(1398) Hypercapnia vs Normocapnia for Post-Cardiac Arrest Patients: A Meta-Analysis of Randomized Trials

Introduction: In post cardiac arrest patients, hypercapnia can increase cerebral blood flow and potentially improve neurological outcomes, as shown in observational studies. However, the randomized controlled trials (RCTs) have reported conflicting results. We conducted a meta-analysis of the RCTs to compile the data.

Methods: We searched electronic databases such as Pubmed, Cochrane, Embase and MEDLINE for the RCTs comparing hypercapnia vs normocapnia in post cardiac arrest patients. The endpoints of interest were mortality and favorable neurological outcomes at the longest available follow up. We performed random effect meta-analysis to estimate odds ratio (OR) with 95% confidence interval (CI). I² statistic was used to define the heterogeneity between the studies.

Results: Three RCTs with a total of 1,871 patients; 930 in the hypercapnia group and 941 in the normocapnia group were included. The mean age was 61 years, 80% of the patients were men and the mean follow up duration was 6 months. There was no significant difference observed between the hypercapnia and normocapnia groups with regards to mortality (427 vs 412, OR 1.13, 95% CI 0.72-1.78, p = 0.60, I² = 44%). Similarly, the favorable neurological outcomes were comparable in the two groups (390 vs 411, OR 0.95, 95% CI 0.67-1.35, p = 0.77, I² = 28%).

Conclusions: In this meta-analysis of RCTs, hypercapnia did not lead to favorable neurological outcomes or reduce mortality when compared with normocapnia in post cardiac arrest patients.