionally variable. [321][324] Studies in Lazio and Veneto evaluated whether this intervention changed bronchiolitis diagnoses, hospitalizations, and primary-care utilization, but the supplied evidence does not provide the corresponding effect estimates. [321][324]
Etiology
RSV is the principal viral etiology of infant bronchiolitis, but bronchiolitis is etiologically heterogeneous. A global systematic review and meta-analysis included 539 studies and 584 datasets of polymerase-chain-reaction-confirmed respiratory infections in children younger than 18 years and evaluated hRSV prevalence and its association with pediatric respiratory-tract infection across regions, ages, care settings, sampling periods, disease categories, genotypes, and subtypes. [51]B2a The available abstract confirms the breadth of the evidence base but does not report the pooled prevalence or the association estimate in the supplied material. [51]B2a
Human metapneumovirus (HMPV) is another recognized viral contributor. A Chinese systematic review and meta-analysis of 78 studies, comprising 334,901 children aged 0–14 years, identified 15,612 HMPV-positive participants and reported an overall detection rate of 4.56% (95% CI, 3.83%–5.43%). [52]B2a Detection was highest in 1-year-olds: 6.02%. [52]B2a The analysis found no meaningful sex difference in detection, with reported rates of 4.93% in boys and 4.86% in girls. [52]B2a
Other respiratory viruses may cause bronchiolitis or bronchiolitis-like lower-respiratory disease. In a critical-bronchiolitis PICU cohort, investigators compared nasal inflammatory responses among children with RSV, rhinovirus, and polyviral infection, indicating that pathogen type and coinfection are relevant biological variables in severe disease. [312]C Influenza, parainfluenza, and HMPV were also included among viral causes of lower-respiratory-tract infection requiring hospitalization in a population-level comparison with RSV. [315] Adenovirus was investigated in a binational study of severe acute respiratory infection in hospitalized children in Brazil and Colombia; an adenovirus outbreak occurred in both regions in late 2022, although the supplied abstract does not establish adenovirus as a common cause of routine bronchiolitis. [318]
Risk factors for severe disease and healthcare use
Young age is the clearest epidemiological risk marker. RSV-associated disease is concentrated in infants, and HMPV detection in the Chinese meta-analysis was highest at age 1 year. [52]B2a[55]B2b Prematurity and neonatal respiratory vulnerability are additional clinically important considerations. A prospective cohort of infants born before 32 weeks’ gestation evaluated bronchopulmonary dysplasia and longer-term respiratory morbidity in relation to human-milk exposure, reflecting the increased baseline respiratory risk of very preterm infants; the supplied abstract does not provide bronchiolitis-specific effect estimates. [313]
Host inflammatory biology may influence severity. A prospective PICU study of 42 children with critical bronchiolitis and nine healthy controls examined cytokine responses and their relationship to viral type and clinical risk factors, but the supplied evidence does not identify which individual host factors independently predicted critical illness. [312]C Children with previous severe viral lower-respiratory infection may also generate substantial subsequent healthcare needs; a nationwide Israeli cohort compared infants hospitalized before 12 months with PCR-confirmed RSV lower-respiratory infection against those with other respiratory viruses and assessed later asthma-related utilization. [315]
Environmental and maternal exposures are potential modifiers of risk. A prospective Singapore birth cohort followed 1,124 mother–child pairs from 2009 to 2019 and assessed monthly meteorological conditions, outdoor air quality, ozone, maternal factors, and individual characteristics from the in-utero period through age 8 years in relation to first bronchiolitis, wheeze, and eczema. [54]B2b Because the supplied abstract does not report the adjusted associations, these exposures should be regarded as investigated risk factors rather than established independent causes. [54]B2b
Epidemiological interpretation
Observed bronchiolitis rates are influenced by age structure, season, diagnostic definitions, testing practices, healthcare access, viral circulation, and prophylaxis coverage. [51]B2a[52]B2a[55]B2b[321][324] Primary-care and hospital populations are not interchangeable: a Spanish regional analysis of pediatric respiratory-infection consultations found a younger mean age in hospital care (3.4 years) than in primary care (8.7 years), although the study was not limited to bronchiolitis. [316] Similarly, evidence concerning bronchiolitis obliterans syndrome after hematopoietic-cell transplantation, pulmonary deficits after childhood leukemia, or respiratory failure from structural airway disease describes distinct conditions and should not be conflated with epidemiology of acute infectious bronchiolitis. [46]C4[56]B2b[320]
| Evidence domain | Population or design | Findings relevant to bronchiolitis |
|---|---|---|
| RSV | Global systematic review and meta-analysis | 539 studies and 584 datasets; PCR-confirmed pediatric respiratory infections; subgroup analyses included age, region, care setting, disease category, genotypes, and subtypes. [51]B2a |
| HMPV | Chinese systematic review and meta-analysis | 78 studies; 334,901 children aged 0–14 years; 15,612 positive; pooled detection 4.56% (95% CI 3.83%–5.43%); highest detection in 1-year-olds, 6.02%. [52]B2a |
| Environmental exposures | Singapore prospective birth cohort | 1,124 mother–child pairs followed from 2009–2019; meteorology, ozone, air quality, maternal, and individual exposures assessed against first bronchiolitis through age 8 years. [54]B2b |
| Prevention and utilization | Italian regional and hospital studies | Studies evaluated nirsevimab-associated changes in bronchiolitis diagnoses, admissions, emergency care, and primary-care contacts during RSV seasons. [55]B2b[321][324] |
Clinical Presentation
- ▸Bronchiolitis predominantly affects infants, with severe disease commonly studied in children younger than 12 months and hospitalized RSV disease in those aged 1–24 months.[34][289][328]
- ▸Cough and dyspnea are common clinical features; dyspnea is associated with oxygen requirement in hospitalized RSV infection.[74][335]
- ▸Severity markers include hypoxemia or oxygen requirement, respiratory failure, pneumonia, escalating respiratory support, PICU admission, and shock.[335][337][68]
- ▸Higher-risk features include age ≤3 months, prematurity, RSV-season birth, and prenatal tobacco-smoke exposure.[335]
- ▸Fever becomes more prevalent with increasing age during infancy and should not be used alone to confirm or exclude bronchiolitis.[336]
- ▸Bronchiolitis overlaps clinically with pneumonia, asthma or reactive airway disease, and other respiratory disorders; diagnostic reassessment is required when the course or examination is atypical.[65][329][330][332][333]
Typical age and setting
Bronchiolitis is principally an illness of infancy. The contemporary hospitalized RSV evidence base includes infants and young children aged 1–24 months, while studies of severe bronchiolitis commonly define the population as infants younger than 12 months or children aged 1–23 months.[34]A1b[328][289] RSV infection occurs in almost all infants by the second year of life, although clinical severity varies substantially.[334] RSV is strongly associated with a bronchiolitis diagnosis in primary care, although it may also present as bronchitis.[326] Hospitalization represents the severe end of the spectrum; severe bronchiolitis has been defined in prospective infant cohorts as bronchiolitis requiring hospital admission.[327]
Respiratory symptoms and signs
Cough is a common symptom of acute respiratory disease in children, and cough-sound characteristics may contain information useful for distinguishing respiratory conditions; however, machine-learning cough analysis remains an investigational aid rather than a replacement for clinical assessment.[74]B2a In hospitalized RSV cohorts, dyspnea is an important clinical feature and is associated with the need for supplemental oxygen therapy.[335] The clinical spectrum may extend to hypoxemia, pneumonia, respiratory failure, intensive care admission, and prolonged hospitalization.[335] In critically ill children, bronchiolitis may require escalation of respiratory support, including high-flow nasal cannula (HFNC), and some patients receive intensive respiratory therapies such as continuous inhaled epinephrine through HFNC.[331]C[337]
Clinical severity should therefore be judged by the overall respiratory trajectory rather than by a single symptom. Relevant observed features include increased work of breathing or dyspnea, oxygen requirement, the need for escalating respiratory support, and deterioration requiring PICU-level care.[331]C[335][337] In a PICU cohort of children with RSV bronchiolitis, septic shock was considered a severe complication for which early risk recognition was clinically important.[68]B2b
Fever and age-related variation
Fever is not uniformly expressed across infancy in RSV bronchiolitis. A prospective study found that fever prevalence increased strongly with age, indicating age-related heterogeneity in the clinical phenotype.[336] Consequently, the absence of fever should not be used alone to exclude RSV bronchiolitis in a young infant, and fever should not by itself distinguish bronchiolitis from other respiratory infections.[336][326]
Risk markers for severe presentation
Younger age, particularly ≤3 months, prematurity, and being born during the RSV season were associated with greater severity among children hospitalized with laboratory-confirmed RSV infection.[335] Prenatal tobacco-smoke exposure was also associated with severe outcomes; exposure from both parents and from the father was reported as a risk factor in the cohort.[335] Dyspnea was a particularly important marker, with an association with oxygen therapy reported in hospitalized children.[335] A systematic review of Australasian infants identified risk factors for severe bronchiolitis and synthesized their relationship with prolonged hospitalization and PICU admission, although the strength and certainty of individual associations varied across observational studies.[328]
Severe bronchiolitis in infancy is also clinically important beyond the acute admission. In a multicentre prospective cohort, severe bronchiolitis was investigated in relation to asthma development by age 6 years, and nasal-airway microRNA profiles during hospitalization were associated with subsequent asthma risk.[327] These molecular findings are prognostic research signals and are not established bedside diagnostic criteria.[327]
Diagnostic boundaries and important mimics
Bronchiolitis can be difficult to distinguish from other lower-respiratory-tract diagnoses because clinical features overlap with asthma or reactive airway disease and pneumonia.[65]B2b Misclassification as pneumonia is particularly relevant in settings using clinical pneumonia definitions; a prospective Bangladeshi study specifically evaluated infants labeled as having World Health Organization–classified pneumonia because viral bronchiolitis may present with closely related manifestations.[329] Conversely, pneumonia and severe adenoviral disease can produce a bronchiolitis-like presentation; adenoviral pneumonia has been associated with plastic bronchitis, and diminished breath sounds were identified as a risk factor for that complication in one retrospective study.[332]
Other disorders should be separated from acute viral bronchiolitis according to age, history, examination, and course. Meconium aspiration syndrome is a neonatal disorder caused by aspiration of meconium-stained fluid and presents through airway obstruction, inflammation, and hypoxemia rather than the usual infant viral-bronchiolitis context.[330] Bronchiolitis obliterans syndrome and idiopathic pneumonia syndrome are described as post-allogeneic hematopoietic-stem-cell-transplant air-leak-related respiratory conditions and should not be conflated with acute viral bronchiolitis.[333]C
Practical severity assessment
At presentation, document age, prematurity, smoke exposure, symptom progression, dyspnea or work of breathing, fever, oxygenation, and the level and trajectory of respiratory support.[335][336] Particular concern is warranted when an infant is ≤3 months, requires supplemental oxygen, has worsening dyspnea, develops respiratory failure or shock, or needs HFNC/PICU escalation.[335][337][68]B2b These findings support a diagnosis of severe disease but do not establish a specific viral cause; RSV identification in the cited studies relied on laboratory testing, including molecular testing or other laboratory confirmation.[326][335]
| Feature | Clinical significance |
|---|---|
| Age ≤3 months | Associated with increased severity and oxygen-treatment requirement in hospitalized RSV infection.[335] |
| Prematurity | Associated with severe RSV outcomes.[335] |
| Prenatal tobacco-smoke exposure | Exposure from both parents or the father was associated with severe disease.[335] |
| Dyspnea or worsening work of breathing | Associated with oxygen requirement and may herald respiratory deterioration.[335] |
| Oxygen requirement, respiratory failure, or pneumonia | Indicates more severe lower-respiratory-tract disease.[335] |
| HFNC requirement or escalation to PICU | Signals clinically significant respiratory compromise.[331]C[337] |
| Shock or suspected septic shock | A potentially fatal complication in PICU patients with RSV bronchiolitis.[68]B2b |
Diagnosis & Workup
- ▸Bronchiolitis is diagnosed clinically; investigations should answer a specific question and should not replace serial bedside assessment [101].
- ▸Use chest radiography selectively for atypical disease, suspected complications, alternative diagnoses, or unexpected deterioration; do not obtain it routinely for uncomplicated presentations [101].
- ▸Lung ultrasound is a promising radiation-free adjunct, particularly when differentiating bronchiolitis from recurrent infection-associated wheeze, but current observational evidence does not establish it as a replacement for clinical diagnosis [340,346].
- ▸Viral testing should be selective and purpose-driven; RSV rapid testing evidence primarily concerns antibiotic-prescribing behavior, not a universal testing mandate [101,347].
- ▸Routine laboratory testing is unnecessary in typical stable disease; biomarkers and prediction models for septic shock apply to critically ill PICU populations, not routine bronchiolitis [68].
- ▸Accurate distinction from asthma or recurrent wheeze matters because combined bronchiolitis/asthma coding is associated with greater cost and resource utilization [343].
- ▸High-risk groups, including children with Down syndrome, warrant a lower threshold for observation and reassessment [341].
Clinical diagnosis
Acute bronchiolitis remains a clinical diagnosis based on the age-appropriate presentation of a first or usual episode of viral upper-respiratory symptoms followed by respiratory distress, tachypnea, increased work of breathing, wheeze and/or crackles, with or without hypoxemia. The available 2026 evidence continues to evaluate investigations as adjuncts to clinical assessment rather than replacements for bedside diagnosis [101]B2a. Diagnostic assessment should document respiratory rate, work of breathing, feeding and hydration, mental status, apnea, oxygen saturation, and the trajectory of illness because these findings determine the need for observation, admission, respiratory support, or escalation of care [101]B2a[109]B3b[322]C.
Severity assessment is particularly important in infants younger than 12 months, the population evaluated in a retrospective machine-learning study of bronchiolitis severity [109]B3b. That study used anamnestic and clinical variables available at admission to classify severity and compared its model with the Bronchiolitis Risk of Admission Score and the respiratory-severity-score/heart-rate measure; the investigators noted that existing severity scores may lack objectivity and may not reliably reflect clinical outcomes [109]B3b. Such tools should therefore supplement, not replace, repeated clinical reassessment [109]B3b.
Oxygenation and respiratory monitoring
Pulse oximetry is appropriate when hypoxemia or clinically significant respiratory distress is suspected, and serial assessment is more informative than a single measurement when the infant’s condition is evolving [101]B2a. The investigations review specifically examined diagnostic and management utility in hospitalized infants, including those with unexpected deterioration or intensive-care admission, indicating that the value of testing should be judged according to illness severity and clinical change [101]B2a. Infants requiring high-flow nasal cannula (HFNC) for moderate-to-severe bronchiolitis were the target population in the PROPOSITIS randomized trial; this trial evaluated whether prone positioning reduced escalation to noninvasive or invasive ventilation, making respiratory-support requirement a clinically important severity marker rather than a diagnostic test [339].
Chest radiography and lung ultrasound
Routine chest radiography should not be used automatically to confirm uncomplicated bronchiolitis. A 2026 overview of reviews and systematic review synthesized evidence on chest X-ray, laboratory testing, and viral testing in hospitalized infants, including severe cases; it identified 59 studies involving 23,605 infants across three systematic reviews and 27 observational studies, although the supplied abstract does not provide the final direction or certainty of each investigation-specific outcome [101]B2a. Chest radiography is best reserved for an atypical presentation, concern for an alternative diagnosis or complication, or unexpected clinical deterioration, with the indication documented [101]B2a.
Lung ultrasound (LUS) is an emerging radiation-free adjunct. In a prospective observational study of 338 children aged 1 month to 18 years with suspected lower-respiratory-tract infection, all participants underwent clinical assessment, chest radiography, and LUS at admission and follow-up; diagnostic performance, predictive values, accuracy, and agreement between modalities were compared [340]. Because that cohort included lower-respiratory-tract infections broadly rather than bronchiolitis alone, LUS findings should not be interpreted as definitive evidence of bronchiolitis without clinical correlation [340].
A separate multicentre prospective study evaluated LUS in children younger than 2 years with respiratory distress and infection-associated wheeze. LUS was performed within 24 hours of admission, scored from 0 to 4 across five lung areas, and summed to estimate pulmonary involvement; the primary diagnostic comparison was bronchiolitis versus recurrent wheezing triggered by lower-respiratory infection [346]. This supports LUS as a potential tool when the principal diagnostic problem is distinguishing bronchiolitis from recurrent wheeze or another lower-respiratory process, but the observational design does not establish that LUS should replace clinical assessment [346].
Viral and laboratory testing
Viral testing should be selective and linked to a clinical purpose, such as cohorting, infection-control decisions, epidemiologic surveillance, or clarification of an atypical or severe presentation [101]B2a. The investigations review evaluated viral testing and laboratory investigations in hospitalized infants and specifically included severe subgroups, but the supplied evidence does not provide sufficient study-level results to recommend a universal testing strategy or a particular assay [101]B2a. In community primary care, a retrospective Italian cohort of children aged 9–36 months evaluated whether implementation of RSV rapid antigen diagnostic testing was associated with antibiotic prescribing for viral lower-respiratory-tract infections [347]. This evidence addresses prescribing behavior rather than diagnostic accuracy or bronchiolitis outcomes; therefore, an RSV result should not by itself determine antibiotic treatment [347].
Routine blood tests are not justified solely by a typical bronchiolitis presentation. In PICU patients with RSV bronchiolitis, a retrospective cohort of 224 children developed and internally validated a prediction model for septic shock using routine blood biomarkers, clinical variables, and concomitant fungal infection [68]B2b. This type of model is relevant only to critically ill patients in whom sepsis or shock is clinically suspected; it should not be extrapolated to otherwise typical, stable bronchiolitis [68]B2b.
Differential diagnosis and special populations
Consider pneumonia, sepsis, asthma or recurrent viral-triggered wheeze, foreign-body aspiration, congenital airway or cardiac disease, and upper-airway obstruction when the course, examination, age, or response to supportive care is atypical. The diagnostic distinction between bronchiolitis and asthma is clinically consequential: a 2026 analysis of hospitalized children younger than 36 months found that combining asthma and bronchiolitis diagnoses was associated with increased cost and resource utilization, highlighting the importance of accurate diagnostic labeling and avoidance of unsupported dual diagnoses [343].
Children with Down syndrome have increased respiratory-illness hospitalization and intensive-care risk; a cohort of 2,327 children examined which co-occurring diagnoses were associated with respiratory-related admission and intensive care [341]. In such high-risk children, a lower threshold for observation, targeted investigations, and reassessment is reasonable, while testing should remain guided by the clinical question [341]. A regional Italian hub-and-spoke study of 562 hospitalized children aged 0–2 years incorporated clinical, microbiological, and treatment data to examine severity stratification and predictors of transfer to a tertiary hub, supporting structured assessment of severity and care location rather than diagnosis by testing alone [322]C.
| Clinical situation | Recommended approach | Evidence |
|---|---|---|
| Typical, stable bronchiolitis | Clinical assessment and serial reassessment; avoid routine imaging and blood tests | [101]B2a |
| Atypical presentation or deterioration | Targeted chest radiography, laboratory testing, or viral testing according to the suspected alternative diagnosis or complication | [101]B2a |
| Respiratory distress with diagnostic uncertainty | Consider LUS as an adjunct, especially when distinguishing bronchiolitis from recurrent infection-associated wheeze | [340][346] |
| Severe RSV bronchiolitis in PICU with concern for shock | Consider clinically indicated laboratory evaluation; prediction models remain internally validated and population-specific | [68]B2b |
| High-risk comorbidity, including Down syndrome | Intensify observation and reassessment; tailor investigations to clinical findings | [341] |
Severity Grading, Staging & Risk Stratification
- ▸Use serial clinical assessment rather than a single test; respiratory trajectory, work of breathing, oxygen requirement, feeding, hydration, alertness, apnea, and respiratory-support intensity are central to grading. [348][349][352]
- ▸Severe or critical bronchiolitis is operationally associated with HFNC, CPAP, BiPAP, invasive ventilation, marked distress, apnea, exhaustion, impaired gas exchange, or inability to maintain hydration. [348][352]
- ▸WBSS and the ROX index can support structured HFNC assessment, but the cited evidence does not provide universal bronchiolitis cut-offs. [348]
- ▸Lung ultrasound may help predict hospitalization, oxygen therapy, non-invasive ventilation, or ventilatory-support requirement, but it remains an adjunct to clinical assessment. [354][358][362]
- ▸Routine chest radiography does not improve ICU length of stay or respiratory-support outcomes in critical bronchiolitis and should not be used solely for severity staging. [357]
- ▸Admission wheezing may identify increased short-term severity and higher subsequent risk of preschool respiratory morbidity. [288][351]
- ▸Risk models, hub-and-spoke criteria, immune markers, and septic-shock prediction tools are context-specific or investigational and require local validation before routine use. [68][132][322][350]
Principles of severity assessment
Bronchiolitis severity should be graded dynamically rather than from a single diagnostic finding, because clinical deterioration, oxygen requirement, respiratory-support intensity, feeding tolerance, and response to treatment determine monitoring and disposition. Contemporary studies have used clinical categories ranging from mild to moderate and severe disease, but the available evidence does not establish one universally applicable staging system. [350] Severity assessment is particularly important in infants younger than 6 months and in children requiring non-invasive respiratory support, although the cited studies used different age ranges and clinical settings. [348][349]C[352]
At each assessment, document work of breathing, respiratory rate, apnea or exhaustion, oxygen saturation and oxygen requirement, hydration and feeding, mental status, and the trajectory over time. The need for supplemental oxygen or escalation from standard oxygen to HFNC, CPAP, BiPAP, or invasive ventilation represents an increasingly severe respiratory phenotype and should guide location of care. [352][353] In PICU cohorts, severe bronchiolitis was defined operationally by the requirement for non-invasive ventilatory support, including HFNC, CPAP, or BiPAP. [352]
Practical clinical stages
Mild disease generally describes infants with increased respiratory symptoms but preserved oxygenation, feeding, hydration, and alertness, without clinically significant respiratory distress or need for respiratory support. The cited prospective immunologic cohort classified patients as mild, moderate, or severe, but the abstract does not provide validated numerical thresholds for these categories. [350]
Moderate disease indicates more evident tachypnea or work of breathing, reduced feeding or hydration reserve, and/or a requirement for supplemental oxygen, while the infant remains clinically stable without imminent ventilatory failure. Wheezing at admission was associated with greater illness severity and greater oxygen exposure during hospitalization in a prospective cohort of previously healthy, full-term infants hospitalized with bronchiolitis. [351]
Severe or critical disease is characterized by marked respiratory distress, apnea, exhaustion, impaired gas exchange, inability to maintain hydration or feeding, or the need for HFNC or other non-invasive ventilatory support. [348][352] Infants with severe bronchiolitis requiring HFNC have been studied using structured serial assessment with the Wang Bronchiolitis Severity Score (WBSS) and the ROX index, calculated as SpO2/FiO2 divided by respiratory rate; the cited abstract does not provide validated universal cut-off values for either measure. [348] A standardized HFNC protocol has also incorporated criteria for initiation, flow titration, weaning, escalation, and PICU alerting when deterioration occurs, illustrating that respiratory-support decisions should be protocolized and continuously reassessed. [349]C
Risk stratification for escalation and disposition
Risk stratification should integrate current severity with age, prematurity or comorbidity, feeding and hydration, apnea risk, oxygen trajectory, and the availability of appropriate monitoring. In a multicenter PICU cohort of infants aged 3 days to 6 months, weaning strategy and weaning failure were evaluated after support with HFNC, CPAP, or BiPAP; HFNC used for de-escalation was examined as a distinct strategy, and weaning failure had implications for length of stay. [352] A nurse-driven HFNC weaning randomized trial in infants aged 1–24 months with severe bronchiolitis evaluated whether WBSS- and ROX-guided assessments could shorten HFNC duration and hospitalization. [348]
Regional systems may use severity stratification to allocate patients between spoke hospitals and tertiary hubs. In an Italian hub-and-spoke study of 562 hospitalized children aged 0–2 years, clinical, microbiological, demographic, and treatment variables were analyzed to identify predictors of centralization. [322]C Such models are healthcare-system specific and should not be treated as universally validated bedside scores. [322]C
External validation data from Kenya evaluated six pediatric acute lower respiratory infection mortality scores—RISC, mRISC, RISC-Malawi, PERCH, PREPARE, and ReSVinet—in 2,182 children aged 2–24 months hospitalized with severe disease. [132]B2b These scores may inform risk assessment in resource-limited settings, but their performance in routine bronchiolitis populations or high-resource settings cannot be assumed from this study alone. [132]B2b
Adjunctive and prognostic markers
Lung ultrasound is a potential adjunct when clinical assessment is uncertain. Prospective studies have examined regional pulmonary involvement and Brat scoring in infants with bronchiolitis, with associations between ultrasound abnormalities and the need for ventilatory support. [358] In an emergency-department cohort of infants younger than 12 months, point-of-care lung-ultrasound scores were evaluated for predicting hospitalization, oxygen therapy, and non-invasive ventilation. [362] A separate pediatric study assessed global lung-ultrasound scores in critically ill children with acute respiratory failure from different etiologies and severities, including lower respiratory tract infection and acute respiratory distress syndrome. [354] These findings support LUS as an adjunct, not a replacement for serial clinical assessment, and the cited studies do not establish a single bronchiolitis-specific threshold for ICU admission. [354][358][362]
Routine chest radiography should not be used as a severity substitute or performed solely to stage bronchiolitis. In children with critical bronchiolitis, a retrospective study found that obtaining chest radiographs did not improve ICU length of stay or level of respiratory support; the study used the Critical Bronchiolitis Score to calculate predicted outcomes. [357]
Long-term and contextual risk
Wheezing during the index admission may identify a clinically distinct subgroup: wheezing infants had more severe inpatient illness and were more likely to develop preschool wheezing or other respiratory morbidity during four years of follow-up. [351] Among children with severe hospitalized bronchiolitis, differing asthma definitions—including parent-reported physician diagnosis with or without bronchodilator response—altered estimates of subsequent asthma incidence, severity, control, and diagnostic performance. [288]
Post-infectious bronchiolitis obliterans is a rare but severe chronic obstructive condition following severe lower respiratory tract infection; in a French multicentre series, younger age and viral triggers were associated with the condition. [361] Respiratory syncytial virus epidemiology also changes over time: a German multicentre prospective study reported altered seasonality and increased respiratory failure among hospitalized RSV-positive children younger than 2 years after the emergence of SARS-CoV-2. [353]
Preventive interventions can change the observed severity distribution. Observational studies of nirsevimab evaluated its effects on bronchiolitis incidence, severity, viral etiology, and hospitalization, including clinical and lung-ultrasound presentations of hospitalized lower respiratory tract infections. [355][359] Immune profiling has additionally shown that CD4+ T-cell levels decreased with increasing bronchiolitis severity, while regulatory T-cell frequencies were higher in mild disease and lower in moderate and severe disease; these findings remain investigational and are not bedside grading tools. [350]
Finally, PICU-level risk should include complications beyond respiratory support. A prediction model for septic shock was developed in 224 children with RSV bronchiolitis admitted to PICU using routine clinical and laboratory variables and concomitant fungal infection. [68]B2b Resource utilization is also severity-sensitive: PICU financial analyses have examined diagnosis-specific charges and costs per PICU day across national databases, supporting the need for early, accurate triage without implying that cost is a clinical severity criterion. [356] Early return risk after discharge may be relevant to safety-netting; a tertiary-hospital study evaluated seven-day emergency-department returns after discharge for acute respiratory infection in relation to patient and encounter characteristics. [360]
| Stage | Typical clinical profile | Escalation implications |
|---|---|---|
| Mild | Respiratory symptoms without clinically significant distress, oxygen requirement, feeding compromise, dehydration, or altered alertness. [350] | Supportive care and reassessment according to local pathway. [349]C |
| Moderate | More evident tachypnea or work of breathing, reduced feeding or hydration reserve, and/or supplemental oxygen requirement without imminent ventilatory failure. [350][351] | Close serial review; assess trajectory and oxygen needs. [349]C |
| Severe/critical | Marked distress, apnea, exhaustion, impaired gas exchange, feeding or hydration failure, or need for HFNC, CPAP, or BiPAP. [348][352] | Consider higher-acuity monitoring, escalation protocols, and PICU consultation. [349]C[352] |
| Domain | Evidence-supported use |
|---|---|
| Respiratory support | HFNC, CPAP, or BiPAP requirement identifies severe PICU bronchiolitis; weaning failure may prolong stay. [352] |
| Structured scores | WBSS and ROX have been incorporated into HFNC initiation and weaning protocols; universal thresholds are not established in the cited abstracts. [348][349]C |
| Lung ultrasound | Brat or global LUS scores may correlate with ventilatory support or acute respiratory-failure severity. [354][358][362] |
| Complication risk | RSV PICU patients may be stratified for septic shock using clinical and laboratory variables. [68]B2b |
| Longer-term risk | Wheezing at admission, severe infection, and younger age or viral triggers may identify risk for later respiratory disease or PIBO. [288][351][361] |
Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization
- ▸Use supportive care with repeated assessment of airway, work of breathing, oxygenation, hydration, feeding, and mental status [146].
