Oxygen and carbon dioxide targets after cardiac arrest: an updated systematic review

Aim

To perform an updated systematic review and meta-analysis of oxygen and carbon dioxide targets in patients with sustained return of spontaneous circulation after cardiac arrest.

Methods

Searches were conducted in MEDLINE, Embase, and Evidence-Based Medicine Reviews from August 2019 to March 2025 for randomised trials comparing specific oxygen or carbon dioxide targets in post-cardiac arrest patients. Two investigators independently reviewed trials for relevance, extracted data, and assessed risk of bias. Data were pooled using random-effects models. The certainty of evidence was evaluated using GRADE methodology.

Results

Fifteen manuscripts from 12 trials were included. All trials were limited to adult patients, primarily including out-of-hospital cardiac arrests. Five trials evaluated oxygen targets in the prehospital setting, while six evaluated oxygen targets and three evaluated carbon dioxide targets in the intensive care unit setting. Risk of bias was assessed as moderate for most outcomes. Meta-analyses found no differences in survival or favourable functional outcomes when comparing restrictive to liberal oxygen targets in either setting. There was also no difference in outcomes when comparing mild hypercapnia to normocapnia. The certainty of evidence was rated as low to moderate.

Conclusions

Among patients resuscitated from cardiac arrest, neither restrictive oxygen targets nor mild hypercapnia, compared to conventional targets, improved survival or functional outcomes.