Timing of hypothermic temperature control does not affect neurological outcomes after cardiac arrest: a systematic review and meta-analysis
In brief
Starting cooling 97 minutes earlier fails to boost brain recovery after cardiac arrest
A meta-analysis of seven randomized trials (3,288 patients) found that prehospital initiation of hypothermic temperature control reached the target 33 °C about 97 minutes sooner but did not improve the odds of favorable neurological outcome (essentially unchanged). Early cooling was linked to a 30% rise in recurrent arrest and a 60% rise in pulmonary edema, suggesting no benefit and added risk for prehospital use.
- Journal
- Intensive care medicine experimental (Q1)
- Published
- 17 July 2026
- Study design
- Systematic review / meta-analysis of RCTs
- Evidence level
- Level 1, High (CEBM 1a)
- Authors
- Krisztina Csőke-Kabai, Zsolt Molnár, László Zubek, Dávid Laczkó, Caner Turan, Péter Hegyi, et al.
- PMID
- 42467180
- DOI
- 10.1186/s40635-026-00947-9
Why clinicians should know about it
- Picked for Critical Care and Intensive Care Medicine (top studies of the week, 19 July 2026): Hypothermia timing meta‑analysis after cardiac arrest
- Picked for Emergency Medicine (top studies of the week, 19 July 2026).
- Picked for Pulmonary and Respiratory Medicine (top studies of the week, 19 July 2026).
- Picked for Physiology (medical) (top studies of the week, 19 July 2026).
Abstract
Out-of-hospital cardiac arrest is associated with a low rate of favourable neurological recovery, estimated at 8%. Lowering the cerebral metabolic rate with hypothermic temperature control is hypothesized to improve this outcome. Given the importance of temperature control after cardiac arrest, we investigated whether initiating early hypothermic temperature control in the prehospital setting could further enhance neurological recovery. A pre-registered systematic search (PROSPERO: CRD42024601051) was run in PubMed, Embase and Cochrane Central on November 3, 2024 (updated on March 30, 2026) to identify randomised controlled trials that compare prehospital vs. in-hospital initiation of hypothermic temperature control of out-of-hospital cardiac arrest patients. The Cochrane Handbook was followed for data extraction and synthesis. The RoB 2 tool was used for risk of bias assessment. The meta-analyses were conducted using a random-effects model. A total of 7117 articles were screened, and 7 studies including 3288 patients were included in the analysis. The intervention group achieved target temperature of 33 °C significantly earlier (MD: -97.27 min; 95% CI: -139.46 to -55.08; p = 0.010). In the intervention group, no significant difference was observed in the odds for favourable neurological outcome (OR: 0.98; 95% CI: 0.80-1.22, p = 0.855). The rate of recurrent cardiac arrest in the intervention group was significantly higher than in the control group (OR: 1.33; 95% CI: 1.20-1.47; p = 0.009) and the odds for pulmonary oedema were also significantly higher (OR: 1.66; 95% CI: 1.24-2.23; p = 0.001). The results show that despite reaching the target temperature significantly earlier, prehospital initiation of hypothermic temperature control did not improve favourable neurological recovery compared to in-hospital initiation. Furthermore, early initiation also significantly increased the odds for recurrent cardiac arrest and pulmonary oedema. Therefore, these findings do not support the implementation of prehospital hypothermic temperature control in out-of-hospital cardiac arrest, although evidence regarding fluid-sparing approaches such as transnasal evaporative cooling remains limited.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.