- ▸No supplied reference provides a delivery-room neonatal resuscitation protocol; use the applicable neonatal resuscitation standard for birth-related compromise.
- ▸Consider oxygen and monitored HFNC for clinically significant hypoxaemia or persistent moderate-to-severe distress; establish escalation criteria before starting support [156,158,367].
- ▸Evidence supplied here does not establish a preferred SpO₂ target between **88% and 92%** because the OxyKids results are not provided [364].
- ▸Do not routinely use nebulized adrenaline, corticosteroids, salbutamol, palivizumab treatment, or other adjunctive therapies for typical bronchiolitis [144,155,157].
- ▸Escalate promptly when respiratory effort, gas exchange, consciousness, perfusion, or feeding deteriorates despite supportive measures [158].
Scope and immediate priorities
Bronchiolitis is managed primarily with supportive care; international guidelines recommend supportive treatment, although non-evidence-based therapies remain common in practice [146]A1b. This section applies to infants and children with suspected acute bronchiolitis and does not replace a neonatal resuscitation algorithm for birth-related apnea, bradycardia, or circulatory collapse; none of the supplied references evaluates neonatal positive-pressure ventilation, chest compressions, umbilical access, or medication dosing during delivery-room resuscitation. Assess airway patency, work of breathing, respiratory rate, oxygenation, feeding and hydration, mental status, and response to initial support, with repeated reassessment because escalation decisions in trials were based on clinical deterioration and treatment failure [158]A1b.
Clear nasal secretions when they interfere with breathing or feeding, but avoid routine aggressive suctioning. In a randomized trial of otherwise healthy infants aged 1–11 months discharged from the emergency department, enhanced battery-operated suctioning before feeds was compared with minimal bulb suctioning for 72 hours; the study was specifically designed to determine whether enhanced suctioning improved outcomes [159]A1b. The abstract supplied does not report the numerical outcome, so enhanced suctioning should not be presented as superior on the basis of this reference [159]A1b.
Oxygen and respiratory support
Provide supplemental oxygen for clinically important hypoxaemia and titrate to the locally adopted target. The supplied evidence includes a multicentre randomized trial comparing oxygen-treatment thresholds of 88% versus 92% SpO₂ in children aged 6 weeks–12 years with bronchiolitis, lower respiratory tract infection, or viral-induced wheeze; oxygen could be delivered by low-flow or high-flow nasal cannula or face mask [364]. Because the supplied abstract does not provide the trial’s safety and length-of-stay results, it cannot establish that either threshold is preferable [364]. Avoid treating an isolated saturation value without considering respiratory effort, perfusion, feeding, and clinical trajectory [364].
HFNC is an option for infants with persistent hypoxaemia or moderate-to-severe respiratory distress despite basic supportive measures, provided that monitoring and an escalation pathway are available [156]B2b[158]A1b[367][370]. A ward-based HFNC guideline was evaluated in a retrospective pre–post interrupted-time-series study of 1,937 infants with bronchiolitis; outcomes included hospital length of stay, PICU transfer, PICU length of stay, intubation, and 30-day readmission [156]B2b. The supplied abstract does not provide the numerical results, so ward HFNC should not be assumed to reduce these outcomes [156]B2b.
Randomized studies compared HFNC with bubble CPAP or CPAP in moderate-to-severe bronchiolitis. The 2024 trial enrolled children aged 1–23 months and defined treatment failure within 24 hours using clinical deterioration criteria including a ≥1-point increase in modified Wood’s Clinical Asthma Score or a respiratory-rate increase of >10 breaths/min; the remaining supplied abstract is truncated before the results [158]A1b. A separate randomized trial of 50 children compared CPAP with HFNC and assessed respiratory rate, carbon dioxide tension, clinical score, treatment failure, treatment duration, pain score, and hospitalization length; the abstract reports no differences in the evaluated outcomes [370]. These studies support selecting noninvasive support according to severity, monitoring capacity, and local expertise rather than treating HFNC as universally equivalent or superior to CPAP [158]A1b[370].
Flow-rate evidence is limited. A study comparing 1 versus 2 L/kg/min heated humidified HFNC in severe bronchiolitis evaluated treatment failure, respiratory and heart rates, clinical score, SpO₂, weaning, intubation, and ICU admission [371]. Another randomized trial compared HFNC at 2 L/kg/min with low-flow oxygen in children aged 1–24 months requiring oxygen and assessed normalization of heart rate, respiratory rate, clinical score, treatment failure, length of stay, oxygen duration, and adverse events [367]. The supplied abstracts do not provide complete numerical results; therefore, flow should be prescribed and adjusted using the device specification, patient size, clinical response, and institutional protocol [367][371].
Prone positioning has been evaluated in infants aged ≤6 months with moderate-to-severe bronchiolitis receiving HFNC in a 2026 multicentre randomized trial. The primary question was whether prone positioning reduced escalation to noninvasive or invasive ventilation; the supplied abstract does not report the result [339]. It should therefore not be described as proven to prevent ventilatory escalation [339].
Therapies not routinely indicated
Nebulized adrenaline and inhaled or oral glucocorticoids did not reduce hospitalization or relieve symptoms in infants with bronchiolitis and should not be used routinely [157]A1c. In an intensive-care randomized trial, systemic corticosteroids plus repeated nebulized epinephrine were compared with standard care for children younger than 18 months receiving positive-pressure support; the intervention used a six-day prednisolone regimen and scheduled nebulized epinephrine, with duration of positive-pressure support as the primary outcome [86]A1b. The supplied abstract does not report the outcome, so intensive-care admission alone is not a sufficient reason to use this combination [86]A1b.
Salbutamol is not effective for bronchitis-related cough; bronchodilator benefit described in the Finnish guidance applies to wheezing bronchitis, not routine infant bronchiolitis [155]A1c[157]A1c. Palivizumab is prophylaxis for selected high-risk infants during RSV seasons, not established treatment for acute RSV bronchiolitis; a randomized trial in RSV-positive infants aged ≤3 months assessed intravenous palivizumab versus placebo for readmission, discharge readiness, PICU requirement, and revisits [144]A1b. Zinc, vitamin D, hypertonic saline, music or noise isolation, respiratory physiotherapy, and automatic oxygen titration were investigated in individual studies, but the supplied abstracts do not establish a routine emergency standard for these interventions [365][366][369]C[372].
Exclusions and diagnostic caution
The ATS guideline on bronchiolitis obliterans syndrome addresses surveillance and evaluation after pediatric hematopoietic stem-cell transplantation, not acute viral bronchiolitis stabilization [8]A1c. A pediatric lung-transplant trial of rituximab addressed donor-specific antibodies and transplant outcomes, not emergency bronchiolitis treatment [368]. Digital parental education tools were evaluated for knowledge of several childhood conditions, including bronchiolitis, but do not provide physiologic stabilization guidance [95]A1b.
| Intervention | Evidence and practical interpretation |
|---|---|
| Nasal clearance | Enhanced versus minimal suctioning was tested in discharged infants; superiority is not established in the supplied abstract [159]A1b. |
| Oxygen | Randomized threshold comparison: 88% versus 92% SpO₂; numerical outcomes are not supplied [364]. |
| HFNC | Studied in ward, emergency, and inpatient settings; use with monitoring and a clear escalation pathway [156]B2b[367]. |
| CPAP/bubble CPAP | Randomized comparisons with HFNC assessed treatment failure and physiologic outcomes; one trial reported no differences, while another abstract is incomplete [158]A1b[370]. |
| Prone positioning | Randomized in HFNC-supported infants; outcome data are not supplied [339]. |
| Corticosteroid plus epinephrine | Intensive-care randomized regimen studied, but supplied abstract does not report benefit; not routine therapy [86]A1b. |
Long-term & Definitive Management
- ▸Use supportive care as the definitive approach for uncomplicated bronchiolitis; routine bronchodilators, glucocorticoids, antibiotics, epinephrine, and chest radiography are low-value or unsupported interventions.[164][10]
- ▸Do not use azithromycin routinely: pooled trials showed no ICU-treatment benefit, with a risk difference of 0.0% and low-certainty evidence.[373]
- ▸Use HFNC or NIV according to respiratory severity and local escalation protocols; evidence does not establish one universal respiratory-support strategy.[375][158]
- ▸A single dose of nirsevimab reduced RSV lower-respiratory-tract infections by 63% in a large meta-analysis, but it prevents RSV disease rather than treating established bronchiolitis.[250]
- ▸RSV prophylaxis has not been proven to prevent later recurrent wheeze or asthma.[379]
- ▸Apply dedicated BOS surveillance after pediatric allogeneic HSCT; this is a distinct high-risk pathway.[8]
Scope and treatment principles
Bronchiolitis is generally managed with supportive care rather than a disease-modifying drug; the supplied evidence evaluates acute-care interventions, prevention of RSV disease, and surveillance for selected chronic complications rather than a curative long-term therapy.[164]A1a Management should therefore focus on adequate hydration and nutrition, oxygenation, respiratory-support escalation when required, avoidance of ineffective or low-value medicines, and follow-up tailored to risk.[164]A1a[375]
Medicines and procedures not recommended routinely
Evidence syntheses and national guidance do not support routine bronchodilator, systemic glucocorticoid, antibiotic, epinephrine, or other pharmacological treatment for uncomplicated bronchiolitis.[164]A1a[10]B2b The updated Finnish guideline found strong evidence that beta-sympathomimetics were ineffective for bronchitis-related cough; this supports avoiding beta-sympathomimetics when bronchiolitis is being treated as an uncomplicated viral lower-respiratory illness.[155]A1c A 2-year follow-up of a cluster-randomized de-implementation trial showed that an intervention improving avoidance of chest radiography, salbutamol, glucocorticoids, antibiotics, and epinephrine was associated with 85.1% compliance during the intervention year, with a reported adjusted improvement of 14.1 percentage points compared with control hospitals; sustained practice effects were the subject of the follow-up study.[10]B2b
Azithromycin should not be used routinely for acute bronchiolitis or wheezing in children younger than 2 years. In a systematic review of seven randomized trials, the risk difference for intensive-care treatment was 0.0% (95% CI, −2.0% to 2.0%; low-certainty evidence), providing no demonstrated ICU benefit.[373] Antibiotics should be reserved for a separate, clinically supported bacterial infection rather than viral bronchiolitis; evidence from low-resource settings addressed selected children with WHO-defined fast-breathing pneumonia and should not be automatically extrapolated to bronchiolitis.[376]
Chest physiotherapy is not routinely recommended for hospitalized children with bronchiolitis. The supplied randomized-trial report notes that updated evidence found, at most, a small improvement in clinical severity with prolonged slow-expiration techniques, with low certainty and uncertain clinical importance; the trial examined whether this technique altered 24-hour food intake.[181]A1b Inhaled nitric oxide has been studied in infants requiring emergency assessment or hospitalization, with ICU admission, hospital stay, and adverse events as outcomes, but the supplied abstract does not report a clinical benefit that would justify routine use.[374] Ribavirin has likewise been evaluated in a systematic review of aerosolized or oral therapy for RSV lower-respiratory-tract infection, including randomized and observational studies; the supplied evidence does not establish routine use for typical bronchiolitis.[377]
Oxygen and respiratory support
For infants who require noninvasive respiratory support, high-flow nasal cannula (HFNC), conventional low-flow oxygen, and noninvasive ventilation (NIV) have been compared in systematic reviews including thousands of children younger than 24 months.[375] HFNC is a respiratory-support option when conventional oxygen is inadequate, but the network meta-analysis included both randomized and nonrandomized evidence and therefore does not establish one universally superior modality.[375] A randomized trial comparing HFNC with nasal-prong bubble CPAP in children aged 1–23 months with moderate-to-severe bronchiolitis used treatment failure within 24 hours as its primary outcome; the supplied abstract does not provide the comparative result.[158]A1b Similarly, a randomized trial comparing 1, 2, and 3 L/kg/min HFNC flow rates in infants was designed to identify an optimal setting, but the supplied evidence does not report the outcome.[179]A1b
HFNC should be monitored and weaned according to clinical response and local protocol. A nurse-driven randomized trial evaluated structured weaning using the Wang Bronchiolitis Severity Score and ROX index, with HFNC duration and hospitalization as outcomes; the supplied abstract does not report whether the protocol reduced either outcome.[348] Prone positioning in infants aged 6 months or younger receiving HFNC was evaluated in a multicentre randomized trial for its effect on escalation to NIV or invasive ventilation, but no result is provided in the supplied evidence.[339] Oxygen-saturation targets should follow the responsible service’s protocol while evidence evolves: the OxyKids trial was designed to compare 88% versus 92% thresholds in children with respiratory distress, including bronchiolitis, but the supplied abstract does not report safety or length-of-stay results.[364]
Prevention and longer-term follow-up
A single dose of nirsevimab was associated with a 63% reduction in RSV lower-respiratory-tract infections in a 2025 meta-analysis pooling 425,362 infants from 26 studies, including six randomized trials and 20 observational cohorts.[250]A1a Eligibility, timing, and seasonal implementation should follow current local immunization policy; nirsevimab prevents RSV disease and is not treatment for established bronchiolitis.[250]A1a
RSV monoclonal-antibody prophylaxis has reduced RSV-related hospitalization in high-risk infants, but evidence remains conflicting regarding prevention of subsequent recurrent wheeze or asthma; a systematic review therefore does not establish prophylaxis as a strategy for preventing those long-term outcomes.[379] Children with persistent or recurrent respiratory symptoms after severe bronchiolitis should be assessed clinically, but the supplied references do not define a universal bronchiolitis follow-up schedule.[379]
Children after allogeneic hematopoietic stem-cell transplantation require separate surveillance for bronchiolitis obliterans syndrome (BOS), the most common noninfectious pulmonary complication after pediatric HSCT. The 2024 American Thoracic Society guideline was developed to standardize surveillance and evaluation because international recommendations had conflicted.[8]A1c This pathway applies to post-HSCT BOS risk, not routine bronchiolitis in otherwise healthy children.[8]A1c
| Intervention | Long-term/definitive role | Evidence |
|---|---|---|
| Supportive care | Main approach for uncomplicated bronchiolitis | [164]A1a[375] |
| Salbutamol/beta-sympathomimetics, glucocorticoids, epinephrine, routine antibiotics | Avoid routinely | [10]B2b[155]A1c[164]A1a |
| Azithromycin | Not routine; no demonstrated ICU benefit | [373] |
| Chest physiotherapy | Not routinely recommended; clinical benefit uncertain | [181]A1b |
| HFNC/NIV | Escalation support for respiratory compromise; select and wean by clinical response | [375][158]A1b[348] |
| Nirsevimab | RSV prevention in eligible infants; not treatment | [250]A1a |
| Post-HSCT BOS surveillance | Dedicated follow-up pathway for high-risk children | [8]A1c |
History and Evolution of Treatment
- ▸Modern acute bronchiolitis management emphasizes supportive care, judicious oxygen, and escalation according to respiratory severity rather than routine medication. [347]
- ▸Oxygen strategies are being reassessed around thresholds of **88% versus 92%**, while HFNC practice is being standardized and its flow and weaning protocols studied. [364] [179] [348] [349]
- ▸Prone positioning, NAVA optimization, analgesia selection, and surfactant are newer approaches being evaluated for severe or life-threatening bronchiolitis. [339] [225] [380] [178]
- ▸RSV prevention has expanded to universal infant nirsevimab programs and maternal vaccination, although maternal vaccine safety requires continued monitoring. [383] [224]
- ▸BOS after hematopoietic-cell or lung transplantation requires separate surveillance and treatment pathways, including serial PFTs, HRCT, infection evaluation, and investigation of antifibrotic and biomarker-based strategies. [210] [218] [381] [384]
From disease-directed therapy to supportive care
Treatment of acute infant bronchiolitis has progressively moved away from routine disease-directed medication and toward severity-based supportive care. This approach reflects the predominantly viral nature of bronchiolitis and the continuing problem of inappropriate antibiotic use in viral lower respiratory tract infections; a 2026 community study specifically evaluated whether rapid RSV antigen testing could influence antibiotic-prescribing decisions in children aged 9–36 months. [347] Educational interventions have also evolved: a Canadian randomized trial tested weekly image-based “blogshots” to improve parental understanding of evidence-based recommendations for bronchiolitis and other common childhood illnesses. [95]A1b
RSV remains the principal target of prevention because it is a leading cause of hospitalization for infant lower respiratory tract infection and severe disease is associated with later recurrent wheeze and asthma risk. [216]A1c Prevention has therefore expanded from counseling and infection-control measures to passive immunization. A population-based study in Galicia evaluated universal infant nirsevimab prophylaxis across two RSV seasons, measuring RSV-related lower respiratory tract infection hospitalization and outpatient outcomes. [383] Maternal vaccination is another preventive strategy, but its development requires careful safety surveillance: a phase 3 trial of RSVPreF3-Mat in high-risk pregnant women was stopped and unblinded after an increased risk of preterm birth had been observed with the vaccine in another trial of healthy pregnant women. [224]A1b
Oxygen therapy and escalation of respiratory support
Oxygen supplementation remains supportive rather than antiviral treatment. The historical tendency to use relatively conservative oxygen thresholds has increasingly been challenged because unnecessary oxygen can prolong hospitalization. The multicentre OxyKids randomized trial compared an SpO2 threshold of 88% with 92% in children aged 6 weeks–12 years requiring oxygen for bronchiolitis, lower respiratory tract infection, or viral-induced wheeze; oxygen could be delivered by low-flow or high-flow nasal cannula or face mask. [364] The trial was designed to determine whether the lower threshold could safely reduce hospital stay, illustrating the modern shift toward avoiding overtreatment while preserving safety. [364]
High-flow nasal cannula (HFNC) has become an important intermediate step for moderate-to-severe bronchiolitis, particularly when conventional oxygen is inadequate. However, optimal flow remains unsettled. A randomized trial in infants aged 1 month–1 year compared 1, 2, and 3 L/kg/min of humidified HFNC. [179]A1b Implementation has also become more protocolized: an Italian quality-improvement project standardized HFNC initiation, flow titration, escalation criteria, and PICU alerts for children younger than 24 months treated in the emergency department and hospital during three winter seasons. [349]C A separate randomized trial evaluated a nurse-driven weaning protocol using structured bronchiolitis severity assessment and the ROX index, with the aim of reducing HFNC duration and hospitalization in infants aged 1–24 months with severe disease. [348]
Positioning is a newer nonpharmacological adjunct. The PROPOSITIS multicentre randomized trial investigated whether prone positioning in infants aged 6 months or younger with moderate-to-severe bronchiolitis receiving HFNC reduced escalation to noninvasive or invasive ventilation. [339] This reflects increasing interest in improving respiratory mechanics without immediately increasing ventilatory intensity.
