Oxygen targets following cardiac arrest: A meta-analysis of randomized controlled trials

The appropriate oxygen target post-resuscitation in out-of-hospital cardiac arrest (OHCA) patients is uncertain. We sought to compare lower versus higher oxygen targets in patients following OHCA.

We searched MEDLINE, Embase, the Cochrane Library, and ClinicalTrials.gov until January 2023 to include all randomized controlled trials (RCTs) that evaluated conservative vs. liberal oxygen therapy in OHCA patients. Our primary outcome was all-cause mortality at 90 days while our secondary outcomes were the level of neuron-specific enolase (NSE) at 48 h, ICU length of stay (LOS), and favorable neurological outcome (the proportion of patients with Cerebral Performance Category scores of 1-2 at end of follow-up). We used RevMan 5.4 to pool risk ratios (RRs) and mean differences (MDs).

Nine trials with 1971 patients were included in our review. There was no significant difference between the conservative and liberal oxygen target groups regarding the rate of all-cause mortality (RR 0.95, 95% CI: 0.80 to 1.13; I² = 55%). There were no significant differences between the two groups when assessing favorable neurological outcome (RR 1.01, 95% CI: 0.92 to 1.10; I² = 4%), NSE at 48 h (MD 0.04, 95% CI: -0.67 to 0.76; I² = 0%), and ICU length of stay (MD -2.86 days, 95% CI: -8.00 to 2.29 days; I² = 0%).

Conservative oxygen therapy did not decrease mortality, improve neurologic recovery, or decrease ICU LOS as compared to a liberal oxygen regimen. Future large-scale RCTs comparing homogenous oxygen targets are needed to confirm these findings.