Critical illness and mechanical ventilation
For life-threatening bronchiolitis, invasive ventilation remains a rescue therapy, but treatment has become more physiologically individualized. A randomized crossover feasibility study examined low-dose versus standard-dose morphine in infants receiving neurally adjusted ventilatory assist (NAVA), assessing neural respiratory drive, diaphragm electrical activity, estimated occlusion pressure, comfort, and physiological tolerance. [225]A1b A mechanistic study in invasively ventilated infants evaluated combinations of PEEP, pressure support, and NAVA support, including PEEP levels of 1, 5, and 10 cm H2O, to examine respiratory drive, efficiency, synchrony, and expiratory flow limitation. [380]
Exogenous surfactant represents an investigational attempt to treat the severe pathophysiology of critical bronchiolitis rather than only its consequences. The BESS phase 2 trial used a multicentre, blinded, randomized, sham-controlled design to assess endotracheal poractant alfa in infants with life-threatening bronchiolitis after earlier small studies suggested possible improvement in gas exchange. [178]A1b Its phase 2 status indicates that surfactant had not yet become established routine therapy on the evidence supplied here. [178]A1b
Bronchiolitis obliterans and post-transplant pulmonary disease
The term bronchiolitis also encompasses bronchiolitis obliterans syndrome (BOS), a distinct fibrotic small-airway disorder after transplantation. After allogeneic hematopoietic stem-cell transplantation, pulmonary chronic graft-versus-host disease—particularly BOS—is associated with substantial morbidity and mortality. Taiwan consensus guidance emphasizes early detection with serial pulmonary function tests, while HRCT is a valuable diagnostic tool and bronchoalveolar lavage with multiplex PCR assists evaluation for infection and alternative diagnoses. [210]A1c Newer transplant literature recognizes that lung complications after hematopoietic-cell transplantation are heterogeneous: restrictive phenotypes such as HCT-associated organizing pneumonia and truncal sclerosis should not automatically be grouped with BOS because their timing and prognostic profiles may differ. [384]
After bilateral lung transplantation, BOS is characterized by progressive FEV1 loss from fibrotic small-airway scarring. Pirfenidone, an antifibrotic used for idiopathic pulmonary fibrosis, was tested against placebo in a European multicentre randomized phase 2 trial for progressive BOS despite standard care. [218]A1b Biomarker-based monitoring is also being explored: plasma desmosine, a product of elastin breakdown, was evaluated in patients with chronic graft-versus-host disease as a candidate marker of pulmonary and cutaneous fibrotic involvement, including NIH-defined BOS. [381]
Finally, research increasingly links acute bronchiolitis to longer-term outcomes and biological mechanisms. A four-year prospective cohort found physician-diagnosed persistent asthma in 26.3% of children after bronchiolitis and examined associations with IFN-λ3 polymorphisms and parental asthma history. [382] Immune-checkpoint and cytokine abnormalities, including changes in regulatory T-cell populations, were associated with bronchiolitis severity in a prospective pediatric cohort. [350] Environmental exposures, including meteorological conditions, ozone, and maternal or individual-level factors, have also been investigated as contributors to childhood bronchiolitis. [54]B2b
| Treatment domain | Earlier or conventional emphasis | Newer evidence-informed direction |
|---|---|---|
| Oxygen | Oxygen for hypoxemia, often using higher thresholds | Randomized comparison of 88% vs 92% SpO2 thresholds to reduce potential overtreatment. [364] |
| HFNC | Increasing use without uniform practice | Comparison of 1, 2, and 3 L/kg/min, standardized initiation and escalation, and nurse-driven weaning protocols. [179]A1b [348] [349]C |
| Severe disease | Escalation to noninvasive or invasive ventilation | Prone positioning, NAVA/PEEP optimization, and evaluation of poractant alfa. [339] [178]A1b [380] |
| Prevention | Infection prevention and counseling | Universal infant nirsevimab and maternal RSV vaccine programs, balanced against safety surveillance. [383] [224]A1b |
| Post-transplant bronchiolitis | Recognition and treatment of BOS | Serial PFT surveillance, HRCT, phenotype-specific assessment, pirfenidone trials, and biomarker research. [210]A1c [218]A1b [381] [384] |
Growth, Development & Nutrition Impact
- ▸Bronchiolitis can impair oral intake; respiratory support may delay feeding initiation, so hydration and nutrition require active reassessment. [178][392]
- ▸The pediatric critical-care protein evidence evaluates thresholds of <1.1 g/kg/day and >2 g/kg/day, but it does not establish bronchiolitis-specific targets. [241]
- ▸Post-discharge follow-up should include feeding recovery, hydration, weight trajectory, and respiratory symptoms. [351][392]
- ▸Admission wheezing is associated with greater acute severity and later preschool respiratory morbidity in the supplied cohort. [351]
- ▸Molecular and immune findings in severe bronchiolitis are biologically informative but do not prove effects on growth or development. [350][385]
- ▸Unnecessary early PPI exposure should be avoided because potential respiratory infection risk must be weighed against limited benefit for common functional gastrointestinal symptoms. [242]
Acute nutritional and feeding impact
Bronchiolitis commonly causes coryza and feeding difficulty; in severe disease, respiratory distress, tachypnea, fatigue, and the need for respiratory support can compromise oral intake and increase the risk of inadequate hydration and energy delivery. [178]A1b Infants receiving non-invasive respiratory support through nasal interfaces may experience delayed initiation of enteral feeds because of safety concerns. [392] In a retrospective cohort of children aged 0–24 months with bronchiolitis treated with non-invasive respiratory support, feeding by mouth and orogastric tube was evaluated in relation to clinically significant adverse events; the available abstract does not provide the study’s numerical outcome estimates, so it should not be interpreted as establishing universal feeding safety criteria. [392]
When oral intake is insufficient, enteral nutrition is the preferred route when clinically feasible, with the feeding method and rate individualized to respiratory status, airway protection, gastrointestinal tolerance, and aspiration risk. This approach is consistent with the clinical question addressed by the feeding cohort, which specifically examined oral and orogastric feeding during non-invasive support. [392] Bronchiolitis requiring prolonged intensive care may also create cumulative nutritional risk through increased work of breathing, interrupted feeding, inflammation, sedation, mechanical ventilation, and prolonged hospitalization; however, the supplied bronchiolitis feeding study does not quantify changes in weight, length, or body-composition trajectories. [392]
Protein and critical illness
For children hospitalized in a pediatric intensive care unit for ≥48 hours and receiving enteral nutrition, protein delivery is a clinically important component of nutrition support. A 2025 systematic review and meta-analysis compared enteral protein intakes of <1.1 g/kg/day or >2 g/kg/day with internationally recommended intakes and considered energy intake when evaluating clinical and nutritional outcomes. [241]A1a This evidence concerns critically ill children broadly rather than infants with uncomplicated bronchiolitis; therefore, protein targets should not be extrapolated automatically to every infant with bronchiolitis. [241]A1a
In severe bronchiolitis, nutrition assessment should include pre-illness growth, recent weight change, hydration, usual feeding pattern, current enteral or parenteral intake, and the anticipated duration of respiratory support. The supplied evidence does not establish a bronchiolitis-specific protein dose, caloric prescription, or growth-monitoring interval. [241]A1a[392]
Growth and developmental considerations
Most infants with bronchiolitis recover without documented long-term growth or developmental impairment in the evidence supplied for this update; nonetheless, severe illness can interrupt feeding and normal caregiving routines during a sensitive developmental period. [178]A1b[392] Follow-up should therefore reassess return to usual feeding, weight trajectory, hydration, sleep, activity, and caregiver concerns after discharge, particularly after intensive care, prolonged respiratory support, or substantial feeding interruption. The cited studies do not provide validated bronchiolitis-specific developmental screening thresholds. [178]A1b[392]
Bronchiolitis severity is clinically heterogeneous. In a prospective cohort of infants and toddlers, increasing severity was associated with changes in circulating immune-cell and immune-checkpoint profiles, including reduced CD4-positive T-cell levels and differing regulatory T-cell frequencies across severity groups; these findings describe biological severity associations and do not demonstrate a direct effect on growth or neurodevelopment. [350] Severe bronchiolitis has also been linked to distinct relationships between nasopharyngeal microbiota and blood DNA methylation in a multicenter cohort of 504 infants younger than 1 year; these molecular associations do not establish nutritional causation or a developmental outcome. [385]
Longer-term respiratory health
The principal longer-term developmental concern after severe bronchiolitis is often respiratory rather than somatic growth. In a prospective cohort of 668 previously healthy, full-term infants hospitalized with bronchiolitis and followed for 4 years, wheezing at admission was associated with greater acute severity, including greater oxygen requirement, and increased likelihood of preschool wheezing or asthma-related outcomes after discharge. [351] A separate cohort of 2,628 children hospitalized for acute respiratory infections found that early-life human rhinovirus and respiratory syncytial virus infections were examined in relation to subsequent asthma, with timing during early developmental windows treated as an important exposure dimension; the supplied abstract does not provide the final effect estimates. [243]B3b
These associations should not be presented as proof that bronchiolitis, respiratory syncytial virus, or rhinovirus alone causes asthma, because host susceptibility, atopy, viral phenotype, environmental exposure, and illness severity may contribute. [243]B3b[351] Persistent or recurrent wheeze, exercise limitation, sleep disturbance, or repeated respiratory exacerbations warrants primary-care or respiratory follow-up rather than assuming that feeding or growth problems are the only sequelae. [351]
Medication and prevention considerations
Early proton-pump-inhibitor exposure is not a nutritional treatment for bronchiolitis or uncomplicated infant reflux. In a birth cohort followed to 24 months, exposure during the first 6 months and exposure during the first 24 months were evaluated for associations with respiratory tract infections; the supplied abstract reports that the study investigated this relationship but does not provide complete effect estimates. [242]B2b PPI prescribing should therefore be based on a clear indication, with potential infection risks considered alongside uncertain benefit for common functional gastrointestinal symptoms. [242]B2b
Prevention may reduce the burden of severe respiratory illness and its associated feeding disruption. An Italian primary-care study evaluated changes in bronchiolitis burden and age-related healthcare contacts after broad nirsevimab introduction in November 2024; the supplied abstract does not provide the final quantitative results. [324] Prevention strategies should be interpreted as reducing illness risk, not as a substitute for post-illness growth and feeding surveillance. [324]
Practical takeaways
- Assess feeding and hydration at every severity level, escalating from supported oral feeding to enteral feeding when intake is inadequate and respiratory status permits. [178]A1b[392]
- In PICU patients, document energy and protein delivery; interpret the <1.1 g/kg/day and >2 g/kg/day thresholds within the critically ill pediatric evidence base rather than applying them indiscriminately to bronchiolitis. [241]A1a
- Recheck weight trajectory and feeding recovery after severe disease or prolonged respiratory support. [178]A1b[392]
- Monitor for recurrent wheeze and asthma-related symptoms during follow-up, especially when wheezing was present at admission. [351]
- Avoid unnecessary PPI exposure and consider preventive RSV strategies where locally recommended. [242]B2b[324]
| Clinical context | Priority | Evidence |
|---|---|---|
| Feeding difficulty or respiratory distress | Assess intake, hydration, work of breathing, and ability to protect the airway. | [178]A1b[392] |
| Non-invasive respiratory support | Consider individualized oral or orogastric feeding; the available study does not provide universal safety thresholds. | [392] |
| PICU stay ≥48 hours | Track energy and protein delivery and interpret protein thresholds in the broader critically ill-child evidence base. | [241]A1a |
| After severe illness | Reassess weight trajectory, feeding recovery, recurrent wheeze, sleep, and activity. | [351][392] |
Complications
- ▸Severe bronchiolitis may progress to hypoxaemia, respiratory distress, feeding compromise, hospitalization, PICU admission, and HFNC requirement, with prematurity, congenital heart disease, chronic lung disease, and Down syndrome important risk contexts [396].
- ▸Single-dose nirsevimab reduced RSV-LRTIs by 63% across 26 studies involving 425,362 infants [250].
- ▸Later asthma and respiratory morbidity are recognized concerns after severe early-life viral LRTI, while post-transplant bronchiolitis obliterans is a distinct chronic small-airway complication [243][315][385][393].
- ▸Maternal RSVPreF3-Mat vaccine evaluation was stopped after a preterm-birth safety signal observed in another trial, requiring careful risk–benefit interpretation [224].
Acute respiratory complications
Bronchiolitis is usually self-limited, but severe disease can cause hypoxaemia, respiratory distress, feeding difficulty, dehydration, prolonged hospitalization, intensive-care admission, and the need for respiratory support. These complications are most clinically important in young infants and in children with prematurity, congenital heart disease, chronic lung disease of prematurity, or Down syndrome. In hospitalized children aged 12–23 months with RSV, these factors were specifically evaluated in relation to prolonged hospitalization, defined as more than 3 days, and pediatric intensive-care-unit admission [396]. Children with Down syndrome also have increased respiratory-illness hospitalization and intensive-care risk, although the contribution of specific coexisting diagnoses varies across childhood [341].
Respiratory failure may require high-flow nasal cannula (HFNC). A randomized trial in infants aged 1–24 months with severe bronchiolitis evaluated a nurse-driven weaning protocol using structured Wang Bronchiolitis Severity Score assessments and the ROX index, calculated from oxygen saturation, inspired oxygen fraction, and respiratory rate; outcomes included HFNC duration, time to first wean, and hospitalization duration [348]. Another randomized trial in infants aged 1 month–1 year with moderate-to-severe bronchiolitis compared HFNC flow rates of 1, 2, and 3 L/kg/min, reflecting ongoing uncertainty about the optimal flow rate and the potential for management-related complications such as unnecessarily prolonged support [179]A1b.
RSV is a major cause of bronchiolitis and lower respiratory tract infection (LRTI) hospitalization in infants. A 2025 meta-analysis including 425,362 infants from 26 studies found that single-dose nirsevimab reduced RSV-LRTIs by 63%, supporting prevention of severe RSV-related respiratory complications [250]A1a. Population-based surveillance in Galicia evaluated whether universal nirsevimab prophylaxis affected RSV-LRTI hospitalization and other hospital and primary-care outcomes across the first and second RSV seasons, although the supplied evidence does not provide the study’s numerical outcome estimates [383]. Similarly, an Italian multicenter observational study assessed regional implementation of nirsevimab during the 2023–2025 seasons and its clinical effect on RSV-related hospitalization and PICU admission [394]. A Spanish prospective study compared hospitalized LRTI presentations before and after universal nirsevimab implementation and included clinical, microbiological, and lung-ultrasound findings [359].
Diagnostic and treatment-related complications
Lung ultrasound is being evaluated as an alternative or complement to chest radiography in pediatric LRTI. In a prospective study of 338 children aged 1 month–18 years, both modalities were performed at admission and follow-up and compared using sensitivity, specificity, predictive values, accuracy, and agreement statistics; the evidence supports attention to diagnostic variability when interpreting imaging in children with bronchiolitis-like LRTI presentations [340].
Bronchiolitis may coexist with or be confused with other severe pulmonary infections. Severe Mycoplasma pneumoniae pneumonia can produce long-term pulmonary lesions; a randomized trial of 424 children compared azithromycin plus low-dose methylprednisolone (2 mg/kg/day) with azithromycin plus high-dose methylprednisolone (10 mg/kg/day) for 3 days, but these findings apply to severe M. pneumoniae pneumonia rather than routine viral bronchiolitis [249]A1b.
Preventive interventions also have safety considerations. A phase 3 trial of maternal RSVPreF3-Mat vaccination in high-risk pregnant women and their infants was stopped and unblinded after an increased preterm-birth risk associated with the vaccine was observed in another trial of healthy pregnant women; therefore, maternal vaccination safety and gestational-age eligibility require careful interpretation [224]A1b.
Chronic respiratory sequelae
Severe bronchiolitis has been associated with later respiratory morbidity, including asthma. A multi-center cohort of 504 infants hospitalized with severe bronchiolitis investigated relationships between nasopharyngeal microbiome profiles and blood DNA methylation, reflecting possible microbial, host-response, and epigenetic pathways underlying later disease [385]. A national cohort study of 2,628 children hospitalized with acute respiratory infection examined whether early-life human rhinovirus or RSV infection was associated with subsequent asthma, with particular attention to infection timing during developmental windows [243]B3b. A separate nationwide study evaluated asthma-related healthcare utilization after hospitalization for PCR-confirmed RSV-LRTI compared with LRTI caused by other respiratory viruses, including acute utilization outcomes [315].
Very preterm infants have additional long-term respiratory vulnerability, particularly bronchopulmonary dysplasia (BPD). A prospective cohort of infants born at less than 32 weeks’ gestation examined respiratory morbidity through 18 months and compared outcomes according to exposure to mother’s own milk versus pasteurized donor human milk [313]. These outcomes should be distinguished from bronchiolitis obliterans, a chronic obstructive small-airway disease that may follow infection, hematopoietic-cell transplantation, or lung transplantation [393]. After allogeneic hematopoietic-cell transplantation, bronchiolitis obliterans syndrome and idiopathic pneumonia syndrome are important causes of morbidity and mortality; in a cohort of 633 children and young adults, adenovirus reactivation and particular conditioning regimens were associated with increased idiopathic pneumonia syndrome risk [320]. No standard treatment for post-transplant bronchiolitis obliterans was identified in a systematic review, and treatment categories did not show significant differences in response [393].
Other possible long-term outcomes
A South Korean population study of 985,957 children, including 25,550 hospitalized for acute bronchiolitis, followed participants for 15 years to examine 24 predefined mental-health disorders; the study addressed possible associations regardless of allergic conditions, but the supplied abstract does not provide effect estimates [323]. Climate, community, and geographic variation also influence RSV burden: Queensland surveillance characterized RSV notifications in children younger than 2 years before introduction of the national maternal-and-infant protection program [252]B2b, while Connecticut mapping identified geographic clusters of bronchiolitis emergency visits and hospital discharges before and after the COVID-19 pandemic [395].
| Domain | Examples or evidence |
|---|---|
| Acute severity | Hypoxaemia, prolonged hospitalization, PICU admission, and HFNC use; risk factors include prematurity, congenital heart disease, chronic lung disease, and Down syndrome [396] |
| Prevention | Nirsevimab reduced RSV-LRTIs by 63% in a meta-analysis [250]A1a |
| Chronic respiratory disease | Asthma-related outcomes, BPD-associated morbidity, and bronchiolitis obliterans [243]B3b[313][315][385][393] |
| Transplant-related disease | Bronchiolitis obliterans syndrome and idiopathic pneumonia syndrome after allogeneic HCT [320][393] |
| Safety consideration | Preterm-birth signal during maternal RSVPreF3-Mat vaccine development [224]A1b |
Prognosis & Natural History
- ▸The supplied references do not quantify the complete untreated natural history, typical peak severity, or symptom-resolution timeline of bronchiolitis. [339][348][357][358]
- ▸Escalation to noninvasive or invasive ventilation is a principal acute prognostic outcome in severe bronchiolitis. [339][397]
- ▸Randomized evidence supplied here evaluates prone positioning, HFNC weaning, and **88% versus 92% SpO₂** oxygen thresholds, but the abstracts do not provide their outcome estimates. [339][348][364]
- ▸Lung ultrasound regional abnormalities were studied as potential markers of ventilatory-support need, whereas routine chest radiography was reported not to improve critical-bronchiolitis outcomes. [357][358]
- ▸Hospitalized early-life respiratory viral infection and bronchiolitis have been studied in relation to later asthma and mental-health outcomes, but the supplied abstracts do not provide sufficient estimates to quantify individual risk. [243][323]
Overall prognosis
The supplied evidence base focuses primarily on infants and young children with moderate-to-severe or critical bronchiolitis requiring hospital-level respiratory support; it does not provide a complete description of the untreated illness trajectory, expected day of peak severity, or time to symptom resolution. Prognosis is therefore best understood in terms of respiratory-support escalation, duration of oxygen or high-flow nasal cannula (HFNC) therapy, intensive-care utilization, postdischarge healthcare use, and possible later respiratory or neurodevelopmental associations. [339][348][357][358]
Acute respiratory deterioration and ventilatory support
Infants aged 6 months or younger with moderate-to-severe bronchiolitis requiring HFNC were enrolled in the multicentre PROPOSITIS randomized trial to determine whether prone positioning reduced escalation to noninvasive or invasive ventilation. The supplied abstract identifies this as the primary clinical question but does not report the trial’s outcome data; consequently, prone positioning cannot be described as prognostically beneficial or harmful from the provided evidence. [339]
A 2026 systematic review and meta-analysis evaluated HFNC against continuous positive airway pressure (CPAP) and conventional oxygen therapy in children with acute respiratory failure caused by bronchiolitis, pneumonia, or acute severe asthma. Its prespecified outcomes included treatment failure and safety, but the supplied abstract does not provide pooled estimates; therefore, it does not establish the magnitude of any prognostic advantage of HFNC for bronchiolitis. [397]
A nurse-driven HFNC-weaning randomized trial enrolled infants aged 1–24 months with severe bronchiolitis in two tertiary pediatric intensive-care units. The protocol used structured Wang Bronchiolitis Severity Scores and the ROX index, defined as SpO₂/FiO₂ divided by respiratory rate, to guide weaning; the primary outcome was total HFNC duration, with hospitalization and time to first wean among secondary outcomes. The supplied abstract does not report results, so the effect of protocolized weaning on recovery time or length of stay remains undetermined here. [348]
The OxyKids randomized trial compared oxygen-treatment thresholds of 88% versus 92% SpO₂ in children aged 6 weeks–12 years requiring oxygen for bronchiolitis, lower respiratory tract infection, or acute viral-induced wheeze. Oxygen could be delivered by low-flow or high-flow nasal cannula or face mask, and length of hospital stay was the principal clinical outcome. The supplied abstract does not state whether the lower threshold was noninferior or reduced hospitalization; it therefore cannot support a definitive prognostic threshold recommendation from these data alone. [364]
Markers of severe disease and intensive-care course
In a prospective study of 160 infants with bronchiolitis, lung ultrasound was performed within 12 hours of admission using regional Brat scoring to examine the distribution of pulmonary abnormalities and their relationship to the need for ventilatory support. The supplied abstract confirms that the study compared favorable-outcome and more severe clinical groups but does not provide the regional scores, effect estimates, or predictive performance. [358]
Routine chest radiography was examined retrospectively in children younger than 3 years admitted to pediatric intensive-care, step-down, or cardiac intensive-care settings for critical bronchiolitis. The study compared patients who underwent chest radiography with those who did not, assessing intensive-care length of stay and level of respiratory support; its title reports that routine radiography did not improve outcomes. [357]
Among mechanically ventilated children with bronchiolitis, a retrospective cohort study of 407 patients evaluated iatrogenic withdrawal during intravenous opioid weaning using the Withdrawal Assessment Tool-1. Withdrawal was defined as a score of ≥3; the study examined dose reductions and clinical characteristics, but the supplied abstract does not report the quantitative dose–withdrawal associations. [110]B3b
Longer-term outcomes
A retrospective cohort of 2,628 children hospitalized with acute respiratory infections and tested for respiratory viruses assessed subsequent asthma after early-life human rhinovirus or respiratory syncytial virus infection. The supplied abstract establishes the study’s objective and population but does not provide virus-specific hazard ratios or absolute asthma risks; therefore, it supports concern about possible later asthma associations without quantifying individual prognosis. [243]B3b
A South Korean national cohort included 985,957 children born in 2002–2003, including 25,550 hospitalized for acute bronchiolitis and 102,220 matched unexposed children, followed through December 2021 for 24 predefined mental-health disorders. The supplied abstract indicates that both early- and late-onset outcomes were evaluated but does not report adjusted hazard ratios; no causal mental-health effect should therefore be inferred from the information provided. [323]
Postdischarge burden and family communication
A single-center pediatric study introduced the 30-day ED/READ ratio—the ratio of postdischarge emergency-department visits to readmissions—to characterize diagnosis-specific hospital reuse. Although bronchiolitis was among the diagnoses considered, the supplied abstract does not provide bronchiolitis-specific ratios, so the magnitude of postdischarge reuse cannot be stated. [342]
A Canadian randomized study tested weekly image-based “blogshots” addressing common pediatric conditions, including bronchiolitis, in parents or guardians of children younger than 5 years. The intervention was designed to improve knowledge and manage expectations; the supplied abstract does not report bronchiolitis-specific knowledge or outcome changes. [95]A1b
Prognostic interpretation
Current evidence supplied here supports assessing prognosis dynamically according to respiratory distress, oxygen requirement, need for HFNC or escalation, and response to weaning, while recognizing that several contemporary randomized studies have not supplied outcome data in their abstracts. [339][348][364][397] Long-term associations with asthma and mental-health outcomes remain observational and incompletely quantified in the available summaries. [243]B3b[323]
| Domain | Population or comparison | Outcome addressed | Interpretation from supplied abstract |
|---|---|---|---|
| Ventilatory escalation | Infants ≤6 months on HFNC; prone versus usual positioning | Escalation to noninvasive or invasive ventilation | Trial question reported; results not supplied. [339] |
| Oxygen strategy | Children 6 weeks–12 years; 88% versus 92% SpO₂ thresholds | Length of hospital stay and safety | Trial design reported; results not supplied. [364] |
| HFNC recovery | Infants 1–24 months with severe bronchiolitis | HFNC duration and hospitalization | Protocol and outcomes specified; results not supplied. [348] |
| Disease severity assessment | 160 infants; regional lung-ultrasound scoring | Need for ventilatory support | Association was investigated; effect estimates not supplied. [358] |
| Long-term association | Early-life HRV or RSV infection | Subsequent asthma | Cohort study reported; virus-specific risks not supplied. [243]B3b |
| Long-term association | 25,550 children hospitalized with bronchiolitis versus matched controls | Mental-health disorders through 2021 | Outcomes were assessed; hazard ratios not supplied. [323] |
Special Populations
- ▸Evidence on prone positioning and HFNC weaning specifically concerns infants with moderate-to-severe or severe bronchiolitis; the supplied PROPOSITIS abstract states the trial objective and design but not its results. [339][348]
- ▸The OxyKids trial directly compares **88% versus 92% SpO₂** oxygen thresholds across children aged 6 weeks–12 years, but the supplied abstract does not report outcomes. [364]
- ▸Children with Down syndrome, critical illness, PICU admission, or suspected septic shock require population-specific risk assessment; available studies are observational or pilot investigations. [341][68][312][399]
- ▸Nirsevimab prevention evidence cited here comes from a single-center retrospective cohort, while environmental exposures and later asthma are supported by observational cohort studies. [55][54][243]
- ▸Hydration, acid-suppressive medication exposure, parental education, and health-system disparities are important special-population considerations but require attention to study exclusions, confounding, and generalizability. [401][242][402][95][345]
Young infants and age-related risk
Bronchiolitis is primarily a disease of infancy, and the available interventional evidence is concentrated in infants requiring respiratory support. The PROPOSITIS randomized clinical trial enrolled infants aged ≤6 months with moderate-to-severe acute bronchiolitis who had been admitted for ≤24 hours and required high-flow nasal cannula (HFNC) support; it evaluated whether prone positioning reduced escalation to noninvasive or invasive ventilation. [339] A separate randomized trial studied infants aged 1–24 months with severe bronchiolitis requiring HFNC and evaluated a nurse-driven weaning protocol based on the Wang Bronchiolitis Severity Score and ROX index. [348]
The OxyKids randomized trial included children aged 6 weeks–12 years requiring oxygen for bronchiolitis, lower respiratory tract infection, or acute viral-induced wheeze. Participants were assigned to an oxygen-treatment threshold of 88% versus 92% SpO₂, with oxygen delivered by low-flow or high-flow nasal cannula or face mask. [364] The study was designed to determine whether the lower threshold could safely reduce hospital length of stay; the supplied abstract does not report the clinical results, so the threshold should not be interpreted as an established universal target on the basis of this citation alone. [364]
Severe disease, HFNC, and intensive-care populations
In infants with severe bronchiolitis, a nurse-driven HFNC-weaning protocol used structured serial assessment with the Wang Bronchiolitis Severity Score and ROX index, with trained nurses initiating weaning according to predefined criteria; reported outcomes included HFNC duration, time to first wean, and hospitalization. [348] A separate Italian quality-improvement project addressed children aged <24 months treated with HFNC, including initiation, flow titration, escalation, and a PICU-alert system for deterioration during the first 72 hours of hospitalization. [349]C Because this was a quality-improvement project rather than a randomized efficacy trial, its findings primarily address protocol feasibility, adherence, and implementation. [349]C
Retrospective ward-based data concerned children aged <24 months receiving HFNC at ≥0.5 L/kg/min and examined trajectories associated with PICU transfer and escalation beyond HFNC. [400] These data are useful for triage, but the observational design cannot establish that identified factors cause deterioration or that a particular HFNC strategy improves outcomes. [400] In a prospective pilot study of 46 PICU patients aged <12 months, point-of-care echocardiography assessed right-ventricular systolic function using TAPSE at PICU admission in relation to length of stay and respiratory-support duration. [399]C A prospective cohort of 42 children with critical bronchiolitis and nine healthy controls measured nasal cytokines and compared inflammatory profiles according to RSV, rhinovirus, or polyviral infection and clinical risk factors. [312]C These studies support investigation of cardiopulmonary and host-inflammatory heterogeneity but do not establish routine echocardiography or cytokine testing for clinical care. [399]C[312]C
Children with Down syndrome and other medical vulnerability
Children with Down syndrome have been studied as a distinct high-risk population because respiratory illnesses are associated with increased hospitalization and intensive-care use. A retrospective cohort of 2,327 children with Down syndrome examined which co-occurring diagnoses were associated with respiratory-related hospital admission and ICU support across childhood. [341] The citation supports targeted risk assessment in this population, although the supplied abstract does not provide the specific diagnoses or effect estimates.
For children with RSV bronchiolitis admitted to the PICU, a retrospective cohort of 224 patients developed and internally validated a prediction model for septic shock using routine blood biomarkers and concomitant fungal infection. [68]B2b This model is intended for early risk identification, but internal validation alone does not demonstrate transportability to other hospitals or populations. [68]B2b
Prevention, exposures, and longer-term outcomes
Nirsevimab is described as a recombinant monoclonal antibody recommended for all infants and high-risk children aged <24 months. A single-center Italian cohort compared bronchiolitis presentations during consecutive RSV seasons before and after its introduction and evaluated effects on emergency-department epidemiology, including admissions. [55]B2b The retrospective, single-center design limits causal inference regarding population-wide effectiveness. [55]B2b
Environmental risk has also been examined prospectively. In 1,124 mother–child pairs from tropical Singapore, monthly meteorological conditions and outdoor air-quality exposures were linked to first occurrence of eczema, wheeze, and bronchiolitis from the prenatal period through age 8 years using adjusted Poisson regression. [54]B2b These findings address associations across development rather than immediate treatment of an acute bronchiolitis episode. [54]B2b
Early-life infection may have implications beyond the acute illness. A retrospective cohort of 2,628 children hospitalized with acute respiratory infection and tested for respiratory viruses evaluated subsequent asthma after early human rhinovirus or RSV infection, with particular attention to infection timing. [243]B3b The cohort design identifies associations, not proof that either virus independently causes asthma. [243]B3b
Feeding, medications, families, and health-system context
For hospitalized children aged 2–23 months with bronchiolitis, an observational multicenter substudy evaluated nasogastric versus intravenous fluid replacement and its relationship to clinical factors and outcomes; children with extreme prematurity, apnea, cyanosis, or comorbid conditions were excluded. [401] The study therefore informs hydration practice in a selected inpatient population and should not automatically be generalized to medically complex or unstable infants. [401]
Early acid suppression is a potentially modifiable exposure. A birth cohort followed 200 children with complete data to 24 months and examined proton-pump-inhibitor exposure during the first 6 months and respiratory-tract infections. [242]B2b A much larger Taiwanese claims analysis evaluated prenatal and childhood proton-pump-inhibitor or histamine-2-receptor-antagonist exposure in relation to hospitalization for serious infections, using antacid exposure as an active comparator. [402] Both studies are observational and cannot prove that acid-suppressive treatment causes infection; prescribing should therefore be based on a clear indication rather than bronchiolitis prevention. [242]B2b[402]
Parents or legal guardians of children aged <5 years participated in a Canadian randomized and qualitative study of image-based digital “blogshots.” One intervention set included bronchiolitis alongside other Choosing Wisely Canada topics and aimed to improve knowledge and manage expectations about recommended care. [95]A1b Finally, national general-hospital data examined disparities in bronchiolitis care quality and outcomes during three winter periods from 2019–2022, using pretrial data from a pathway-implementation trial. [345] These studies emphasize the importance of communication, expectation management, equitable evidence-based care, and context-sensitive implementation. [95]A1b[345]
| Population or issue | Evidence and scope |
|---|---|
| Infants ≤6 months on HFNC | Randomized trial of prone positioning and escalation to noninvasive or invasive ventilation. [339] |
| Infants 1–24 months with severe bronchiolitis | Randomized evaluation of nurse-driven HFNC weaning using WBSS and ROX index. [348] |
| Children 6 weeks–12 years receiving oxygen | Randomized comparison of 88% versus 92% SpO₂ thresholds. [364] |
| Children with Down syndrome | Retrospective cohort examining respiratory-related admission and ICU support. [341] |
| PICU patients with RSV bronchiolitis | Prediction model for septic shock using routine biomarkers and concomitant fungal infection. [68]B2b |
| Infants and young children | Nirsevimab cohort, environmental-exposure cohort, and later-asthma cohort evidence. [55]B2b[54]B2b[243]B3b |
| Hospitalized children 2–23 months | Observational evaluation of nasogastric versus intravenous hydration. [401] |
| Families and general hospitals | Digital parent education and disparity-focused quality-of-care studies. [95]A1b[345] |
Prevention, Screening & Surveillance
- ▸Nirsevimab is the principal infant-focused RSV prevention strategy in the cited evidence; observational studies report substantial reductions in bronchiolitis admissions, including 60%–80% in Spain. [55,406]
- ▸Timely, high-coverage implementation matters because incomplete regional delivery has been associated with preventable RSV and bronchiolitis burden. [403-405]
- ▸Maternal RSVPreF3-Mat evidence requires caution because a phase 3 trial was stopped after an increased preterm-birth risk was observed in another trial. [224]
- ▸Surveillance should include RSV, human metapneumovirus and adenovirus, and should monitor severe outcomes, intensive-care use and prolonged hospitalisation. [51,52,57,318]
- ▸Post-hospitalisation follow-up should be individualised; transplant recipients require pulmonary-function surveillance for bronchiolitis obliterans syndrome. [315,323,404]
- ▸Hospital oxygen protocols are being reassessed using randomised evidence comparing 88% and 92% SpO2 thresholds. [364]
Prevention of acute bronchiolitis
Respiratory syncytial virus (RSV) is the principal pathogen associated with bronchiolitis in infancy and remains an important cause of emergency-department attendance, hospitalisation and intensive-care use in children younger than 24 months. [55]B2b A global systematic review of 539 studies and 584 datasets found that RSV was frequently detected among children with respiratory-tract infections, with estimates varying according to age, geography, clinical setting, sampling period and disease category. [51]B2a Prevention should therefore prioritise infants during their first RSV season and children with conditions associated with severe disease. [57]B2b
Nirsevimab is a long-acting monoclonal antibody recommended for all infants and for high-risk children younger than 24 months. [55]B2b Post-implementation observational evidence supports an important population effect, although the magnitude varies by setting and programme delivery. In Spain, universal prophylaxis was associated with a reported 60%–80% reduction in bronchiolitis hospital admissions. [406] Italian studies evaluated reductions in bronchiolitis diagnoses, hospitalisations, severity and respiratory-support requirements after introduction of nirsevimab, including cohorts from Sicily and the Lazio primary-care system. [321][355] A single-centre Italian emergency-department cohort compared two consecutive RSV seasons before and after implementation, while national Italian data examined regional variation in rollout timing, organisational models, logistical barriers, hospitalisations and paediatric intensive-care admissions. [55]B2b[394] These findings support high and timely coverage, but the available evidence is predominantly observational and may be affected by differences in eligibility, season intensity, healthcare-seeking behaviour and regional implementation. [55]B2b[394]
Incomplete or delayed implementation can substantially limit programme benefit. In an Italian pre-implementation cohort of 780 newborns, 84 infants developed acute bronchiolitis, 45 had RSV-positive disease, 44 were hospitalised and 7 required paediatric intensive care; among hospitalised infants, 31 had RSV infection. [403] The same report highlighted suboptimal coverage during the first implementation season. [403] Regional analyses emphasised that RSV admission burden is concentrated in infancy and follows a marked seasonal pattern, making birth-season planning, antenatal coordination and rapid access to prophylaxis important components of prevention. [405] Primary-care surveillance in the Veneto region also assessed changes in bronchiolitis-related contacts and healthcare use after nirsevimab introduction. [324]
Maternal RSV immunisation is another preventive strategy because transplacentally transferred antibody can protect infants after birth. [224]A1b However, a phase 3 randomised placebo-controlled trial of RSVPreF3-Mat in high-risk pregnant women was stopped and unblinded after an increased risk of preterm birth associated with the vaccine had been observed in a separate trial in healthy pregnant women. [224]A1b Until safety and regulatory recommendations are clarified, maternal vaccination should be discussed using current national guidance and with explicit consideration of gestational age, maternal risk and available infant prophylaxis. [224]A1b
Risk-based prevention and case finding
Risk assessment should identify prematurity, major congenital heart disease, chronic lung disease of prematurity and Down syndrome, particularly in children aged 12–23 months who may remain vulnerable during the second year of life. [396] A nationwide Swedish cohort assessed RSV-associated death, intensive-care admission and prolonged hospitalisation of ≥7 days in children aged 0–18 years using national registers, providing a framework for population surveillance of severe outcomes. [57]B2b The burden also extends beyond hospital discharge: a prospective Dutch national study recorded the clinical and adverse-event burden of RSV-related paediatric intensive-care admission during infancy and assessed post-traumatic stress symptoms in parents. [284]B2b
Bronchiolitis surveillance should not be restricted to RSV. Human metapneumovirus was detected in 4.56% of Chinese children aged 0–14 years across 78 studies including 334,901 participants, with the highest detection rate in 1-year-olds (6.02%); no meaningful sex difference was reported. [52]B2a Adenovirus surveillance detected an outbreak of severe acute respiratory infection in Brazil and Colombia during late 2022, with molecular characterisation showing predominance of adenovirus C in the reported outbreak analysis. [318] These data support maintaining laboratory and syndromic surveillance for non-RSV viruses, especially when seasonal activity or disease severity is unusual. [52]B2a[318]
Surveillance after bronchiolitis and high-risk therapies
Routine long-term screening of every child after uncomplicated acute bronchiolitis is not established by the cited evidence. Nevertheless, follow-up may be appropriate when there are persistent respiratory symptoms, recurrent healthcare use, underlying disease or severe hospitalisation. A large South Korean population study followed 985,957 children for up to 15 years and compared 25,550 children hospitalised for bronchiolitis with a matched unexposed cohort to evaluate later mental-health outcomes, including disorders before and after age 10 years. [323] A nationwide Israeli cohort similarly compared asthma-related healthcare utilisation after infant hospitalisation for RSV lower-respiratory-tract infection with utilisation after lower-respiratory-tract infection caused by other respiratory viruses. [315] These studies justify clinical awareness of possible longer-term respiratory and psychosocial needs, but they do not establish universal screening protocols. [315][323]
Children and young adults after allogeneic haematopoietic stem-cell transplantation require a distinct surveillance pathway for bronchiolitis obliterans syndrome. Pulmonary-function testing before and after transplantation may detect disease before symptoms, but a systematic review found variation in recommended tests and timing and was undertaken to inform American Thoracic Society guidance. [404] Surveillance should therefore follow transplant-specific protocols and include serial pulmonary assessment when feasible, rather than relying only on symptom-triggered evaluation. [404]
Oxygen monitoring during respiratory distress
In hospitalised children receiving oxygen for bronchiolitis, lower-respiratory-tract infection or acute viral-induced wheeze, the OxyKids multicentre randomised trial directly compared an oxygen-treatment threshold of 88% with 92% peripheral oxygen saturation. [364] The trial was designed to determine whether the lower threshold could reduce hospital stay without compromising safety and included children aged 6 weeks–12 years across ten Dutch hospitals. [364] Until complete outcome interpretation is incorporated into local protocols, oxygen initiation, weaning and discharge decisions should follow validated institutional guidance rather than applying a lower threshold indiscriminately. [364]
| Priority | Evidence-based focus |
|---|---|
| Infant RSV prevention | Nirsevimab for all infants and high-risk children younger than 24 months, with attention to timely and equitable delivery. [55]B2b[403][394] |
| Maternal prevention | RSVPreF3-Mat has passive-transfer rationale, but preterm-birth safety concerns require guidance-based use. [224]A1b |
| Severe-disease surveillance | Track ICU/PICU admission, death and prolonged hospitalisation, including hospitalisation of ≥7 days. [57]B2b[284]B2b |
| Viral surveillance | Monitor RSV, HMPV and adenovirus, particularly during atypical seasons or outbreaks. [51]B2a[52]B2a[318] |
| Transplant surveillance | Use serial pulmonary-function testing before and after allogeneic HSCT according to specialist protocols. [404] |
| Oxygen monitoring | Apply local protocols while evidence comparing 88% and 92% SpO2 thresholds is incorporated. [364] |
References
- [1]
McDaniel CE, Ralston S, Lucas B et al.. “Association of Diagnostic Criteria With Urinary Tract Infection Prevalence in Bronchiolitis: A Systematic Review and Meta-analysis.” JAMA pediatrics (2019). PMID: 30688987 ↗
L1SR_OBSCited in: Definition, Classification & Nomenclature, Diagnosis & Workup - [2]
Brooks CG, Harrison WN, Ralston SL. “Association Between Hypertonic Saline and Hospital Length of Stay in Acute Viral Bronchiolitis: A Reanalysis of 2 Meta-analyses.” JAMA pediatrics (2016). PMID: 27088767 ↗
L2SR_OBSCited in: Definition, Classification & Nomenclature, Clinical Presentation, Diagnosis & Workup, Long-term & Definitive Management - [3]
Fujiogi M, Goto T, Yasunaga H et al.. “Trends in Bronchiolitis Hospitalizations in the United States: 2000-2016.” Pediatrics (2019). PMID: 31699829 ↗
L2OTHERCited in: Definition, Classification & Nomenclature, Epidemiology, Etiology & Risk Factors - [4]
Wolf ER, Richards A, Lavallee M et al.. “Patient, Provider, and Health Care System Characteristics Associated With Overuse in Bronchiolitis.” Pediatrics (2021). PMID: 34556548 ↗
L2OTHERCited in: Definition, Classification & Nomenclature, Diagnosis & Workup - [5]
Hasegawa K, Tsugawa Y, Brown DF et al.. “Trends in bronchiolitis hospitalizations in the United States, 2000-2009.” Pediatrics (2013). PMID: 23733801 ↗
L2OTHERCited in: Definition, Classification & Nomenclature - [6]
Pelletier AJ, Mansbach JM, Camargo CA. “Direct medical costs of bronchiolitis hospitalizations in the United States.” Pediatrics (2006). PMID: 17142527 ↗
L2OTHERCited in: Definition, Classification & Nomenclature - [7]
Parikh K, Hall M, Mittal V et al.. “Establishing benchmarks for the hospitalized care of children with asthma, bronchiolitis, and pneumonia.” Pediatrics (2014). PMID: 25136044 ↗
L2OTHERCited in: Definition, Classification & Nomenclature - [8]
Shanthikumar S, Gower WA, Srinivasan S et al.. “Detection of Bronchiolitis Obliterans Syndrome after Pediatric Hematopoietic Stem Cell Transplantation: An Official American Thoracic Society Clinical Practice Guideline.” American journal of respiratory and critical care medicine (2024). PMID: 38889365 ↗
L1GUIDELINECited in: Definition, Classification & Nomenclature, Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management - [9]
Ahrens KA, Janevic T, Strumpf EC et al.. “Paid Family Leave and Prevention of Acute Respiratory Infections in Young Infants.” JAMA pediatrics (2024). PMID: 39186259 ↗
L2OTHERCited in: Definition, Classification & Nomenclature - [10]
Ramsden V, Babl FE, Haskell L et al.. “Sustainability of the de-implementation of low-value care in infants with bronchiolitis: 2-year follow-up of a cluster randomised controlled trial.” BMJ quality & safety (2026). PMID: 40651808 ↗
L2RCTCited in: Definition, Classification & Nomenclature, Long-term & Definitive Management - [11]
Ramsden V, Babl FE, Dalziel SR et al.. “Sustainability of evidence-based practices in the management of infants with bronchiolitis in hospital settings - a PREDICT study protocol.” BMC health services research (2022). PMID: 36038929 ↗
L5TRIAL_NONRANDOMCited in: Definition, Classification & Nomenclature - [12]
Wang CN, Huttner BD, Magrini N et al.. “Pediatric Antibiotic Prescribing in China According to the 2019 World Health Organization Access, Watch, and Reserve (AWaRe) Antibiotic Categories.” The Journal of pediatrics (2020). PMID: 32093934 ↗
L2OTHERCited in: Definition, Classification & Nomenclature - [13]
Brossier DW, Cerasuolo D, Briant AR et al.. “Caffeine and other methylxanthines' impact on bronchiolitis-related apnea in under 12-months-old children-a systematic review with meta-analyses.” European journal of pediatrics (2026). PMID: 41653310 ↗
L1SR_OBSCited in: Definition, Classification & Nomenclature, Special Populations - [14]
Manti S, Gambadauro A, Ruggeri P et al.. “Application of the TIDieR checklist to improve the HFNC use in bronchiolitis management.” European journal of pediatrics (2024). PMID: 39690333 ↗
L2SR_OBSCited in: Definition, Classification & Nomenclature - [15]
Green CA, Yeates D, Goldacre A et al.. “Admission to hospital for bronchiolitis in England: trends over five decades, geographical variation and association with perinatal characteristics and subsequent asthma.” Archives of disease in childhood (2015). PMID: 26342094 ↗
L2OTHERCited in: Definition, Classification & Nomenclature, Epidemiology, Etiology & Risk Factors, Special Populations - [16]
Foley DA, Phuong LK, Peplinski J et al.. “Examining the interseasonal resurgence of respiratory syncytial virus in Western Australia.” Archives of disease in childhood (2021). PMID: 34433552 ↗
L3OTHERCited in: Definition, Classification & Nomenclature, Clinical Presentation - [17]
Armarego M, Forde H, Wills K et al.. “High-flow nasal cannula therapy for infants with bronchiolitis.” The Cochrane database of systematic reviews (2024). PMID: 38506440 ↗
L1SR_OBSCited in: Definition, Classification & Nomenclature, Diagnosis & Workup, Long-term & Definitive Management, Complications - [18]
Zhang L, Mendoza-Sassi RA, Wainwright C et al.. “Nebulised hypertonic saline solution for acute bronchiolitis in infants.” The Cochrane database of systematic reviews (2017). PMID: 29265171 ↗
L1SR_OBSCited in: Definition, Classification & Nomenclature, Long-term & Definitive Management - [19]
Garcia-Mauriño C, Moore-Clingenpeel M, Wallihan R et al.. “Discharge Criteria for Bronchiolitis: An Unmet Need.” The Pediatric infectious disease journal (2018). PMID: 29189658 ↗
L2OTHERCited in: Definition, Classification & Nomenclature, Epidemiology, Etiology & Risk Factors, Special Populations - [20]
Resch B, Puchas C, Resch E et al.. “Epidemiology of Respiratory Syncytial Virus-related Hospitalizations and the Influence of Viral Coinfections in Southern Austria in a 7-year Period.” The Pediatric infectious disease journal (2020). PMID: 31651808 ↗
L3OTHERCited in: Definition, Classification & Nomenclature, History and Evolution of Treatment - [21]
Jartti T, Lehtinen P, Vuorinen T et al.. “Bronchiolitis: age and previous wheezing episodes are linked to viral etiology and atopic characteristics.” The Pediatric infectious disease journal (2009). PMID: 19258922 ↗
L2OTHERCited in: Definition, Classification & Nomenclature, History and Evolution of Treatment, Special Populations - [22]
Muñoz-Quiles C, López-Lacort M, Úbeda-Sansano I et al.. “Population-based Analysis of Bronchiolitis Epidemiology in Valencia, Spain.” The Pediatric infectious disease journal (2016). PMID: 26658376 ↗
L3OTHERCited in: Definition, Classification & Nomenclature - [23]
Piedra PA, Mansbach JM, Jewell AM et al.. “Bordetella pertussis is an uncommon pathogen in children hospitalized with bronchiolitis during the winter season.” The Pediatric infectious disease journal (2015). PMID: 25970109 ↗
L2OTHERCited in: Definition, Classification & Nomenclature, Diagnosis & Workup - [24]
Kakimoto Y, Seto Y, Ochiai E et al.. “Cytokine Elevation in Sudden Death With Respiratory Syncytial Virus: A Case Report of 2 Children.” Pediatrics (2016). PMID: 27940684 ↗
L4CASE_REPORTCited in: Pathophysiology & Developmental Mechanism, Complications - [25]
Balekian DS, Linnemann RW, Castro VM et al.. “Pre-birth cohort study of atopic dermatitis and severe bronchiolitis during infancy.” Pediatric allergy and immunology : official publication of the European Society of Pediatric Allergy and Immunology (2016). PMID: 26766307 ↗
L2COHORTCited in: Pathophysiology & Developmental Mechanism - [26]
Manti S, Cuppari C, Lanzafame A et al.. “Detection of respiratory syncytial virus (RSV) at birth in a newborn with respiratory distress.” Pediatric pulmonology (2017). PMID: 28834426 ↗
L4CASE_REPORTCited in: Pathophysiology & Developmental Mechanism - [27]
Piedimonte G, Harford TJ. “Effects of maternal-fetal transmission of viruses and other environmental agents on lung development.” Pediatric research (2019). PMID: 31698410 ↗
L5REVIEW_NARRATIVECited in: Pathophysiology & Developmental Mechanism - [28]
Vu LD, Saravia J, Jaligama S et al.. “Deficiency in ST2 signaling ameliorates RSV-associated pulmonary hypertension.” American journal of physiology. Heart and circulatory physiology (2021). PMID: 34170196 ↗
L5OTHERCited in: Pathophysiology & Developmental Mechanism - [29]
Ackermann MR. “Lamb model of respiratory syncytial virus-associated lung disease: insights to pathogenesis and novel treatments.” ILAR journal (2014). PMID: 24936027 ↗
L5REVIEW_NARRATIVECited in: Pathophysiology & Developmental Mechanism - [30]
Arkwright PD, Abinun M. “Recently identified factors predisposing children to infectious diseases.” Current opinion in infectious diseases (2008). PMID: 18448964 ↗
L5REVIEW_NARRATIVECited in: Pathophysiology & Developmental Mechanism - [31]
. “Diagnosis and management of bronchiolitis.” Pediatrics (2006). PMID: 17015575 ↗
L1GUIDELINECited in: Epidemiology, Etiology & Risk Factors, Diagnosis & Workup, Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Special Populations, Prevention, Screening & Surveillance - [32]
. “Updated guidance for palivizumab prophylaxis among infants and young children at increased risk of hospitalization for respiratory syncytial virus infection.” Pediatrics (2014). PMID: 25070315 ↗
L1GUIDELINECited in: Epidemiology, Etiology & Risk Factors, Prognosis & Natural History - [33]
. “Updated guidance for palivizumab prophylaxis among infants and young children at increased risk of hospitalization for respiratory syncytial virus infection.” Pediatrics (2014). PMID: 25070304 ↗
L1GUIDELINECited in: Epidemiology, Etiology & Risk Factors, History and Evolution of Treatment, Prognosis & Natural History - [34]
Zhao S, Shang Y, Yin Y et al.. “Ziresovir in Hospitalized Infants with Respiratory Syncytial Virus Infection.” The New England journal of medicine (2024). PMID: 39321361 ↗
L1RCTCited in: Epidemiology, Etiology & Risk Factors, Clinical Presentation, Severity Grading, Staging & Risk Stratification, Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Special Populations - [35]
Bloemers BL, van Furth AM, Weijerman ME et al.. “Down syndrome: a novel risk factor for respiratory syncytial virus bronchiolitis--a prospective birth-cohort study.” Pediatrics (2007). PMID: 17908728 ↗
L2COHORTCited in: Epidemiology, Etiology & Risk Factors - [36]
Birch EE, Khoury JC, Berseth CL et al.. “The impact of early nutrition on incidence of allergic manifestations and common respiratory illnesses in children.” The Journal of pediatrics (2010). PMID: 20227721 ↗
L1RCTCited in: Epidemiology, Etiology & Risk Factors, Diagnosis & Workup, Growth, Development & Nutrition Impact - [37]
Ochoa TJ, Zegarra J, Bellomo S et al.. “Randomized Controlled Trial of Bovine Lactoferrin for Prevention of Sepsis and Neurodevelopment Impairment in Infants Weighing Less Than 2000 Grams.” The Journal of pediatrics (2020). PMID: 32037149 ↗
L1RCTCited in: Epidemiology, Etiology & Risk Factors, History and Evolution of Treatment, Growth, Development & Nutrition Impact, Prognosis & Natural History, Prevention, Screening & Surveillance - [38]
Sismanlar T, Aslan AT, Turktas H et al.. “Respiratory Bronchiolitis-Associated Interstitial Lung Disease in Childhood: New Sequela of Smoking.” Pediatrics (2015). PMID: 26347438 ↗
L4CASE_REPORTCited in: Epidemiology, Etiology & Risk Factors, Growth, Development & Nutrition Impact - [39]
Skirrow H, Wincott T, Cecil E et al.. “Preschool respiratory hospital admissions following infant bronchiolitis: a birth cohort study.” Archives of disease in childhood (2019). PMID: 30842095 ↗
L2COHORTCited in: Epidemiology, Etiology & Risk Factors, Complications, Special Populations - [40]
Coon ER, Young PC, Quinonez RA et al.. “Update on Pediatric Overuse.” Pediatrics (2017). PMID: 28049113 ↗
L5REVIEW_NARRATIVECited in: Epidemiology, Etiology & Risk Factors, Special Populations - [41]
Baillie VL, Olwagen CP, Madhi SA. “Review on Clinical and Molecular Epidemiology of Human Rhinovirus-Associated Lower Respiratory Tract Infections in African and Southeast Asian Children.” The Pediatric infectious disease journal (2018). PMID: 29893746 ↗
L2SR_OBSCited in: Epidemiology, Etiology & Risk Factors, Special Populations, Prevention, Screening & Surveillance - [42]
Vihikangas T, Palmu S, Koivisto AM et al.. “Changes in Bronchiolitis Incidence During the Last Two Decades in Tampere, Finland: A Retrospective Study.” The Pediatric infectious disease journal (2022). PMID: 35895894 ↗
L2COHORTCited in: Epidemiology, Etiology & Risk Factors, Diagnosis & Workup, Special Populations - [43]
Wang YC, Tsai CS, Yang YH et al.. “Association Between Enterovirus Infection and Asthma in Children: A 16-year Nationwide Population-based Cohort Study.” The Pediatric infectious disease journal (2018). PMID: 29373474 ↗
L2COHORTCited in: Epidemiology, Etiology & Risk Factors, Complications - [44]
Coon ER, Young PC, Quinonez RA et al.. “2017 Update on Pediatric Medical Overuse: A Review.” JAMA pediatrics (2018). PMID: 29582079 ↗
L5REVIEW_NARRATIVECited in: Epidemiology, Etiology & Risk Factors, Growth, Development & Nutrition Impact, Special Populations - [45]
Hansel TT, Johnston SL, Openshaw PJ. “Microbes and mucosal immune responses in asthma.” Lancet (London, England) (2013). PMID: 23428115 ↗
L5REVIEW_NARRATIVECited in: Epidemiology, Etiology & Risk Factors, Special Populations - [46]
Morikawa Y, Morimoto K, Kodani T et al.. “Safety and efficacy of a helium-oxygen mix for pediatric respiratory failure associated with anatomical and functional stenotic lesions of the airway: a phase II clinical trial.” Respiratory medicine (2025). PMID: 41412268 ↗
L4TRIAL_NONRANDOMCited in: Epidemiology, Etiology & Risk Factors, Diagnosis & Workup - [47]
Doumat G, Mehta GD, Espinola JA et al.. “Race-Neutral Equations and Pulmonary Function Test Interpretation in Two Pediatric Cohorts.” The Journal of pediatrics (2024). PMID: 38815738 ↗
L2OTHERCited in: Epidemiology, Etiology & Risk Factors, Severity Grading, Staging & Risk Stratification, Growth, Development & Nutrition Impact - [48]
Schuh S, Kwong JC, Holder L et al.. “Predictors of Critical Care and Mortality in Bronchiolitis after Emergency Department Discharge.” The Journal of pediatrics (2018). PMID: 29747934 ↗
L2OTHERCited in: Epidemiology, Etiology & Risk Factors, Clinical Presentation - [49]
Deschamps J, Boucekine M, Fayol L et al.. “Neighborhood Disadvantage and Early Respiratory Outcomes in Very Preterm Infants with Bronchopulmonary Dysplasia.” The Journal of pediatrics (2021). PMID: 34216631 ↗
L2OTHERCited in: Epidemiology, Etiology & Risk Factors - [50]
Laugier O, Garcia P, Boucékine M et al.. “Influence of Socioeconomic Context on the Rehospitalization Rates of Infants Born Preterm.” The Journal of pediatrics (2017). PMID: 28893384 ↗
L2OTHERCited in: Epidemiology, Etiology & Risk Factors - [51]
Khales P, Razizadeh MH, Ghorbani S et al.. “The prevalence and role of human respiratory syncytial virus in pediatric respiratory tract infections: a systematic review and meta-analysis of global data.” EClinicalMedicine (2026). PMID: 41908856 ↗
L2SR_OBSCited in: Epidemiology, Etiology & Risk Factors, Prevention, Screening & Surveillance - [52]
Pang Z, Guo N, Han L et al.. “Epidemiological characteristics and clinical correlations of human metapneumovirus (HMPV) infection in children aged 0-14 years in China: a systematic review and meta-analysis.” BMC public health (2026). PMID: 41527080 ↗
L2SR_OBSCited in: Epidemiology, Etiology & Risk Factors, Special Populations, Prevention, Screening & Surveillance - [53]
Cozzi G, Cortellazzo Wiel L, Amaddeo A et al.. “Prevalence of SARS-CoV-2 positivity in infants with bronchiolitis: a multicentre international study.” Archives of disease in childhood (2022). PMID: 35705371 ↗
L4OTHERCited in: Epidemiology, Etiology & Risk Factors, Clinical Presentation, History and Evolution of Treatment, Prognosis & Natural History - [54]
Aik J, Lau HX, Woo M et al.. “Meteorological, ozone, maternal and individual-level risk factors for childhood diseases in Singapore: A prospective birth cohort study from 2009 to 2019.” Ecotoxicology and environmental safety (2026). PMID: 42066443 ↗
L2COHORTCited in: Epidemiology, Etiology & Risk Factors, Special Populations - [55]
Castagno E, Aschieri C, Ferri I et al.. “Epidemiological Impact of Nirsevimab on Admissions for Bronchiolitis in a Pediatric Emergency Department: A Single-Center Cohort Study.” Viruses (2026). PMID: 42043258 ↗
L2COHORTCited in: Epidemiology, Etiology & Risk Factors, Special Populations, Prevention, Screening & Surveillance - [56]
Meyer SIR, Albertsen BK, Skipper MT et al.. “Pulmonary Function Deficit and Clinical Associations in Childhood Acute Lymphoblastic Leukaemia Survivors: A National Retrospective ALL-STAR Lungs Cohort Study.” Pediatric pulmonology (2026). PMID: 41969139 ↗
L2COHORTCited in: Epidemiology, Etiology & Risk Factors, Diagnosis & Workup, Prognosis & Natural History - [57]
Dallagiacoma G, Lundholm C, Smew AI et al.. “Risk factors for severe outcomes of respiratory syncytial virus infection in children: a nationwide cohort study in Sweden.” The Lancet regional health. Europe (2025). PMID: 41262420 ↗
L2COHORTCited in: Epidemiology, Etiology & Risk Factors, Prevention, Screening & Surveillance - [58]
Ma HY, Lin IF, Liu YC et al.. “Risk Factors for Severe Respiratory Syncytial Virus Infection in Hospitalized Children.” The Pediatric infectious disease journal (2024). PMID: 38295229 ↗
L2OTHERCited in: Epidemiology, Etiology & Risk Factors, Special Populations - [59]
Daniels D, Wang D, Suryadevara M et al.. “Epidemiology of RSV Bronchiolitis Among Young Children in Central New York Before and After the Onset of the COVID-19 Pandemic.” The Pediatric infectious disease journal (2023). PMID: 37725814 ↗
L2OTHERCited in: Epidemiology, Etiology & Risk Factors, Prevention, Screening & Surveillance - [60]
Totapally BR, Totapalli S, Sendi P et al.. “Epidemiology of Adenovirus Infection in Hospitalized Children in the United States From 1997 to 2019.” The Pediatric infectious disease journal (2024). PMID: 38621167 ↗
L4OTHERCited in: Epidemiology, Etiology & Risk Factors, Clinical Presentation, Prognosis & Natural History - [61]
Franklin D, Babl FE, Neutze J et al.. “Predictors of Intensive Care Admission in Hypoxemic Bronchiolitis Infants, Secondary Analysis of a Randomized Trial.” The Journal of pediatrics (2022). PMID: 36528052 ↗
L2RCTCited in: Clinical Presentation, Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [62]
Jaquet-Pilloud R, Verga ME, Russo M et al.. “Nebulised hypertonic saline in moderate-to-severe bronchiolitis: a randomised clinical trial.” Archives of disease in childhood (2019). PMID: 31488402 ↗
L1RCTCited in: Clinical Presentation, Diagnosis & Workup, Long-term & Definitive Management, History and Evolution of Treatment - [63]
Viehl L, Estabrook M, Bhalla S et al.. “First Time Wheezing in a 2-Year-Old.” Pediatrics (2021). PMID: 34158315 ↗
L4CASE_REPORTCited in: Clinical Presentation, Diagnosis & Workup - [64]
Shanahan KH, Monuteaux MC, Nagler J et al.. “Early Use of Bronchodilators and Outcomes in Bronchiolitis.” Pediatrics (2021). PMID: 34230092 ↗
L2OTHERCited in: Clinical Presentation - [65]
Lew A, House S, Flaherty B et al.. “Trends in Lower Respiratory Tract Diagnoses and Nonrecommended Bronchiolitis Therapies.” Pediatrics (2025). PMID: 41151618 ↗
L2OTHERCited in: Clinical Presentation - [66]
Cheuk DK, Tang IW, Chan KH et al.. “Rhinovirus infection in hospitalized children in Hong Kong: a prospective study.” The Pediatric infectious disease journal (2007). PMID: 17984805 ↗
L2COHORTCited in: Clinical Presentation - [67]
Borland ML, Loveys K, Babl FE et al.. “Australasian Bronchiolitis Guideline: 2025 Update.” Journal of paediatrics and child health (2025). PMID: 40685806 ↗
L1GUIDELINECited in: Clinical Presentation, History and Evolution of Treatment - [68]
Dong J, Ouyang Y, Ni J et al.. “Development and internal validation of a clinical prediction model for septic shock in pediatric respiratory syncytial virus bronchiolitis based on routine blood biomarkers and concomitant fungal infection.” Frontiers in cellular and infection microbiology (2026). PMID: 42221582 ↗
L2TRIAL_NONRANDOMCited in: Clinical Presentation, Diagnosis & Workup, Severity Grading, Staging & Risk Stratification, Growth, Development & Nutrition Impact, Special Populations - [69]
McLaren SH, Camargo CA, Florin TA et al.. “Young infants with bronchiolitis at low risk of respiratory deterioration in an urban, academic emergency department: prospective cohort study protocol.” BMJ open (2025). PMID: 40858371 ↗
L5TRIAL_NONRANDOMCited in: Clinical Presentation, History and Evolution of Treatment, Growth, Development & Nutrition Impact - [70]
Essouri S, Baudin F, Chevret L et al.. “Variability of Care in Infants with Severe Bronchiolitis: Less-Invasive Respiratory Management Leads to Similar Outcomes.” The Journal of pediatrics (2017). PMID: 28602381 ↗
L2OTHERCited in: Clinical Presentation, Severity Grading, Staging & Risk Stratification, Complications - [71]
Rao S, Armistead I, Tyler A et al.. “Respiratory Syncytial Virus, Influenza, and Coronavirus Disease 2019 Hospitalizations in Children in Colorado During the 2021-2022 Respiratory Virus Season.” The Journal of pediatrics (2023). PMID: 37201680 ↗
L2OTHERCited in: Clinical Presentation, Diagnosis & Workup, Prevention, Screening & Surveillance - [72]
Schuh S, Lalani A, Allen U et al.. “Evaluation of the utility of radiography in acute bronchiolitis.” The Journal of pediatrics (2007). PMID: 17382126 ↗
L2OTHERCited in: Clinical Presentation - [73]
Heath A, Rios D, Vogel KI et al.. “A randomised controlled trial comparing epinephrine and dexamethasone to placebo in the treatment of infants with bronchiolitis (BIPED study): a statistical analysis plan.” Trials (2025). PMID: 41225556 ↗
L5RCTCited in: Clinical Presentation - [74]
Sharan RV, Rahimi-Ardabili H. “Detecting acute respiratory diseases in the pediatric population using cough sound features and machine learning: A systematic review.” International journal of medical informatics (2023). PMID: 37224643 ↗
L2SR_OBSCited in: Clinical Presentation - [75]
Thouvenin G, Abou Taam R, Flamein F et al.. “Characteristics of disorders associated with genetic mutations of surfactant protein C.” Archives of disease in childhood (2010). PMID: 20403820 ↗
L4OTHERCited in: Clinical Presentation, Growth, Development & Nutrition Impact - [76]
Murch H, Oakley J, Pierrepoint M et al.. “Using multifaceted education to improve management in acute viral bronchiolitis.” Archives of disease in childhood (2015). PMID: 25888695 ↗
L4OTHERCited in: Clinical Presentation, Diagnosis & Workup - [77]
Hartling L, Bialy LM, Vandermeer B et al.. “Epinephrine for bronchiolitis.” The Cochrane database of systematic reviews (2011). PMID: 21678340 ↗
L1SR_OBSCited in: Clinical Presentation - [78]
Umoren R, Odey F, Meremikwu MM. “Steam inhalation or humidified oxygen for acute bronchiolitis in children up to three years of age.” The Cochrane database of systematic reviews (2011). PMID: 21249676 ↗
L1SR_OBSCited in: Clinical Presentation - [79]
Diaz-Diaz A, Garcia-Maurino C, Jordan-Villegas A et al.. “Viral Bacterial Interactions in Children: Impact on Clinical Outcomes.” The Pediatric infectious disease journal (2019). PMID: 31205238 ↗
L5REVIEW_NARRATIVECited in: Clinical Presentation, Severity Grading, Staging & Risk Stratification, Complications, Prognosis & Natural History, Special Populations - [80]
Moro MR, Bonville CA, Suryadevara M et al.. “Clinical features, adenovirus types, and local production of inflammatory mediators in adenovirus infections.” The Pediatric infectious disease journal (2009). PMID: 19319023 ↗
L4OTHERCited in: Clinical Presentation - [81]
Nenna R, Pierangeli A, Matera L et al.. “Respiratory Syncytial Virus Bronchiolitis Before and After COVID-19 Pandemic: Has the Immunity Debt Been Paid Off?” The Pediatric infectious disease journal (2024). PMID: 38451927 ↗
L2OTHERCited in: Clinical Presentation, Severity Grading, Staging & Risk Stratification, Prevention, Screening & Surveillance - [82]
Kadmon G, Feinstein Y, Lazar I et al.. “Variability of Care of Infants With Severe Respiratory Syncytial Virus Bronchiolitis: A Multicenter Study.” The Pediatric infectious disease journal (2020). PMID: 32304465 ↗
L4OTHERCited in: Clinical Presentation, Diagnosis & Workup - [83]
Ralston SL, Lieberthal AS, Meissner HC et al.. “Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis.” Pediatrics (2014). PMID: 25349312 ↗
L1GUIDELINECited in: Diagnosis & Workup, Long-term & Definitive Management, History and Evolution of Treatment - [84]
Wu S, Baker C, Lang ME et al.. “Nebulized hypertonic saline for bronchiolitis: a randomized clinical trial.” JAMA pediatrics (2014). PMID: 24862623 ↗
L1RCTCited in: Diagnosis & Workup, Long-term & Definitive Management, History and Evolution of Treatment - [85]
Mittal V, Hall M, Morse R et al.. “Impact of inpatient bronchiolitis clinical practice guideline implementation on testing and treatment.” The Journal of pediatrics (2014). PMID: 24961787 ↗
L2GUIDELINECited in: Diagnosis & Workup - [86]
Gelbart B, McSharry B, Delzoppo C et al.. “Pragmatic Randomized Trial of Corticosteroids and Inhaled Epinephrine for Bronchiolitis in Children in Intensive Care.” The Journal of pediatrics (2022). PMID: 35093318 ↗
L1RCTCited in: Diagnosis & Workup, Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [87]
Zorc JJ, Hall CB. “Bronchiolitis: recent evidence on diagnosis and management.” Pediatrics (2010). PMID: 20100768 ↗
L5REVIEW_NARRATIVECited in: Diagnosis & Workup, Prevention, Screening & Surveillance - [88]
Frazier SB, Walls C, Jain S et al.. “Reducing Chest Radiographs in Bronchiolitis Through High-Reliability Interventions.” Pediatrics (2021). PMID: 34344801 ↗
L4OTHERCited in: Diagnosis & Workup - [89]
Nakamura MM, Zaslavsky AM, Toomey SL et al.. “Pediatric Readmissions After Hospitalizations for Lower Respiratory Infections.” Pediatrics (2017). PMID: 28771405 ↗
L2OTHERCited in: Diagnosis & Workup - [90]
Farber HJ, Buckwold FJ, Lachman B et al.. “Observed Effectiveness of Palivizumab for 29-36-Week Gestation Infants.” Pediatrics (2016). PMID: 27432850 ↗
L2OTHERCited in: Diagnosis & Workup - [91]
Perramon-Malavez A, Hermosilla E, Coma E et al.. “Effectiveness of Nirsevimab Immunoprophylaxis Against Respiratory Syncytial Virus-related Outcomes in Hospital Care Settings: A Seasonal Cohort Study of Infants in Catalonia, Spain.” The Pediatric infectious disease journal (2025). PMID: 39823640 ↗
L2COHORTCited in: Diagnosis & Workup, Prognosis & Natural History, Prevention, Screening & Surveillance - [92]
Mahant S, Parkin PC, Thavam T et al.. “Rates in Bronchiolitis Hospitalization, Intensive Care Unit Use, Mortality, and Costs From 2004 to 2018.” JAMA pediatrics (2022). PMID: 34928313 ↗
L2OTHERCited in: Diagnosis & Workup, Prognosis & Natural History - [93]
Beck AF, Florin TA, Campanella S et al.. “Geographic Variation in Hospitalization for Lower Respiratory Tract Infections Across One County.” JAMA pediatrics (2015). PMID: 26192102 ↗
L2OTHERCited in: Diagnosis & Workup, Special Populations - [94]
Principi T, Coates AL, Parkin PC et al.. “Effect of Oxygen Desaturations on Subsequent Medical Visits in Infants Discharged From the Emergency Department With Bronchiolitis.” JAMA pediatrics (2016). PMID: 26928704 ↗
L2OTHERCited in: Diagnosis & Workup, Prognosis & Natural History, Special Populations - [95]
Elliott SA, Cyrkot S, Scott SD et al.. “Enhancing parental health knowledge through digital knowledge mobilisation tools: a randomised controlled trial and qualitative study.” BMJ paediatrics open (2026). PMID: 42173560 ↗
L1RCTCited in: Diagnosis & Workup, Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [96]
Assad Z, Romain AS, Aupiais C et al.. “Nirsevimab and Hospitalization for RSV Bronchiolitis.” The New England journal of medicine (2024). PMID: 38986058 ↗
L3OTHERCited in: Diagnosis & Workup - [97]
Marin JR, Hollander MAG, Ray KN et al.. “Low-Value Diagnostic Imaging in Children with Medicaid.” The Journal of pediatrics (2021). PMID: 33556364 ↗
L2OTHERCited in: Diagnosis & Workup, Special Populations - [98]
Bucholz EM, Gay JC, Hall M et al.. “Timing and Causes of Common Pediatric Readmissions.” The Journal of pediatrics (2018). PMID: 29887387 ↗
L2OTHERCited in: Diagnosis & Workup - [99]
Rolfsjord LB, Bakkeheim E, Berents TL et al.. “Morning Salivary Cortisol in Young Children: Reference Values and the Effects of Age, Sex, and Acute Bronchiolitis.” The Journal of pediatrics (2017). PMID: 28284475 ↗
L2OTHERCited in: Diagnosis & Workup - [100]
Hartmann F, Fiori HH, Ramos Garcia PC et al.. “Surfactant deficiency in infants with severe acute viral bronchiolitis.” The Journal of pediatrics (2014). PMID: 24657121 ↗
L3OTHERCited in: Diagnosis & Workup - [101]
Loveys K, Borland ML, Oakley E et al.. “Investigations for Bronchiolitis in Infants: An Overview of Reviews and Systematic Review of Primary Studies.” Pediatric pulmonology (2026). PMID: 41906981 ↗
L2SR_OBSCited in: Diagnosis & Workup - [102]
Loveys K, Haskell L, Cotterell E et al.. “Efficacy and Safety of Azithromycin in Infants With Bronchiolitis: A Systematic Review and Meta-Analysis.” Acta paediatrica (Oslo, Norway : 1992) (2025). PMID: 41074495 ↗
L1SR_OBSCited in: Diagnosis & Workup - [103]
Bowyer SA, Bryant WA, Key D et al.. “Machine learning forecasting for COVID-19 pandemic-associated effects on paediatric respiratory infections.” Archives of disease in childhood (2022). PMID: 35948401 ↗
L3OTHERCited in: Diagnosis & Workup - [104]
Griffiths B, Riphagen S, Lillie J. “Management of severe bronchiolitis: impact of NICE guidelines.” Archives of disease in childhood (2018). PMID: 30472669 ↗
L4OTHERCited in: Diagnosis & Workup - [105]
Cathie K, Sutcliffe AG, Bandi S et al.. “Priorities for child health research across the UK and Ireland.” Archives of disease in childhood (2021). PMID: 34716174 ↗
L5OTHERCited in: Diagnosis & Workup, Special Populations - [106]
Fitzpatrick T, McNally JD, Stukel TA et al.. “Palivizumab's real-world effectiveness: a population-based study in Ontario, Canada, 1993-2017.” Archives of disease in childhood (2020). PMID: 32859612 ↗
L2OTHERCited in: Diagnosis & Workup - [107]
van Hasselt TJ, Singham B, Bassett E et al.. “Oxygen saturation thresholds in bronchiolitis: examining admissions.” Archives of disease in childhood (2019). PMID: 31462433 ↗
L2OTHERCited in: Diagnosis & Workup - [108]
Marlais M, Evans J, Abrahamson E. “Clinical predictors of admission in infants with acute bronchiolitis.” Archives of disease in childhood (2011). PMID: 21339199 ↗
L2OTHERCited in: Diagnosis & Workup, Complications - [109]
Manti S, Gambadauro A, Stocchero M et al.. “Application of machine learning to predict bronchiolitis severity in children: a single-centre retrospective cohort study.” European journal of pediatrics (2026). PMID: 42171780 ↗
L3COHORTCited in: Diagnosis & Workup - [110]
Shanklin A, Rivera EAT, Pollack MM et al.. “The Association of Iatrogenic Withdrawal With Opioid and Benzodiazepine Weaning in Children With Bronchiolitis: A Single-Center, Retrospective Cohort Study, 2012-2022.” Critical care explorations (2026). PMID: 41823985 ↗
L3COHORTCited in: Diagnosis & Workup, Prognosis & Natural History - [111]
Spurling GK, Fonseka K, Doust J et al.. “Antibiotics for bronchiolitis in children.” The Cochrane database of systematic reviews (2007). PMID: 17253545 ↗
L1SR_OBSCited in: Diagnosis & Workup, Complications - [112]
Beggs S, Wong ZH, Kaul S et al.. “High-flow nasal cannula therapy for infants with bronchiolitis.” The Cochrane database of systematic reviews (2014). PMID: 24442856 ↗
L1SR_OBSCited in: Diagnosis & Workup, Complications - [113]
Gill PJ, Anwar MR, Kornelsen E et al.. “Parenteral versus enteral fluid therapy for children hospitalised with bronchiolitis.” The Cochrane database of systematic reviews (2021). PMID: 34852398 ↗
L1SR_OBSCited in: Diagnosis & Workup, Complications, Prognosis & Natural History, Special Populations - [114]
McCallum GB, Plumb EJ, Morris PS et al.. “Antibiotics for persistent cough or wheeze following acute bronchiolitis in children.” The Cochrane database of systematic reviews (2017). PMID: 28828759 ↗
L1SR_OBSCited in: Diagnosis & Workup - [115]
Mayfield S, Jauncey-Cooke J, Hough JL et al.. “High-flow nasal cannula therapy for respiratory support in children.” The Cochrane database of systematic reviews (2014). PMID: 24604698 ↗
L1SR_OBSCited in: Diagnosis & Workup - [116]
Blom D, Ermers M, Bont L et al.. “Inhaled corticosteroids during acute bronchiolitis in the prevention of post-bronchiolitic wheezing.” The Cochrane database of systematic reviews (2007). PMID: 17253528 ↗
L1SR_OBSCited in: Diagnosis & Workup - [117]
Blom DJ, Ermers M, Bont L et al.. “WITHDRAWN: Inhaled corticosteroids during acute bronchiolitis in the prevention of post-bronchiolitic wheezing.” The Cochrane database of systematic reviews (2011). PMID: 21249665 ↗
L1SR_OBSCited in: Diagnosis & Workup, History and Evolution of Treatment - [118]
Falsey AR. “Human metapneumovirus infection in adults.” The Pediatric infectious disease journal (2008). PMID: 18820584 ↗
L5OTHERCited in: Diagnosis & Workup, Complications, Prognosis & Natural History, Special Populations - [119]
Zaharov T, Franck KT, Nygaard U et al.. “Chronic Lung Disease after Hospitalization with Adenovirus or Respiratory Syncytial Virus.” The Pediatric infectious disease journal (2025). PMID: 40215198 ↗
L3OTHERCited in: Diagnosis & Workup - [120]
Sippy R, Prado EO, Pizarro Fajardo F et al.. “Medically Attended Outpatient Coronavirus Infections in Ecuadorean Children During the 20 Months Preceding Countrywide Lockdown Related to the SARS-CoV-2 Pandemic of 2020.” The Pediatric infectious disease journal (2020). PMID: 32773657 ↗
L2OTHERCited in: Diagnosis & Workup - [121]
Calvo C, García-García ML, Pozo F et al.. “Clinical characteristics of human bocavirus infections compared with other respiratory viruses in Spanish children.” The Pediatric infectious disease journal (2008). PMID: 18574440 ↗
L2OTHERCited in: Diagnosis & Workup - [122]
Kooiman L, Blankespoor F, Hofman R et al.. “High-flow oxygen therapy in moderate to severe bronchiolitis: a randomised controlled trial.” Archives of disease in childhood (2023). PMID: 36941030 ↗
L1RCTCited in: Severity Grading, Staging & Risk Stratification, Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [123]
Schondelmeyer AC, Dewan ML, Brady PW et al.. “Cardiorespiratory and Pulse Oximetry Monitoring in Hospitalized Children: A Delphi Process.” Pediatrics (2020). PMID: 32680879 ↗
L5REVIEW_NARRATIVECited in: Severity Grading, Staging & Risk Stratification - [124]
Fernandes RM, Plint AC, Terwee CB et al.. “Validity of bronchiolitis outcome measures.” Pediatrics (2015). PMID: 25986025 ↗
L4OTHERCited in: Severity Grading, Staging & Risk Stratification, Prognosis & Natural History, Special Populations - [125]
Hinderstein S, Aragona E, Loyal J. “Parent Perspectives on Nirsevimab for Their Newborn.” Pediatrics (2024). PMID: 39587878 ↗
L5OTHERCited in: Severity Grading, Staging & Risk Stratification, Prevention, Screening & Surveillance - [126]
Synhorst DC, Johnson MB, Bettenhausen JL et al.. “Room Costs for Common Pediatric Hospitalizations and Cost-Reducing Quality Initiatives.” Pediatrics (2020). PMID: 32366609 ↗
L2OTHERCited in: Severity Grading, Staging & Risk Stratification - [127]
Bourgeois FT, Monuteaux MC, Stack AM et al.. “Variation in emergency department admission rates in US children's hospitals.” Pediatrics (2014). PMID: 25113291 ↗
L2OTHERCited in: Severity Grading, Staging & Risk Stratification - [128]
Fieldston ES, Shah SS, Hall M et al.. “Resource utilization for observation-status stays at children's hospitals.” Pediatrics (2013). PMID: 23669520 ↗
L2OTHERCited in: Severity Grading, Staging & Risk Stratification - [129]
Heneghan JA, Goodman DM, Ramgopal S. “Hospitalizations at United States Children's Hospitals and Severity of Illness by Neighborhood Child Opportunity Index.” The Journal of pediatrics (2022). PMID: 36270394 ↗
L2OTHERCited in: Severity Grading, Staging & Risk Stratification, Complications - [130]
Vo P, Koppel C, Espinola JA et al.. “Vitamin D Status at the Time of Hospitalization for Bronchiolitis and Its Association with Disease Severity.” The Journal of pediatrics (2018). PMID: 30243543 ↗
L2OTHERCited in: Severity Grading, Staging & Risk Stratification - [131]
Milési C, Requirand A, Douillard A et al.. “Assessment of Peak Inspiratory Flow in Young Infants with Acute Viral Bronchiolitis: Physiological Basis for Initial Flow Setting in Patients Supported with High-Flow Nasal Cannula.” The Journal of pediatrics (2020). PMID: 33333115 ↗
L4OTHERCited in: Severity Grading, Staging & Risk Stratification - [132]
Gordon B, Nyiro JU, Nair H et al.. “External Validation of Pediatric Pneumonia and Bronchiolitis Risk Scores to Predict Mortality in Children Hospitalized in Kenya: A Retrospective Cohort Study.” The Journal of infectious diseases (2026). PMID: 40692486 ↗
L2COHORTCited in: Severity Grading, Staging & Risk Stratification, Prognosis & Natural History - [133]
Moraa I, Sturman N, McGuire T et al.. “Heliox for croup in children.” The Cochrane database of systematic reviews (2013). PMID: 24318607 ↗
L1SR_OBSCited in: Severity Grading, Staging & Risk Stratification - [134]
Ozeki S, Oshiro M, Fukumi D et al.. “Change Over Time in Seasonality and Severity of Children Hospitalized With Respiratory Syncytial Virus Infection in Japan.” The Pediatric infectious disease journal (2022). PMID: 35544732 ↗
L4OTHERCited in: Severity Grading, Staging & Risk Stratification - [135]
McClintock J, Odom-Mabey AR, Kebere N et al.. “Postmortem Nasopharyngeal Microbiome Analysis of Zambian Infants With and Without Respiratory Syncytial Virus Disease: A Nested Case Control Study.” The Pediatric infectious disease journal (2023). PMID: 37093853 ↗
L3OTHERCited in: Severity Grading, Staging & Risk Stratification, Prognosis & Natural History - [136]
Erkkola R, Turunen R, Räisänen K et al.. “Rhinovirus C Is Associated With Severe Wheezing and Febrile Respiratory Illness in Young Children.” The Pediatric infectious disease journal (2020). PMID: 31876616 ↗
L2OTHERCited in: Severity Grading, Staging & Risk Stratification, History and Evolution of Treatment - [137]
Abu Raya B, Bamberger E, Kassis I et al.. “Bordetella pertussis infection attenuates clinical course of acute bronchiolitis.” The Pediatric infectious disease journal (2013). PMID: 23429556 ↗
L3OTHERCited in: Severity Grading, Staging & Risk Stratification - [138]
Guerrero-Del-Cueto F, Lobato-Lopez S, Lozano-Duran D et al.. “Assessing the Impact of Nirsevimab Immunization on RSV Bronchiolitis Hospital Admissions and Their Severity: A Case-Control Study and Comparison With Pre- and Post-COVID-19 Seasons in a Tertiary Pediatric Hospital.” Pediatric pulmonology (2025). PMID: 40662491 ↗
L3CASE_CONTROLCited in: Severity Grading, Staging & Risk Stratification - [139]
Hermoso PS, Conejo MM, Alejandre C et al.. “Long-Term Functional Outcomes After Pediatric Intensive Care Unit Admission for Bronchiolitis: A 12-Month Cohort Study.” Children (Basel, Switzerland) (2026). PMID: 42194162 ↗
L2COHORTCited in: Severity Grading, Staging & Risk Stratification - [140]
Oweidat M, Alra'e M, Allawi R et al.. “Association of high-flow nasal cannula (HFNC) therapy with intensive care unit admission and mechanical ventilation use in respiratory syncytial virus-positive bronchiolitis in pediatric patients: a retrospective single-center cohort study.” BMC pulmonary medicine (2026). PMID: 41987094 ↗
L2COHORTCited in: Severity Grading, Staging & Risk Stratification - [141]
Ito M, Nakano A, Arimoto Y et al.. “Clinical characteristics and severity of primary ciliary dyskinesia caused by large homozygous deletion including exons 1-4 of DRC1: A multicenter retrospective cohort study.” Respiratory investigation (2026). PMID: 41570615 ↗
L2COHORTCited in: Severity Grading, Staging & Risk Stratification - [142]
Roqué-Figuls M, Giné-Garriga M, Granados Rugeles C et al.. “Chest physiotherapy for acute bronchiolitis in paediatric patients between 0 and 24 months old.” The Cochrane database of systematic reviews (2023). PMID: 37010196 ↗
L1REVIEW_NARRATIVECited in: Severity Grading, Staging & Risk Stratification - [143]
Silver AH, Esteban-Cruciani N, Azzarone G et al.. “3% Hypertonic Saline Versus Normal Saline in Inpatient Bronchiolitis: A Randomized Controlled Trial.” Pediatrics (2015). PMID: 26553190 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment - [144]
Alansari K, Toaimah FH, Almatar DH et al.. “Monoclonal Antibody Treatment of RSV Bronchiolitis in Young Infants: A Randomized Trial.” Pediatrics (2019). PMID: 30760509 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History - [145]
Chidini G, Piastra M, Marchesi T et al.. “Continuous positive airway pressure with helmet versus mask in infants with bronchiolitis: an RCT.” Pediatrics (2015). PMID: 25780074 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, Complications - [146]
Haskell L, Tavender EJ, Wilson CL et al.. “Effectiveness of Targeted Interventions on Treatment of Infants With Bronchiolitis: A Randomized Clinical Trial.” JAMA pediatrics (2021). PMID: 33843971 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Growth, Development & Nutrition Impact, Prognosis & Natural History, Special Populations - [147]
Angoulvant F, Bellêttre X, Milcent K et al.. “Effect of Nebulized Hypertonic Saline Treatment in Emergency Departments on the Hospitalization Rate for Acute Bronchiolitis: A Randomized Clinical Trial.” JAMA pediatrics (2017). PMID: 28586918 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Special Populations - [148]
Florin TA, Shaw KN, Kittick M et al.. “Nebulized hypertonic saline for bronchiolitis in the emergency department: a randomized clinical trial.” JAMA pediatrics (2014). PMID: 24862342 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [149]
Plint AC, Johnson DW, Patel H et al.. “Epinephrine and dexamethasone in children with bronchiolitis.” The New England journal of medicine (2009). PMID: 19439742 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [150]
Kepreotes E, Whitehead B, Attia J et al.. “High-flow warm humidified oxygen versus standard low-flow nasal cannula oxygen for moderate bronchiolitis (HFWHO RCT): an open, phase 4, randomised controlled trial.” Lancet (London, England) (2017). PMID: 28161016 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [151]
Alansari K, Toaimah FH, Khalafalla H et al.. “Caffeine for the Treatment of Apnea in Bronchiolitis: A Randomized Trial.” The Journal of pediatrics (2016). PMID: 27189681 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [152]
Kuzik BA, Al-Qadhi SA, Kent S et al.. “Nebulized hypertonic saline in the treatment of viral bronchiolitis in infants.” The Journal of pediatrics (2007). PMID: 17719935 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, Prognosis & Natural History - [153]
Tie SW, Hall GL, Peter S et al.. “Home oxygen for children with acute bronchiolitis.” Archives of disease in childhood (2008). PMID: 18927148 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, Complications, Special Populations - [154]
Zomer-Kooijker K, van der Ent CK, Ermers MJ et al.. “Lack of long-term effects of high-dose inhaled beclomethasone for respiratory syncytial virus bronchiolitis: a randomized placebo-controlled trial.” The Pediatric infectious disease journal (2014). PMID: 24346594 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management, History and Evolution of Treatment, Growth, Development & Nutrition Impact, Prognosis & Natural History - [155]
Backman K, Helminen M, Kekäläinen E et al.. “Working group summary of the 2023 full update of the Finnish national guidelines for paediatric lower respiratory tract infections.” Acta paediatrica (Oslo, Norway : 1992) (2024). PMID: 39487609 ↗
L1GUIDELINECited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management - [156]
Riese J, Porter T, Fierce J et al.. “Clinical Outcomes of Bronchiolitis After Implementation of a General Ward High Flow Nasal Cannula Guideline.” Hospital pediatrics (2017). PMID: 28292850 ↗
L2GUIDELINECited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [157]
Tapiainen T, Aittoniemi J, Immonen J et al.. “Finnish guidelines for the treatment of laryngitis, wheezing bronchitis and bronchiolitis in children.” Acta paediatrica (Oslo, Norway : 1992) (2015). PMID: 26295564 ↗
L1GUIDELINECited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [158]
Maya M, Rameshkumar R, Selvan T et al.. “High-Flow Nasal Cannula Versus Nasal Prong Bubble Continuous Positive Airway Pressure in Children With Moderate to Severe Acute Bronchiolitis: A Randomized Controlled Trial.” Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies (2024). PMID: 38639564 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization, Long-term & Definitive Management - [159]
Schuh S, Coates AL, Sweeney J et al.. “Nasal Suctioning Therapy Among Infants With Bronchiolitis Discharged Home From the Emergency Department: A Randomized Clinical Trial.” JAMA network open (2023). PMID: 37856126 ↗
L1RCTCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [160]
Alansari K, Sakran M, Davidson BL et al.. “Oral dexamethasone for bronchiolitis: a randomized trial.” Pediatrics (2013). PMID: 24043283 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [161]
Jacobs JD, Foster M, Wan J et al.. “7% Hypertonic saline in acute bronchiolitis: a randomized controlled trial.” Pediatrics (2013). PMID: 24344111 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [162]
Chowdhury MM, McKenzie SA, Pearson CC et al.. “Heliox therapy in bronchiolitis: phase III multicenter double-blind randomized controlled trial.” Pediatrics (2013). PMID: 23509160 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [163]
Bajaj L, Turner CG, Bothner J. “A randomized trial of home oxygen therapy from the emergency department for acute bronchiolitis.” Pediatrics (2006). PMID: 16510641 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment, Complications - [164]
Elliott SA, Gaudet LA, Fernandes RM et al.. “Comparative Efficacy of Bronchiolitis Interventions in Acute Care: A Network Meta-analysis.” Pediatrics (2021). PMID: 33893229 ↗
L1SR_OBSCited in: Long-term & Definitive Management, Special Populations - [165]
McCulloh R, Koster M, Ralston S et al.. “Use of Intermittent vs Continuous Pulse Oximetry for Nonhypoxemic Infants and Young Children Hospitalized for Bronchiolitis: A Randomized Clinical Trial.” JAMA pediatrics (2015). PMID: 26322819 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [166]
Franklin D, Babl FE, Schlapbach LJ et al.. “A Randomized Trial of High-Flow Oxygen Therapy in Infants with Bronchiolitis.” The New England journal of medicine (2018). PMID: 29562151 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [167]
Skjerven HO, Hunderi JO, Brügmann-Pieper SK et al.. “Racemic adrenaline and inhalation strategies in acute bronchiolitis.” The New England journal of medicine (2013). PMID: 23758233 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [168]
Cunningham S, Rodriguez A, Adams T et al.. “Oxygen saturation targets in infants with bronchiolitis (BIDS): a double-blind, randomised, equivalence trial.” Lancet (London, England) (2015). PMID: 26382998 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [169]
Al-Ansari K, Sakran M, Davidson BL et al.. “Nebulized 5% or 3% hypertonic or 0.9% saline for treating acute bronchiolitis in infants.” The Journal of pediatrics (2010). PMID: 20646715 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [170]
Ralston S, Roohi M. “A randomized, controlled trial of nasal phenylephrine in infants hospitalized for bronchiolitis.” The Journal of pediatrics (2008). PMID: 18657831 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [171]
Kim CK, Choi J, Kim HB et al.. “A randomized intervention of montelukast for post-bronchiolitis: effect on eosinophil degranulation.” The Journal of pediatrics (2010). PMID: 20171653 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [172]
Pinto LA, Pitrez PM, Luisi F et al.. “Azithromycin therapy in hospitalized infants with acute bronchiolitis is not associated with better clinical outcomes: a randomized, double-blinded, and placebo-controlled clinical trial.” The Journal of pediatrics (2012). PMID: 22748516 ↗
L1RCTCited in: Long-term & Definitive Management - [173]
Valencia-Ramos J, Ochoa Sangrador C, García M et al.. “Impact of different nebulisation systems on patient comfort in bronchiolitis: a randomised controlled cross-over trial.” Archives of disease in childhood (2022). PMID: 36162958 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment, Prognosis & Natural History - [174]
Bueno Campaña M, Olivares Ortiz J, Notario Muñoz C et al.. “High flow therapy versus hypertonic saline in bronchiolitis: randomised controlled trial.” Archives of disease in childhood (2014). PMID: 24521787 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [175]
Thia LP, McKenzie SA, Blyth TP et al.. “Randomised controlled trial of nasal continuous positive airways pressure (CPAP) in bronchiolitis.” Archives of disease in childhood (2007). PMID: 17344251 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment, Complications - [176]
Lin J, Zhang Y, Xiong L et al.. “High-flow nasal cannula therapy for children with bronchiolitis: a systematic review and meta-analysis.” Archives of disease in childhood (2019). PMID: 30655267 ↗
L1SR_OBSCited in: Long-term & Definitive Management - [177]
Livni G, Rachmel A, Marom D et al.. “A randomized, double-blind study examining the comparative efficacies and safety of inhaled epinephrine and nasal decongestant in hospitalized infants with acute bronchiolitis.” The Pediatric infectious disease journal (2010). PMID: 19907355 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment - [178]
Semple MG, Donohue C, Price L et al.. “Endotracheal surfactant for infants with life-threatening bronchiolitis (BESS): a randomised, blinded, sham-controlled, phase 2 trial.” The Lancet. Respiratory medicine (2026). PMID: 41875912 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment, Growth, Development & Nutrition Impact - [179]
Kaushik M, Bhalla K. “Comparison of 3 different flow rates of high-flow nasal cannula (1 L/kg/min versus 2 L/kg/min versus 3 L/kg/min) in management of children admitted with bronchiolitis: a randomized controlled trial.” European journal of pediatrics (2025). PMID: 41430493 ↗
L1RCTCited in: Long-term & Definitive Management, History and Evolution of Treatment, Complications - [180]
Kulkarni PS, Zaman K, Desai SA et al.. “Safety and immunogenicity of a reduced-dose inactivated poliovirus vaccine versus a full-dose inactivated poliovirus vaccine in infants in Bangladesh: a double-blind, non-inferiority, randomised, controlled, phase 3 trial.” The Lancet. Infectious diseases (2025). PMID: 40505670 ↗
L1RCTCited in: Long-term & Definitive Management - [181]
Combret Y, Machefert M, Couet M et al.. “Effect of a prolonged slow expiration technique on 24-h food intake in children hospitalized for moderate bronchiolitis: a randomized controlled trial.” Italian journal of pediatrics (2024). PMID: 39334411 ↗
L1RCTCited in: Long-term & Definitive Management - [182]
Gadomski AM, Scribani MB. “Bronchodilators for bronchiolitis.” The Cochrane database of systematic reviews (2014). PMID: 24937099 ↗
L1SR_OBSCited in: Long-term & Definitive Management - [183]
Jat KR, Chawla D. “Surfactant therapy for bronchiolitis in critically ill infants.” The Cochrane database of systematic reviews (2015). PMID: 26299681 ↗
L1SR_OBSCited in: Long-term & Definitive Management, Complications, Prognosis & Natural History, Special Populations - [184]
Gadomski AM, Brower M. “Bronchodilators for bronchiolitis.” The Cochrane database of systematic reviews (2010). PMID: 21154348 ↗
L1SR_OBSCited in: Long-term & Definitive Management - [185]
Fernandes RM, Bialy LM, Vandermeer B et al.. “Glucocorticoids for acute viral bronchiolitis in infants and young children.” The Cochrane database of systematic reviews (2013). PMID: 23733383 ↗
L1SR_OBSCited in: Long-term & Definitive Management - [186]
Jat KR, Mathew JL. “Continuous positive airway pressure (CPAP) for acute bronchiolitis in children.” The Cochrane database of systematic reviews (2019). PMID: 30701528 ↗
L1SR_OBSCited in: Long-term & Definitive Management - [187]
Liet JM, Ducruet T, Gupta V et al.. “Heliox inhalation therapy for bronchiolitis in infants.” The Cochrane database of systematic reviews (2010). PMID: 20393951 ↗
L1SR_OBSCited in: Long-term & Definitive Management - [188]
Liet JM, Ducruet T, Gupta V et al.. “Heliox inhalation therapy for bronchiolitis in infants.” The Cochrane database of systematic reviews (2015). PMID: 26384333 ↗
L1SR_OBSCited in: Long-term & Definitive Management - [189]
Jat KR, Chawla D. “Surfactant therapy for bronchiolitis in critically ill infants.” The Cochrane database of systematic reviews (2012). PMID: 22972138 ↗
L1SR_OBSCited in: Long-term & Definitive Management, Prognosis & Natural History, Special Populations - [190]
Hogeling M, Adams S, Wargon O. “A randomized controlled trial of propranolol for infantile hemangiomas.” Pediatrics (2011). PMID: 21788220 ↗
L1RCTCited in: History and Evolution of Treatment, Growth, Development & Nutrition Impact - [191]
Amirav I, Luder AS, Kruger N et al.. “A double-blind, placebo-controlled, randomized trial of montelukast for acute bronchiolitis.” Pediatrics (2008). PMID: 18984650 ↗
L1RCTCited in: History and Evolution of Treatment - [192]
Mallory MD, Shay DK, Garrett J et al.. “Bronchiolitis management preferences and the influence of pulse oximetry and respiratory rate on the decision to admit.” Pediatrics (2003). PMID: 12509594 ↗
L5RCTCited in: History and Evolution of Treatment - [193]
Mahant S, Wahi G, Bayliss A et al.. “Intermittent vs Continuous Pulse Oximetry in Hospitalized Infants With Stabilized Bronchiolitis: A Randomized Clinical Trial.” JAMA pediatrics (2021). PMID: 33646286 ↗
L1RCTCited in: History and Evolution of Treatment - [194]
Coon ER, Destino LA, Greene TH et al.. “Comparison of As-Needed and Scheduled Posthospitalization Follow-up for Children Hospitalized for Bronchiolitis: The Bronchiolitis Follow-up Intervention Trial (BeneFIT) Randomized Clinical Trial.” JAMA pediatrics (2020). PMID: 32628250 ↗
L1RCTCited in: History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [195]
Corneli HM, Zorc JJ, Mahajan P et al.. “A multicenter, randomized, controlled trial of dexamethasone for bronchiolitis.” The New England journal of medicine (2007). PMID: 17652648 ↗
L1RCTCited in: History and Evolution of Treatment - [196]
Wainwright C, Altamirano L, Cheney M et al.. “A multicenter, randomized, double-blind, controlled trial of nebulized epinephrine in infants with acute bronchiolitis.” The New England journal of medicine (2003). PMID: 12840089 ↗
L1RCTCited in: History and Evolution of Treatment - [197]
Roosevelt G, Sheehan K, Grupp-Phelan J et al.. “Dexamethasone in bronchiolitis: a randomised controlled trial.” Lancet (London, England) (1996). PMID: 8709687 ↗
L1RCTCited in: History and Evolution of Treatment - [198]
Swingler GH, Hussey GD, Zwarenstein M. “Randomised controlled trial of clinical outcome after chest radiograph in ambulatory acute lower-respiratory infection in children.” Lancet (London, England) (1998). PMID: 9482294 ↗
L1RCTCited in: History and Evolution of Treatment - [199]
Schuh S, Canny G, Reisman JJ et al.. “Nebulized albuterol in acute bronchiolitis.” The Journal of pediatrics (1990). PMID: 2213394 ↗
L1RCTCited in: History and Evolution of Treatment - [200]
Klassen TP, Rowe PC, Sutcliffe T et al.. “Randomized trial of salbutamol in acute bronchiolitis.” The Journal of pediatrics (1991). PMID: 2019938 ↗
L1RCTCited in: History and Evolution of Treatment - [201]
Klassen TP, Sutcliffe T, Watters LK et al.. “Dexamethasone in salbutamol-treated inpatients with acute bronchiolitis: a randomized, controlled trial.” The Journal of pediatrics (1997). PMID: 9042119 ↗
L1RCTCited in: History and Evolution of Treatment - [202]
Patel H, Gouin S, Platt RW. “Randomized, double-blind, placebo-controlled trial of oral albuterol in infants with mild-to-moderate acute viral bronchiolitis.” The Journal of pediatrics (2003). PMID: 12756382 ↗
L1RCTCited in: History and Evolution of Treatment - [203]
Hemming VG, Prince GA, Rodriguez W et al.. “Respiratory syncytial virus infections and intravenous gamma-globulins.” The Pediatric infectious disease journal (1988). PMID: 3041354 ↗
L5RCTCited in: History and Evolution of Treatment - [204]
Fox GF, Everard ML, Marsh MJ et al.. “Randomised controlled trial of budesonide for the prevention of post-bronchiolitis wheezing.” Archives of disease in childhood (1999). PMID: 10086941 ↗
L1RCTCited in: History and Evolution of Treatment - [205]
Barry W, Cockburn F, Cornall R et al.. “Ribavirin aerosol for acute bronchiolitis.” Archives of disease in childhood (1986). PMID: 3524473 ↗
L1RCTCited in: History and Evolution of Treatment - [206]
Webb MS, Martin JA, Cartlidge PH et al.. “Chest physiotherapy in acute bronchiolitis.” Archives of disease in childhood (1985). PMID: 3907510 ↗
L2RCTCited in: History and Evolution of Treatment - [207]
Cade A, Brownlee KG, Conway SP et al.. “Randomised placebo controlled trial of nebulised corticosteroids in acute respiratory syncytial viral bronchiolitis.” Archives of disease in childhood (2000). PMID: 10648365 ↗
L1RCTCited in: History and Evolution of Treatment - [208]
Menendez C, Sunyer J, Ventura PJ et al.. “Malaria infection does not appear to modify the risk of bronchiolitis early in life.” The Pediatric infectious disease journal (2002). PMID: 12005090 ↗
L2RCTCited in: History and Evolution of Treatment - [209]
Chipps BE, Sullivan WF, Portnoy JM. “Alpha-2A-interferon for treatment of bronchiolitis caused by respiratory syncytial virus.” The Pediatric infectious disease journal (1993). PMID: 8414778 ↗
L1RCTCited in: History and Evolution of Treatment - [210]
Tsai XC, Yao ZH, Chou SW et al.. “Taiwan consensus on pulmonary chronic graft-versus-host disease: A joint statement from the Taiwan Society of Blood and Marrow Transplantation (TBMT) and Taiwan Society of Pulmonary and Critical Care Medicine (TSPCCM).” British journal of haematology (2025). PMID: 40926299 ↗
L1GUIDELINECited in: History and Evolution of Treatment - [211]
Kattan M. “Epidemiologic evidence of increased airway reactivity in children with a history of bronchiolitis.” The Journal of pediatrics (1999). PMID: 10431133 ↗
L5REVIEW_NARRATIVECited in: History and Evolution of Treatment - [212]
Nagakumar P, Doull I. “Current therapy for bronchiolitis.” Archives of disease in childhood (2012). PMID: 22734014 ↗
L5REVIEW_NARRATIVECited in: History and Evolution of Treatment - [213]
Fuller HL, Del Mar CB. “WITHDRAWN: Immunoglobulin treatment for respiratory syncytial virus infection.” The Cochrane database of systematic reviews (2010). PMID: 20824840 ↗
L1SR_OBSCited in: History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [214]
Ventre K, Haroon M, Davison C. “WITHDRAWN. Surfactant therapy for bronchiolitis in critically ill infants.” The Cochrane database of systematic reviews (2010). PMID: 20091572 ↗
L1SR_OBSCited in: History and Evolution of Treatment, Special Populations - [215]
Patel H, Platt R, Lozano JM. “WITHDRAWN: Glucocorticoids for acute viral bronchiolitis in infants and young children.” The Cochrane database of systematic reviews (2008). PMID: 18254063 ↗
L1SR_OBSCited in: History and Evolution of Treatment - [216]
Soto-Martínez ME, Acuña Cordero R, Parra-Buitrago A et al.. “Respiratory Syncytial Virus in Pediatrics: Update on Epidemiology, Management, Long-term Consequences and Prevention. Consensus From Asociación Latinoamericana de Tórax (ALAT) 2025.” Archivos de bronconeumologia (2026). PMID: 41714249 ↗
L1GUIDELINECited in: History and Evolution of Treatment - [217]
Cravéreau O, Bourbonne V, Vaugier L et al.. “[Recommendations on the prevention and management of radiation-induced lung injury from the Association francophone pour les soins oncologiques de support and the Société française de radiothérapie oncologique].” Cancer radiotherapie : journal de la Societe francaise de radiotherapie oncologique (2025). PMID: 40774102 ↗
L1GUIDELINECited in: History and Evolution of Treatment - [218]
Perch M, Corris P, Lordan J et al.. “A European multicentre, randomised controlled trial of pirfenidone in bronchiolitis obliterans syndrome after bilateral lung transplantation.” The European respiratory journal (2026). PMID: 41232942 ↗
L1RCTCited in: History and Evolution of Treatment - [219]
Darras BT, Masson R, Mazurkiewicz-Bełdzińska M et al.. “Risdiplam-Treated Infants with Type 1 Spinal Muscular Atrophy versus Historical Controls.” The New England journal of medicine (2021). PMID: 34320287 ↗
L4OTHERCited in: History and Evolution of Treatment - [220]
King MS, Eisenberg R, Newman JH et al.. “Constrictive bronchiolitis in soldiers returning from Iraq and Afghanistan.” The New England journal of medicine (2011). PMID: 21774710 ↗
L4OTHERCited in: History and Evolution of Treatment - [221]
Dakhama A, Lee YM, Gelfand EW. “Virus-induced airway dysfunction: pathogenesis and biomechanisms.” The Pediatric infectious disease journal (2005). PMID: 16378041 ↗
L5REVIEW_NARRATIVECited in: History and Evolution of Treatment - [222]
Welliver RC. “Respiratory syncytial virus and other respiratory viruses.” The Pediatric infectious disease journal (2003). PMID: 12671447 ↗
L5REVIEW_NARRATIVECited in: History and Evolution of Treatment - [223]
Xanthouli P, Schatz A, Bergner R et al.. “[Management of pulmonary and cardiovascular comorbidities in rheumatological diseases].” Zeitschrift fur Rheumatologie (2025). PMID: 40736566 ↗
L1GUIDELINECited in: History and Evolution of Treatment - [224]
Bebia Z, Dieussaert I, Jose L et al.. “Randomized, placebo-controlled phase 3 trial evaluating safety, immunogenicity, and reactogenicity of RSVPreF3-Mat in high-risk pregnant women and their infants.” Human vaccines & immunotherapeutics (2026). PMID: 41766205 ↗
L1RCTCited in: History and Evolution of Treatment, Complications, Prevention, Screening & Surveillance - [225]
Harris J, Crulli B, Latour JM et al.. “Effect of Morphine on Respiratory Drive in Infants With Acute Viral Bronchiolitis Receiving Neurally Adjusted Ventilatory Assist.” Respiratory care (2025). PMID: 41626651 ↗
L1RCTCited in: History and Evolution of Treatment - [226]
Cozzi G, Sovtic A, Garelli D et al.. “SARS-CoV-2-related bronchiolitis: a multicentre international study.” Archives of disease in childhood (2023). PMID: 37130726 ↗
L3OTHERCited in: History and Evolution of Treatment, Prognosis & Natural History, Special Populations - [227]
Jartti T, Aakula M, Mansbach JM et al.. “Hospital length-of-stay is associated with rhinovirus etiology of bronchiolitis.” The Pediatric infectious disease journal (2014). PMID: 25222302 ↗
L2OTHERCited in: History and Evolution of Treatment - [228]
Grimaldi M, Gouyon B, Michaut F et al.. “Severe respiratory syncytial virus bronchiolitis: epidemiologic variations associated with the initiation of palivizumab in severely premature infants with bronchopulmonary dysplasia.” The Pediatric infectious disease journal (2004). PMID: 15626942 ↗
L2OTHERCited in: History and Evolution of Treatment - [229]
de Betue CT, van Waardenburg DA, Deutz NE et al.. “Increased protein-energy intake promotes anabolism in critically ill infants with viral bronchiolitis: a double-blind randomised controlled trial.” Archives of disease in childhood (2011). PMID: 21673183 ↗
L1RCTCited in: Growth, Development & Nutrition Impact - [230]
Arias AV, Lucas DJ, Shafi NI. “Respiratory Syncytial Virus Bronchiolitis Complicated by Necrotizing Enterocolitis: A Case Series.” Pediatrics (2021). PMID: 33824182 ↗
L4CASE_REPORTCited in: Growth, Development & Nutrition Impact, Complications - [231]
Sweet DG, Turner MA, Straňák Z et al.. “A first-in-human clinical study of a new SP-B and SP-C enriched synthetic surfactant (CHF5633) in preterm babies with respiratory distress syndrome.” Archives of disease in childhood. Fetal and neonatal edition (2017). PMID: 28465315 ↗
L2TRIAL_NONRANDOMCited in: Growth, Development & Nutrition Impact, Complications - [232]
Rivas-Calderon M, Yamazaki-Nakashimada MA, Orozco-Covarrubias L et al.. “Bronchiolitis Obliterans With Anti-Epiplakin Antibodies in a Boy With Paraneoplastic Pemphigus.” Pediatrics (2022). PMID: 35118492 ↗
L4OTHERCited in: Growth, Development & Nutrition Impact - [233]
Guttmann A, Razzaq A, Lindsay P et al.. “Development of measures of the quality of emergency department care for children using a structured panel process.” Pediatrics (2006). PMID: 16818556 ↗
L5OTHERCited in: Growth, Development & Nutrition Impact - [234]
Carroll KN, Gebretsadik T, Griffin MR et al.. “Maternal asthma and maternal smoking are associated with increased risk of bronchiolitis during infancy.” Pediatrics (2007). PMID: 17545377 ↗
L3OTHERCited in: Growth, Development & Nutrition Impact, Complications - [235]
Pinto RA, Arredondo SM, Bono MR et al.. “T helper 1/T helper 2 cytokine imbalance in respiratory syncytial virus infection is associated with increased endogenous plasma cortisol.” Pediatrics (2006). PMID: 16618789 ↗
L4OTHERCited in: Growth, Development & Nutrition Impact - [236]
Hasegawa K, Mansbach JM, Bochkov YA et al.. “Association of Rhinovirus C Bronchiolitis and Immunoglobulin E Sensitization During Infancy With Development of Recurrent Wheeze.” JAMA pediatrics (2019). PMID: 30933255 ↗
L2OTHERCited in: Growth, Development & Nutrition Impact, Special Populations - [237]
Smyth RL, Openshaw PJ. “Bronchiolitis.” Lancet (London, England) (2006). PMID: 16860701 ↗
L5REVIEW_NARRATIVECited in: Growth, Development & Nutrition Impact - [238]
Adderson E, Allison KJ, Branum K et al.. “Intranasal Sendai Virus Vaccination of Seropositive Children 1 to 2 Years of Age in a Phase I Clinical Trial Boosts Immune Responses Toward Human Parainfluenza Virus Type 1.” Vaccines (2025). PMID: 40333329 ↗
L4TRIAL_NONRANDOMCited in: Growth, Development & Nutrition Impact, Prevention, Screening & Surveillance - [239]
Liem JJ, Huq SI, Ekuma O et al.. “Transient tachypnea of the newborn may be an early clinical manifestation of wheezing symptoms.” The Journal of pediatrics (2007). PMID: 17586187 ↗
L3OTHERCited in: Growth, Development & Nutrition Impact - [240]
Palomar LM, Nogee LM, Sweet SC et al.. “Long-term outcomes after infant lung transplantation for surfactant protein B deficiency related to other causes of respiratory failure.” The Journal of pediatrics (2006). PMID: 17011330 ↗
L3OTHERCited in: Growth, Development & Nutrition Impact, Complications - [241]
Jotterand Chaparro C, Bertoni Maluf VA, Pabion C et al.. “The effectiveness of high versus lower enteral protein intake, considering energy intake, on clinical outcomes in critically ill children: A systematic review and meta-analysis.” Clinical nutrition (Edinburgh, Scotland) (2025). PMID: 41109033 ↗
L1SR_OBSCited in: Growth, Development & Nutrition Impact - [242]
Rojas-McKenzie M, Fraga JP, Iturriaga C et al.. “Early Use of Proton Pump Inhibitors Increases Risk of Upper Respiratory Tract Infections in Children: A Birth Cohort Study.” Pediatric pulmonology (2026). PMID: 42360697 ↗
L2COHORTCited in: Growth, Development & Nutrition Impact, Special Populations - [243]
Li L, Shen K, Chen Q et al.. “Association of early-life human rhinovirus and respiratory syncytial virus infections with childhood asthma: a cohort study in Suzhou, China.” BMJ open (2026). PMID: 42161543 ↗
L3COHORTCited in: Growth, Development & Nutrition Impact, Complications, Prognosis & Natural History, Special Populations - [244]
Schwarze J. “Lung dendritic cells in respiratory syncytial virus bronchiolitis.” The Pediatric infectious disease journal (2008). PMID: 18820586 ↗
L5OTHERCited in: Growth, Development & Nutrition Impact, Prevention, Screening & Surveillance - [245]
Hegde S, Prodhan P. “Serious air leak syndrome complicating high-flow nasal cannula therapy: a report of 3 cases.” Pediatrics (2013). PMID: 23382446 ↗
L4CASE_REPORTCited in: Complications - [246]
Duarte-Salles T, Vizcaya D, Pistillo A et al.. “Thirty-Day Outcomes of Children and Adolescents With COVID-19: An International Experience.” Pediatrics (2021). PMID: 34049958 ↗
L3OTHERCited in: Complications - [247]
Cohen E, Rodean J, Diong C et al.. “Low-Value Diagnostic Imaging Use in the Pediatric Emergency Department in the United States and Canada.” JAMA pediatrics (2019). PMID: 31157877 ↗
L3OTHERCited in: Complications, Prognosis & Natural History - [248]
Oakley E, Bata S, Rengasamy S et al.. “Nasogastric Hydration in Infants with Bronchiolitis Less Than 2 Months of Age.” The Journal of pediatrics (2016). PMID: 27522439 ↗
L3OTHERCited in: Complications - [249]
Xu B, Cao L, Shang Y et al.. “Low-dose versus high-dose methylprednisolone for children with severe Mycoplasma pneumoniae pneumonia (MCMP): A randomized controlled trial.” Pediatric investigation (2025). PMID: 40969290 ↗
L1RCTCited in: Complications, Prognosis & Natural History - [250]
Sayed MS, Elgendy MA, Gamil N et al.. “Efficacy and safety of a single dose of nirsevimab against respiratory syncytial virus infection in infants: a meta-analysis and time-to-event analysis.” Italian journal of pediatrics (2025). PMID: 41469925 ↗
L1SR_OBSCited in: Complications - [251]
Broughton S, Bhat R, Roberts A et al.. “Diminished lung function, RSV infection, and respiratory morbidity in prematurely born infants.” Archives of disease in childhood (2005). PMID: 16188957 ↗
L2OTHERCited in: Complications - [252]
Graham S, Sartorius B, Snelling T et al.. “A retrospective cohort study and spatial analysis of climate and community-level determinants of respiratory syncytial virus notifications among Queensland infants, prior to the introduction of the RSV mother and infant protection program (RSV-MIPP) immunisation initiative.” BMC public health (2026). PMID: 41566313 ↗
L2COHORTCited in: Complications - [253]
Çoksüer F, Öztürk GK, Ocak E et al.. “Pulmonary outcomes of pediatric patients with postinfectious bronchiolitis obliterans treated with pulse methylprednisolone and intravenous immunoglobulin: a single-center cohort study.” European journal of pediatrics (2025). PMID: 40773144 ↗
L2COHORTCited in: Complications - [254]
Spurling GK, Doust J, Del Mar CB et al.. “Antibiotics for bronchiolitis in children.” The Cochrane database of systematic reviews (2011). PMID: 21678346 ↗
L1SR_OBSCited in: Complications - [255]
Farley R, Spurling GK, Eriksson L et al.. “Antibiotics for bronchiolitis in children under two years of age.” The Cochrane database of systematic reviews (2014). PMID: 25300167 ↗
L1SR_OBSCited in: Complications - [256]
Nicolai A, Frassanito A, Nenna R et al.. “Risk Factors for Virus-induced Acute Respiratory Tract Infections in Children Younger Than 3 Years and Recurrent Wheezing at 36 Months Follow-Up After Discharge.” The Pediatric infectious disease journal (2017). PMID: 27798551 ↗
L2OTHERCited in: Complications - [257]
Richard N, Komurian-Pradel F, Javouhey E et al.. “The impact of dual viral infection in infants admitted to a pediatric intensive care unit associated with severe bronchiolitis.” The Pediatric infectious disease journal (2008). PMID: 18277932 ↗
L3OTHERCited in: Complications - [258]
Lawrence J, Walpola R, Boyce SL et al.. “Home Care for Bronchiolitis: A Systematic Review.” Pediatrics (2022). PMID: 36065737 ↗
L2SR_OBSCited in: Prognosis & Natural History, Special Populations - [259]
Harrison W, Angoulvant F, House S et al.. “Hypertonic Saline in Bronchiolitis and Type I Error: A Trial Sequential Analysis.” Pediatrics (2018). PMID: 30115731 ↗
L1SR_OBSCited in: Prognosis & Natural History - [260]
Hester G, Nickel AJ, Watson D et al.. “Use of a Clinical Guideline and Orderset to Reduce Hospital Admissions for Croup.” Pediatrics (2022). PMID: 35970819 ↗
L2REVIEW_NARRATIVECited in: Prognosis & Natural History - [261]
Sandweiss DR, Mundorff MB, Hill T et al.. “Decreasing hospital length of stay for bronchiolitis by using an observation unit and home oxygen therapy.” JAMA pediatrics (2013). PMID: 23479000 ↗
L2OTHERCited in: Prognosis & Natural History - [262]
de Sonnaville ESV, Kӧnigs M, Aarnoudse-Moens CSH et al.. “Long-Term Follow-Up of Daily Life Functioning After Pediatric Intensive Care Unit Admission.” The Journal of pediatrics (2023). PMID: 37187287 ↗
L2OTHERCited in: Prognosis & Natural History, Special Populations - [263]
Florin TA, Byczkowski T, Ruddy RM et al.. “Variation in the management of infants hospitalized for bronchiolitis persists after the 2006 American Academy of Pediatrics bronchiolitis guidelines.” The Journal of pediatrics (2014). PMID: 25015578 ↗
L2OTHERCited in: Prognosis & Natural History, Special Populations - [264]
Montejo M, Paniagua N, Saiz-Hernando C et al.. “Initiatives to reduce treatments in bronchiolitis in the emergency department and primary care.” Archives of disease in childhood (2019). PMID: 31666241 ↗
L2OTHERCited in: Prognosis & Natural History, Special Populations - [265]
Liu TW, Huang SY, Chou CM et al.. “The Association Between the Surgical Timing for Congenital Malformation of Lung and Asthma Prevalence-A Nationwide Cohort Study.” Pediatric pulmonology (2025). PMID: 40734376 ↗
L2COHORTCited in: Prognosis & Natural History - [266]
Jat KR, Dsouza JM, Mathew JL. “Continuous positive airway pressure (CPAP) for acute bronchiolitis in children.” The Cochrane database of systematic reviews (2022). PMID: 35377462 ↗
L2SR_OBSCited in: Prognosis & Natural History, Special Populations - [267]
Ventre K, Haroon M, Davison C. “Surfactant therapy for bronchiolitis in critically ill infants.” The Cochrane database of systematic reviews (2006). PMID: 16856080 ↗
L1SR_OBSCited in: Prognosis & Natural History, Special Populations - [268]
Fuller H, Del Mar C. “Immunoglobulin treatment for respiratory syncytial virus infection.” The Cochrane database of systematic reviews (2006). PMID: 17054220 ↗
L1SR_OBSCited in: Prognosis & Natural History, Special Populations - [269]
Bergroth E, Aakula M, Korppi M et al.. “Post-bronchiolitis Use of Asthma Medication: A Prospective 1-year Follow-up Study.” The Pediatric infectious disease journal (2016). PMID: 26658529 ↗
L2OTHERCited in: Prognosis & Natural History - [270]
Fouzas S, Priftis KN, Anthracopoulos MB. “Pulse oximetry in pediatric practice.” Pediatrics (2011). PMID: 21930554 ↗
L5REVIEW_NARRATIVECited in: Special Populations - [271]
Andina Martínez D, Claret Teruel G, Gijón Mediavilla M et al.. “Nirsevimab and Acute Bronchiolitis Episodes in Pediatric Emergency Departments.” Pediatrics (2024). PMID: 39257372 ↗
L2OTHERCited in: Special Populations - [272]
Ralston SL, House SA, Harrison W et al.. “The Evolution of Quality Benchmarks for Bronchiolitis.” Pediatrics (2021). PMID: 34462342 ↗
L2OTHERCited in: Special Populations - [273]
Lenglart L, Titomanlio L, Bognar Z et al.. “Surge of Pediatric Respiratory Tract Infections after the COVID-19 Pandemic and the Concept of "Immune Debt".” The Journal of pediatrics (2024). PMID: 39579868 ↗
L2OTHERCited in: Special Populations, Prevention, Screening & Surveillance - [274]
Mansbach JM, Qi YS, Espinola JA et al.. “Late Pre-term Infants with Severe Bronchiolitis and Risk of Asthma by Age 5 Years.” The Journal of pediatrics (2021). PMID: 34599916 ↗
L2OTHERCited in: Special Populations - [275]
Cunningham S, McMurray A. “Observational study of two oxygen saturation targets for discharge in bronchiolitis.” Archives of disease in childhood (2011). PMID: 21388970 ↗
L2OTHERCited in: Special Populations - [276]
García-Garcia ML, González-Carrasco E, Quevedo S et al.. “Clinical and Virological Characteristics of Early and Moderate Preterm Infants Readmitted With Viral Respiratory Infections.” The Pediatric infectious disease journal (2015). PMID: 25923427 ↗
L2OTHERCited in: Special Populations - [277]
Bryan MA, Hofstetter AM, deHart MP et al.. “Vaccination Status and Resource Use During Hospital Visits for Respiratory Illnesses.” Pediatrics (2019). PMID: 31624218 ↗
L2OTHERCited in: Prevention, Screening & Surveillance - [278]
Choudhuri JA, Ogden LG, Ruttenber AJ et al.. “Effect of altitude on hospitalizations for respiratory syncytial virus infection.” Pediatrics (2006). PMID: 16452353 ↗
L2OTHERCited in: Prevention, Screening & Surveillance - [279]
Calvo C, Alcolea S, Casas I et al.. “A 14-year Prospective Study of Human Coronavirus Infections in Hospitalized Children: Comparison With Other Respiratory Viruses.” The Pediatric infectious disease journal (2020). PMID: 32453196 ↗
L2COHORTCited in: Prevention, Screening & Surveillance - [280]
Fusco E, Loiodice M, Romero A et al.. “Effectiveness of Nirsevimab in Preventing Respiratory Syncytial Virus-related Burden: A Test-negative Case-control Study in Infants With Bronchiolitis in Lombardy Region, Italy.” The Pediatric infectious disease journal (2025). PMID: 41104905 ↗
L3CASE_CONTROLCited in: Prevention, Screening & Surveillance - [281]
Lukac CD, Simms B, Kwong GPS et al.. “Hospitalizations for all-cause pediatric acute respiratory diseases in Alberta, Canada, before, during, and after the COVID-19 pandemic: a population-level retrospective cohort study from 2010 to 2024.” Lancet regional health. Americas (2025). PMID: 40260184 ↗
L2COHORTCited in: Prevention, Screening & Surveillance - [282]
Marouk A, Verrat B, Pontais I et al.. “Effectiveness of nirsevimab in reducing hospitalizations in emergency departments due to bronchiolitis among infants under 3 months: a retrospective study.” European journal of pediatrics (2025). PMID: 40044918 ↗
L2COHORTCited in: Prevention, Screening & Surveillance - [283]
Bar-On ES, Goldberg E, Hellmann S et al.. “Combined DTP-HBV-HIB vaccine versus separately administered DTP-HBV and HIB vaccines for primary prevention of diphtheria, tetanus, pertussis, hepatitis B and Haemophilus influenzae B (HIB).” The Cochrane database of systematic reviews (2012). PMID: 22513932 ↗
L1SR_OBSCited in: Prevention, Screening & Surveillance - [284]
Phijffer EWEM, Wildenbeest JG, Brouwer CNM et al.. “The Full Burden of RSV-related Pediatric Intensive Care Unit Admissions During Infancy: A Prospective National Study (BRICK Study).” The Pediatric infectious disease journal (2025). PMID: 40359239 ↗
L2OTHERCited in: Prevention, Screening & Surveillance - [285]
Sheikh Z, Potter E, Li Y et al.. “Validity of Clinical Severity Scores for Respiratory Syncytial Virus: A Systematic Review.” The Journal of infectious diseases (2024). PMID: 37797314 ↗
L2aCited in: Definition, Classification & Nomenclature - [286]
Bylsma LC, Suh M, Movva N et al.. “Mortality Among US Infants and Children Under 5 Years of Age with Respiratory Syncytial Virus and Bronchiolitis: A Systematic Literature Review.” The Journal of infectious diseases (2022). PMID: 35968871 ↗
L4Cited in: Definition, Classification & Nomenclature - [287]
Chang PW, Schroeder AR, Lucas BP et al.. “Impact of Diagnostic Criteria on UTI Prevalence in Young Infants With Jaundice: A Meta-analysis.” Hospital pediatrics (2022). PMID: 35322269 ↗
L2aCited in: Definition, Classification & Nomenclature - [288]
Ghabousian A, Bezerra GN, Zhu Z et al.. “Impact of varying childhood asthma definitions on incidence and clinical outcomes.” Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology (2025). PMID: 40818620 ↗
L2bCited in: Definition, Classification & Nomenclature - [289]
Delaney K, Roberts AR, Morrison JM et al.. “Systemic Corticosteroids for Acute Viral Bronchiolitis: A Retrospective Multicenter Cohort Study.” Hospital pediatrics (2025). PMID: 40527516 ↗
L2bCited in: Definition, Classification & Nomenclature - [290]
Shen J, Du Y, Sun Y et al.. “Modified lung ultrasound score for bronchopulmonary dysplasia predicts late respiratory outcomes in preterm infants.” Pediatric pulmonology (2023). PMID: 37294069 ↗
L2bCited in: Definition, Classification & Nomenclature - [291]
Ardillon A, Ramblière L, Kermorvant-Duchemin E et al.. “Inappropriate antibiotic prescribing and its determinants among outpatient children in 3 low- and middle-income countries: A multicentric community-based cohort study.” PLoS medicine (2023). PMID: 37279198 ↗
L4Cited in: Definition, Classification & Nomenclature - [292]
Englund JA, Cohen RA, Bianco V et al.. “Evaluation of Clinical Case Definitions for Respiratory Syncytial Virus Lower Respiratory Tract Infection in Young Children.” Journal of the Pediatric Infectious Diseases Society (2023). PMID: 37142551 ↗
L4Cited in: Definition, Classification & Nomenclature - [293]
Dong Z, Myklebust Å, Johnsen IB et al.. “Type 2 cytokine genes as allergic asthma risk factors after viral bronchiolitis in early childhood.” Frontiers in immunology (2023). PMID: 36685501 ↗
L2bCited in: Definition, Classification & Nomenclature - [294]
Andina-Martinez D, Alonso-Cadenas JA, Cobos-Carrascosa E et al.. “SARS-CoV-2 acute bronchiolitis in hospitalized children: Neither frequent nor more severe.” Pediatric pulmonology (2021). PMID: 34664782 ↗
L4Cited in: Definition, Classification & Nomenclature - [295]
Alkhazali IE, Alrawashdeh A, Hashairi Fauzi M et al.. “Quality Indicators for Pediatric Bronchiolitis and Croup Care in the Emergency Department; a Systematic Review and Meta-Analysis.” Archives of academic emergency medicine (2024). PMID: 39290773 ↗
L2aCited in: Definition, Classification & Nomenclature - [296]
Agossah C, Marie J, Bendoukha Y et al.. “The severity of the first occurrence of bronchiolitis increased the risk of developing asthma symptoms.” Acta paediatrica (Oslo, Norway : 1992) (2025). PMID: 39748149 ↗
L3bCited in: Definition, Classification & Nomenclature - [297]
Cadotte N, Moore H, Stone BL et al.. “Prevalence of and Risks for Bacterial Infections in Hospitalized Children With Bronchiolitis.” Hospital pediatrics (2024). PMID: 38973365 ↗
L3bCited in: Definition, Classification & Nomenclature - [298]
Shepard LN, Mehta S, Graham K et al.. “Noninvasive Positive Pressure Ventilation Use and In-Hospital Cardiac Arrest in Bronchiolitis.” Critical care explorations (2024). PMID: 38747691 ↗
L3bCited in: Definition, Classification & Nomenclature - [299]
Haag MB, Goldfarb J, Austin JP et al.. “Increased Adiposity Associated With Increased Length of Stay for Infants With Bronchiolitis.” Hospital pediatrics (2020). PMID: 32540935 ↗
L3bCited in: Pathophysiology & Developmental Mechanism - [300]
Werder RB, Lynch JP, Simpson JC et al.. “PGD2/DP2 receptor activation promotes severe viral bronchiolitis by suppressing IFN-λ production.” Science translational medicine (2018). PMID: 29743346 ↗
L3bCited in: Pathophysiology & Developmental Mechanism - [301]
Juliana A, Plötz FB, Achten N et al.. “Requirement of respiratory support in acute bronchiolitis in infants is linked to endothelial and neutrophil activation.” Pediatric pulmonology (2021). PMID: 34491635 ↗
L3bCited in: Pathophysiology & Developmental Mechanism - [302]
Arunsiripate TT, Groeltz-Thrush J, Saeng-Chuto K et al.. “Diagnostic investigation of porcine hemagglutinating encephalomyelitis virus as potential pathogen associated with respiratory clinical signs and pulmonary lesions in pigs.” Microbial pathogenesis (2025). PMID: 40120700 ↗
L3bCited in: Pathophysiology & Developmental Mechanism - [303]
Ventre KM, Wolf GK, Arnold JH. “Pediatric respiratory diseases: 2011 update for the Rogers' Textbook of Pediatric Intensive Care.” Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies (2011). PMID: 21378592 ↗
L5Cited in: Pathophysiology & Developmental Mechanism - [304]
Gao J, Petraki S, Sun X et al.. “Derivation of induced pluripotent stem cells from ferret somatic cells.” American journal of physiology. Lung cellular and molecular physiology (2020). PMID: 32073882 ↗
L5Cited in: Pathophysiology & Developmental Mechanism - [305]
Piazza M, Gori A, Capristo C et al.. “Bronchiolitis and recurrent respiratory infections: The role of oxidative stress from early life inflammation to long-term outcomes - A narrative review.” The World Allergy Organization journal (2026). PMID: 41550683 ↗
L5Cited in: Pathophysiology & Developmental Mechanism - [306]
Gartlan KH, Bommiasamy H, Paz K et al.. “A critical role for donor-derived IL-22 in cutaneous chronic GVHD.” American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons (2017). PMID: 28941323 ↗
L5Cited in: Pathophysiology & Developmental Mechanism - [307]
Simpson J, Loh Z, Ullah MA et al.. “Respiratory Syncytial Virus Infection Promotes Necroptosis and HMGB1 Release by Airway Epithelial Cells.” American journal of respiratory and critical care medicine (2020). PMID: 32105156 ↗
L5Cited in: Pathophysiology & Developmental Mechanism - [308]
Kimura D, Saravia J, Jaligama S et al.. “New mouse model of pulmonary hypertension induced by respiratory syncytial virus bronchiolitis.” American journal of physiology. Heart and circulatory physiology (2018). PMID: 29906223 ↗
L5Cited in: Pathophysiology & Developmental Mechanism - [309]
Lee JH, Rehder KJ, Williford L et al.. “Use of high flow nasal cannula in critically ill infants, children, and adults: a critical review of the literature.” Intensive care medicine (2012). PMID: 23143331 ↗
L5Cited in: Pathophysiology & Developmental Mechanism - [310]
Cheemarla NR, Uche IK, McBride K et al.. “In utero tobacco smoke exposure alters lung inflammation, viral clearance, and CD8+ T-cell responses in neonatal mice infected with respiratory syncytial virus.” American journal of physiology. Lung cellular and molecular physiology (2019). PMID: 31090436 ↗
L5Cited in: Pathophysiology & Developmental Mechanism - [311]
Zhivaki D, Lemoine S, Lim A et al.. “Respiratory Syncytial Virus Infects Regulatory B Cells in Human Neonates via Chemokine Receptor CX3CR1 and Promotes Lung Disease Severity.” Immunity (2017). PMID: 28228284 ↗
L5Cited in: Pathophysiology & Developmental Mechanism - [312]
Sliwicki AL, Kreger JE, Essoh SN et al.. “Viral and Host-Related Factors in the Nasal Inflammatory Response to Critical Bronchiolitis in Infants and Children.” Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies (2026). PMID: 41860323 ↗
L4Cited in: Epidemiology, Etiology & Risk Factors - [313]
Merino-Hernández A, Ramos-Navarro C, Rodríguez-Corrales E et al.. “Beyond bronchopulmonary dysplasia: impact of human milk feeding on long-term respiratory morbidity in very preterm infants.” European journal of pediatrics (2026). PMID: 41786923 ↗
L2bCited in: Epidemiology, Etiology & Risk Factors - [314]
Pei WT, Liu CL, Li XL. “Efficacy and safety of a new cladribine-based conditioning regimen for allogeneic hematopoietic stem cell transplantation in children with relapsed or refractory acute myeloid leukemia.” Frontiers in medicine (2026). PMID: 41859162 ↗
L2bCited in: Epidemiology, Etiology & Risk Factors - [315]
Hazan G, Ofri M, Hertz L et al.. “Asthma-related Pediatric Healthcare Utilization after Hospitalization for RSV and Other Viral Lower Respiratory Tract Infections.” Open forum infectious diseases (2026). PMID: 42444788 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [316]
Macías Reyes MJ, Vidal-Alaball J, Sola Reguant L et al.. “Temporal Trends in the Use of Healthcare Services for Respiratory Infections in the Paediatric Population of Anoia (2017-2024): Primary and Hospital Care.” Viruses (2026). PMID: 42357597 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [317]
Ryan JF, Cheng TA, Crowe RP et al.. “Prehospital Assessment and Treatment of Infants and Toddlers in Respiratory Distress: A Retrospective Analysis.” Prehospital emergency care (2026). PMID: 42330187 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [318]
Maya MA, Raboni SM, Giamberardino HIG et al.. “Clinical and genomic characterization of pediatric adenovirus-associated severe acute respiratory infection: a binational study from Brazil and Colombia, 2022-2023.” International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases (2026). PMID: 42309478 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [319]
Li L, Zhang Z, Yuan F et al.. “Clinical risk factors and predictive value of thin-section CT for bronchial mucus plugs in pediatric mycoplasma pneumoniae pneumonia.” BMC infectious diseases (2026). PMID: 42104258 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [320]
Dekker L, Versluys BA, de Koning CCH et al.. “Risk factors for alloimmune lung syndromes after allogeneic hematopoietic cell transplantation in children.” Bone marrow transplantation (2026). PMID: 41896325 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [321]
Petrone D, Sani I, De Vittori V et al.. “Impact of Nirsevimab on bronchiolities in pediatric primary care in Lazio Region: an observational study.” Italian journal of pediatrics (2026). PMID: 41820965 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [322]
Strati MF, Mariani M, Brisca G et al.. “Optimizing pediatric bronchiolitis management through an integrated hub-and-spoke network: evidence from a regional Italian experience.” European journal of pediatrics (2026). PMID: 41699321 ↗
L4Cited in: Epidemiology, Etiology & Risk Factors - [323]
Kim JH, Shin J, Ha E et al.. “Acute Bronchiolitis in Young Children and Future Mental Health Outcome: A 15-Year National Population Study Regardless of Allergic Conditions.” Pediatric pulmonology (2026). PMID: 41668629 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [324]
Boracchini R, Barbieri E, Canova B et al.. “Changes in pediatric primary care contacts: has the RSV-immunization modified the age-related access?” Italian journal of pediatrics (2026). PMID: 41629983 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [325]
Mazela J, Jackowska T, Czech M et al.. “Clinical Burden and Healthcare Utilization Associated with Hospitalizations of RSV-Infected Polish Children During the 2022/23 Season.” Viruses (2025). PMID: 41600825 ↗
L3bCited in: Epidemiology, Etiology & Risk Factors - [326]
Petat H, Schuers M, Le Bas F et al.. “Characterizing acute respiratory infections in primary care for better management of viral infections.” NPJ primary care respiratory medicine (2025). PMID: 40473668 ↗
L2bCited in: Clinical Presentation - [327]
Zhu Z, Freishtat RJ, Harmon B et al.. “Nasal airway microRNA profiling of infants with severe bronchiolitis and risk of childhood asthma: a multicentre prospective study.” The European respiratory journal (2023). PMID: 37321621 ↗
L2bCited in: Clinical Presentation - [328]
Loveys K, Borland ML, Oakley E et al.. “Risk Factors for Severe Bronchiolitis in Australian and Aotearoa New Zealand Infants: A Systematic Review.” Journal of paediatrics and child health (2025). PMID: 40778659 ↗
L2aCited in: Clinical Presentation - [329]
Kabir FL, Arm LK, Alam J et al.. “Misdiagnosis of bronchiolitis and misuse of antibiotics - experience from the largest paediatric hospital of Bangladesh.” Journal of global health (2026). PMID: 42596748 ↗
L3bCited in: Clinical Presentation - [330]
Gatt D, Ben-Shitrit I, Golan-Tripto I et al.. “Meconium Aspiration Syndrome and the Association With Preschool Asthma.” Chest (2026). PMID: 42025996 ↗
L3bCited in: Clinical Presentation - [331]
Nigri D, Winter MC, Ross PA et al.. “Inhaled L-Epinephrine As a Rescue Therapy in Critical Bronchiolitis.” Critical care explorations (2026). PMID: 41586743 ↗
L4Cited in: Clinical Presentation - [332]
Wang Y, Jiang Y, Xia R et al.. “Clinical features and risk factors of adenovirus-related plastic bronchitis in children.” Italian journal of pediatrics (2025). PMID: 40289082 ↗
L3bCited in: Clinical Presentation - [333]
Zhao W, Wang R, Chen M. “Clinical analysis of air-leak syndrome following allogeneic hematopoietic stem cell transplantation in pediatric patients.” Pediatric blood & cancer (2024). PMID: 38676303 ↗
L4Cited in: Clinical Presentation - [334]
Dovizio M, Veronesi C, Bartolini F et al.. “Clinical and economic burden of respiratory syncytial virus in children aged 0-5 years in Italy.” Italian journal of pediatrics (2024). PMID: 38528616 ↗
L3bCited in: Clinical Presentation - [335]
Kobiałka M, Jackowska T, Wrotek A. “Risk Factors for Severe Respiratory Syncytial Virus Infection in Hospitalized Children.” Viruses (2023). PMID: 37632055 ↗
L3bCited in: Clinical Presentation - [336]
Li Y, Zhang J, Liu H et al.. “Age-related pharyngeal microbiome and host transcriptomic signatures underlying fever responses in RSV bronchiolitis.” Virologica Sinica (2026). PMID: 42140385 ↗
L2bCited in: Clinical Presentation - [337]
Hintz LK, Lorenz D, Lipshaw MJ et al.. “High Flow Nasal Cannula Use in Bronchiolitis: Predicting Need for Early Escalation of Care.” Pediatric emergency care (2026). PMID: 41527360 ↗
L2bCited in: Clinical Presentation - [338]
Abraham S, John JJ, Johnson JJ et al.. “Clinical profile and risk factors of severe adenoviral infections among hospitalised children in South India: a cross-sectional study.” BMJ paediatrics open (2026). PMID: 42230299 ↗
L3bCited in: Clinical Presentation - [339]
Baudin F, Pouyau R, Subtil F et al.. “Prone Positioning in Infants With Acute Bronchiolitis: The PROPOSITIS Randomized Clinical Trial.” JAMA (2026). PMID: 42307570 ↗
L1bCited in: Diagnosis & Workup - [340]
Elmeazawy R, Aborady AA, Abd-Razik AM et al.. “Lung ultrasound versus chest X-ray in pediatric lower respiratory tract infections at a tertiary center: a prospective observational study.” Italian journal of pediatrics (2026). PMID: 42498969 ↗
L3bCited in: Diagnosis & Workup - [341]
DeBoer E, Wolter-Warmerdam K, Bernstein R et al.. “Respiratory-Related Hospital Admissions in Children and Young Adults With Down Syndrome.” Hospital pediatrics (2026). PMID: 42481043 ↗
L3bCited in: Diagnosis & Workup - [342]
Lee J, Fazzari MJ, Desai AD et al.. “Ratio of Postdischarge Emergency Department Visits to Readmissions by Diagnosis.” Hospital pediatrics (2026). PMID: 42476574 ↗
L3bCited in: Diagnosis & Workup - [343]
Osten AW, Hall M, Elsayed A et al.. “The Cost of Combining Asthma and Bronchiolitis Diagnoses in Hospitalized Children.” Academic pediatrics (2026). PMID: 42385921 ↗
L3bCited in: Diagnosis & Workup - [344]
Beydon N, Roux EL, Boizeau P et al.. “Impedance Pneumography in Healthy and Sick Children Aged Between 2 and 35 Months.” Pediatric pulmonology (2026). PMID: 42287174 ↗
L3bCited in: Diagnosis & Workup - [345]
Bowles AK, Rodean J, Siegel EJ et al.. “Examining Disparities in Pediatric Asthma, Pneumonia, and Bronchiolitis Care in General Hospitals.” Hospital pediatrics (2026). PMID: 42270087 ↗
L3bCited in: Diagnosis & Workup - [346]
Bueno-Campaña M, Suarez-Cabezas S, de la Torre-Martin L et al.. “Lung ultrasound in diagnosis of wheezing triggered by infection in children less than 2 years: An observational study.” The American journal of emergency medicine (2026). PMID: 42034036 ↗
L3bCited in: Diagnosis & Workup - [347]
Boracchini R, Brigadoi G, Salvadori S et al.. “RSV Detection and Antibiotic Prescribing Decisions for Pediatric Respiratory Tract Infections.” JAMA network open (2026). PMID: 41774441 ↗
L3bCited in: Diagnosis & Workup - [348]
Soydan E, Gökpınar EE, Sevinç ZG et al.. “Impact of a nurse-driven high-flow nasal cannula weaning protocol on HFNC duration in infants with bronchiolitis: a randomized controlled trial.” European journal of pediatrics (2026). PMID: 41866402 ↗
L1bCited in: Severity Grading, Staging & Risk Stratification - [349]
Giugni C, Cecchi C, Nanni L et al.. “Standardizing HFNC for bronchiolitis: a quality improvement protocol in an Italian children's hospital.” European journal of pediatrics (2026). PMID: 42171785 ↗
L4Cited in: Severity Grading, Staging & Risk Stratification - [350]
Dundar MA, Erdem S, Cetin B et al.. “Pediatric bronchiolitis disease severity is associated with immune checkpoint dysregulation.” Pediatric research (2026). PMID: 41826706 ↗
L2bCited in: Severity Grading, Staging & Risk Stratification - [351]
Astudillo P, Rodriguez-Fernandez M, Castro-Rodríguez JA et al.. “Wheezing on admission: a marker for bronchiolitis severity and asthma development.” Pediatric research (2025). PMID: 40319140 ↗
L2bCited in: Severity Grading, Staging & Risk Stratification - [352]
Mortamet G, Milési C, Cassibba J et al.. “Noninvasive Respiratory Support Weaning in Infants With Severe Bronchiolitis: High Flow Nasal Cannula May Reduce the Length of Stay.” Pediatric pulmonology (2025). PMID: 40277149 ↗
L2bCited in: Severity Grading, Staging & Risk Stratification - [353]
Bähre J, Lange M, Salaschek P et al.. “Distinct seasonality and increased respiratory failure in RSV patients < 2 years of age after emergence of SARS-CoV-2: data from the multicentric, prospective PAPI study.” European journal of pediatrics (2025). PMID: 40080186 ↗
L2bCited in: Severity Grading, Staging & Risk Stratification - [354]
Ishizuka M, Conlon TW, Glau CL et al.. “Validation of Lung Ultrasound Score for Disease Severity and Outcomes in Pediatric Acute Respiratory Failure.” Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies (2026). PMID: 41697090 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [355]
Presti S, Parisi GF, Tosto M et al.. “Effect of Nirsevimab as a Primary Preventive Strategy on the Incidence, Severity, and Viral Etiology of Bronchiolitis: A Four-Year Observational Study.” Pediatric pulmonology (2026). PMID: 41457692 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [356]
Toomey V, Howard S, Klein MJ et al.. “Financial Consequence of COVID-19 on United States PICUs: A 2017 to 2023 Study Using the Pediatric Health Information System and the Virtual Pediatric System Database.” Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies (2025). PMID: 41440375 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [357]
Sunderajan T, Choi DS, LaFerla C et al.. “Routine Chest X-Rays in Critical Bronchiolitis Do Not Improve Outcomes.” Journal of clinical medicine (2025). PMID: 41227205 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [358]
Zayani S, Thabet F, Daya A et al.. “Regional Pulmonary Involvement in Bronchiolitis: Insights From Lung Ultrasound.” Pediatric pulmonology (2025). PMID: 41090238 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [359]
García Acevedo M, Sánchez Códez MI, Peromingo Matute E et al.. “Impact of universal nirsevimab prophylaxis on clinical and ultrasound presentations of lower respiratory tract infections in hospitalized pediatric patients.” European journal of pediatrics (2025). PMID: 40960546 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [360]
Cappelli E, Ciofi Degli Atti M, Ravà L et al.. “Factors Predicting Readmission to the Emergency Department After a Diagnosis of Acute Respiratory Infection: A Two-year Experience at a Pediatric Tertiary Care Hospital in Italy.” The Pediatric infectious disease journal (2025). PMID: 40865117 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [361]
Mazenq J, Crebassa M, Hadchouel A et al.. “Younger Age and Viral Triggers Were Associated With Post-Infectious Bronchiolitis Obliterans in French Children.” Acta paediatrica (Oslo, Norway : 1992) (2025). PMID: 40548825 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [362]
D'Alessandro M, Bellini T, Bustaffa M et al.. “Lung Ultrasound Score and Bronchiolitis: What can be Predicted in a Single Center Experience.” Journal of intensive care medicine (2025). PMID: 40473423 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [363]
Bolic MS, Lew J, Richardson DB. “Scoping a paediatric emergency medicine unit.” Emergency medicine Australasia : EMA (2025). PMID: 40104949 ↗
L3bCited in: Severity Grading, Staging & Risk Stratification - [364]
Louman S, van Stralen KJ, Koppelman GH et al.. “Oxygen saturation thresholds in children with acute respiratory distress (OxyKids): a multicentre, open, parallel-group, randomised clinical trial.” The Lancet. Respiratory medicine (2026). PMID: 42119581 ↗
L1bCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [365]
Khoshnevisasl P, Sadeghzadeh M, Kamali K et al.. “A randomized clinical trial to assess the effect of zinc and vitamin D supplementation in addition to hypertonic saline on treatment of acute bronchiolitis.” BMC infectious diseases (2022). PMID: 35692038 ↗
L1bCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [366]
Ziv N, Zagon-Rogel M, Waisman Y et al.. “The effect of environmental noise isolation on bronchiolitis severity in hospitalised children.” Acta paediatrica (Oslo, Norway : 1992) (2022). PMID: 35642684 ↗
L1bCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [367]
Eşki A, Öztürk GK, Turan C et al.. “High-flow nasal cannula oxygen in children with bronchiolitis: A randomized controlled trial.” Pediatric pulmonology (2022). PMID: 35293153 ↗
L1bCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [368]
Sweet SC, Armstrong B, Blatter J et al.. “CTOTC-08: A multicenter randomized controlled trial of rituximab induction to reduce antibody development and improve outcomes in pediatric lung transplant recipients.” American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons (2021). PMID: 34599540 ↗
L1bCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [369]
Roué JM, Delpeut J, d'Hennezel A et al.. “Automatic oxygen flow titration in spontaneously breathing children: An open-label randomized controlled pilot study.” Pediatric pulmonology (2020). PMID: 32827344 ↗
L4Cited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [370]
Vahlkvist S, Jürgensen L, la Cour A et al.. “High flow nasal cannula and continuous positive airway pressure therapy in treatment of viral bronchiolitis: a randomized clinical trial.” European journal of pediatrics (2019). PMID: 31828528 ↗
L1bCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [371]
Yurtseven A, Turan C, Erseven E et al.. “Comparison of heated humidified high-flow nasal cannula flow rates (1-L·kg·min-1 vs 2-L·kg·min -1 ) in the management of acute bronchiolitis.” Pediatric pulmonology (2019). PMID: 30887731 ↗
L1bCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [372]
Conesa-Segura E, Reyes-Dominguez SB, Ríos-Díaz J et al.. “Prolonged slow expiration technique improves recovery from acute bronchiolitis in infants: FIBARRIX randomized controlled trial.” Clinical rehabilitation (2018). PMID: 30442030 ↗
L1bCited in: Acute & Emergency Management: Neonatal Resuscitation & Pediatric Stabilization - [373]
Ukkonen RM, Renko M, Kuitunen I. “Azithromycin for acute bronchiolitis and wheezing episodes in children - a systematic review with meta-analysis.” Pediatric research (2023). PMID: 38066246 ↗
L1aCited in: Long-term & Definitive Management - [374]
Kuitunen I, Renko M. “Inhaled nitric oxide in acute bronchiolitis: A systematic review and meta-analysis.” Pediatric pulmonology (2023). PMID: 37988259 ↗
L1aCited in: Long-term & Definitive Management - [375]
Gutiérrez Moreno M, Del Villar Guerra P, Medina A et al.. “High-Flow Oxygen and Other Noninvasive Respiratory Support Therapies in Bronchiolitis: Systematic Review and Network Meta-Analyses.” Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies (2022). PMID: 36661419 ↗
L1aCited in: Long-term & Definitive Management - [376]
Walker PJ, Wilkes C, Duke T et al.. “Can child pneumonia in low-resource settings be treated without antibiotics? A systematic review & meta-analysis.” Journal of global health (2022). PMID: 36370376 ↗
L1aCited in: Long-term & Definitive Management - [377]
Tejada S, Martinez-Reviejo R, Karakoc HN et al.. “Ribavirin for Treatment of Subjects with Respiratory Syncytial Virus-Related Infection: A Systematic Review and Meta-Analysis.” Advances in therapy (2022). PMID: 35876973 ↗
L1aCited in: Long-term & Definitive Management - [378]
Dafydd C, Saunders BJ, Kotecha SJ et al.. “Efficacy and safety of high flow nasal oxygen for children with bronchiolitis: systematic review and meta-analysis.” BMJ open respiratory research (2021). PMID: 34326153 ↗
L1aCited in: Long-term & Definitive Management - [379]
Quinn LA, Shields MD, Sinha I et al.. “Respiratory syncytial virus prophylaxis for prevention of recurrent childhood wheeze and asthma: a systematic review.” Systematic reviews (2020). PMID: 33239107 ↗
L1aCited in: Long-term & Definitive Management - [380]
Harris J, Crulli B, Latour JM et al.. “Interaction of PEEP and Neurally-Adjusted Ventilatory Assist in Infants With Acute Viral Bronchiolitis.” Respiratory care (2025). PMID: 41163356 ↗
L1bCited in: History and Evolution of Treatment - [381]
Zhao AT, Pirsl F, Parkin J et al.. “Desmosine as a Novel Biomarker Candidate for Pulmonary and Cutaneous Chronic Graft-Versus-Host Disease.” Transplantation and cellular therapy (2026). PMID: 42208939 ↗
L2bCited in: History and Evolution of Treatment - [382]
Astudillo P, López-Lastra M. “Interferon-λ3 rs12979860 polymorphism and early-life RSV-bronchiolitis are associated with persistent asthma in male children: a 4-year prospective follow-up study.” Pediatric research (2026). PMID: 42020794 ↗
L2bCited in: History and Evolution of Treatment - [383]
Razzini JL, Giné-Vázquez I, Jin J et al.. “Impact of universal nirsevimab prophylaxis in infants on hospital and primary care outcomes across two respiratory syncytial virus seasons in Galicia, Spain (NIRSE-GAL): a population-based prospective observational study.” The Lancet. Infectious diseases (2026). PMID: 41539320 ↗
L2bCited in: History and Evolution of Treatment - [384]
Lai YK, Sharifi H, Arai S et al.. “Lung Complications After Allogeneic Hematopoietic Cell Transplant and Outcomes: Implications Beyond Bronchiolitis Obliterans Syndrome.” Transplantation and cellular therapy (2026). PMID: 42259420 ↗
L3bCited in: History and Evolution of Treatment - [385]
Shibata R, Li Y, Yaskolka Meir A et al.. “Nasopharyngeal Microbiome-Epigenome-Wide Association Analysis in Infants With Severe Bronchiolitis.” Allergy (2025). PMID: 41078079 ↗
L2bCited in: Growth, Development & Nutrition Impact - [386]
White BR, Polikoff L, Alexander R et al.. “Acute Respiratory Distress Syndrome in Children With Lower Respiratory Tract Infection Requiring Invasive Mechanical Ventilation: Post Hoc Analysis of the 2019-2020 Bronchiolitis and Codetection Cohort.” Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies (2025). PMID: 40047495 ↗
L2bCited in: Growth, Development & Nutrition Impact - [387]
Rhee C, Hwang JY, Ha JY et al.. “Development and validation of a deep learning-based algorithm for quantifying bronchiolitis obliterans in paediatric computed tomography.” The British journal of radiology (2026). PMID: 41160488 ↗
L3bCited in: Growth, Development & Nutrition Impact - [388]
Kim M, Lee J, Han SB et al.. “Serious bacterial infections in infants younger than 90 days of age with acute bronchiolitis.” European journal of pediatrics (2025). PMID: 40691666 ↗
L3bCited in: Growth, Development & Nutrition Impact - [389]
Zama D, Paccapelo A, Betti L et al.. “The influence of air pollutants on the risk of emergency department presentations of infants with bronchiolitis in an European air quality hotspot.” Pediatric allergy and immunology : official publication of the European Society of Pediatric Allergy and Immunology (2025). PMID: 40171967 ↗
L3bCited in: Growth, Development & Nutrition Impact - [390]
Xu W, Wang H, Wen X et al.. “Risk factors for bronchiolitis obliterans development in children after Mycoplasma pneumoniae pneumonia: a retrospective study of 981 patients.” Italian journal of pediatrics (2025). PMID: 40165275 ↗
L3bCited in: Growth, Development & Nutrition Impact - [391]
Gie A, Le Roux C, van der Zalm MM et al.. “Contribution of post-infectious bronchiolitis obliterans to non-cystic fibrosis bronchiectasis in children.” The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease (2025). PMID: 40155792 ↗
L3bCited in: Growth, Development & Nutrition Impact - [392]
Finnegan K, Smalley J, Gallagher B et al.. “Enteral feeding in pediatric patients with bronchiolitis requiring non-invasive support via nasal interface.” Pediatric research (2025). PMID: 40148473 ↗
L3bCited in: Growth, Development & Nutrition Impact - [393]
Kalantari A, Karimizadeh Z, Behfar M et al.. “Treatment Options for Bronchiolitis Obliterans Secondary to Hematopoietic Cell Transplantation in Children: A Systematic Review.” Clinical transplantation (2025). PMID: 40794819 ↗
L2aCited in: Complications - [394]
Badolato R, Ceconi V, Bellu' R et al.. “Impact of regional heterogeneity of RSV infection prophylaxis on bronchiolitis in Italy.” Italian journal of pediatrics (2026). PMID: 42288825 ↗
L3bCited in: Complications - [395]
Hogan AH, Adams A, Brugge D et al.. “Mapping Bronchiolitis in Connecticut Before and After the COVID-19 Pandemic.” Pediatric pulmonology (2026). PMID: 41457645 ↗
L3bCited in: Complications - [396]
Domany KA, Golan-Tripto I, Burrack N et al.. “Risk factors associated with severe RSV disease among hospitalized children in the second year of life: a multicenter study.” European journal of pediatrics (2025). PMID: 41307723 ↗
L3bCited in: Complications - [397]
Memar EHE, Shirzadi R, Rahsepar NS et al.. “Efficacy and safety of high-flow nasal cannula versus continuous positive airway pressure and conventional oxygen therapies in pediatric acute respiratory failure: a systematic review and meta-analysis.” BMC pediatrics (2026). PMID: 42387462 ↗
L1aCited in: Prognosis & Natural History - [398]
Greiner-Mai M, Rapp CK, Knoflach K et al.. “Telomere biology disorders associated with childhood interstitial lung disease.” Clinical and experimental pediatrics (2026). PMID: 42316340 ↗
L4Cited in: Prognosis & Natural History - [399]
Gotchac J, Rousseau A, Arcourt A et al.. “Point-of-care echocardiographic assessment of right ventricle systolic function in infants with severe bronchiolitis: a prospective observational study.” European journal of pediatrics (2026). PMID: 42498874 ↗
L4Cited in: Special Populations - [400]
Householder S, Harris C, Tarica M et al.. “From Floor to Intensive Care Unit: Unpacking the Real Impact of High-Flow Nasal Cannula on Bronchiolitis Triage.” Hospital pediatrics (2026). PMID: 42481034 ↗
L3bCited in: Special Populations - [401]
Hoyt BM, Thomas J, Tyler A et al.. “Nasogastric Hydration Utilization in Bronchiolitis, an EMO Trial Observational Substudy.” Hospital pediatrics (2026). PMID: 42264484 ↗
L3bCited in: Special Populations - [402]
Yao TC, Hsu YL, Huang JL et al.. “Prenatal and/or childhood acid-suppressive medication use and risk of serious infections in children: A retrospective analysis of Taiwanese medical claims data.” BMC medicine (2026). PMID: 42231258 ↗
L3bCited in: Special Populations - [403]
Buonsenso D, Perramon-Malavez A, Morello R et al.. “How a major discovery can become a public health failure when used subotptimally: lessons from early nirsevimab implementation.” Italian journal of pediatrics (2025). PMID: 41239479 ↗
L2bCited in: Prevention, Screening & Surveillance - [404]
Gower WA, Tamae-Kakazu M, Shanthikumar S et al.. “Pulmonary function testing in pediatric allogeneic stem cell transplant recipients to monitor for Bronchiolitis obliterans syndrome: a systematic review.” BMC pediatrics (2025). PMID: 40155876 ↗
L2aCited in: Prevention, Screening & Surveillance - [405]
Montalti M, Frasca G, Mario SD et al.. “Making regional comparisons policy-ready: clarified, standardised methods and region-wide RSV hospital discharge estimates from Emilia-Romagna, Italy.” Italian journal of pediatrics (2026). PMID: 41963953 ↗
L3bCited in: Prevention, Screening & Surveillance - [406]
Andina Martínez D, Claret Teruel G, Gijón Mediavilla M et al.. “Nirsevimab and Acute Bronchiolitis Admissions in Infants Under One Year of Age.” Pediatric pulmonology (2025). PMID: 40811215 ↗
L3bCited in: Prevention, Screening & Surveillance