Bystander CPR is associated with improved neurologically favourable survival in cardiac arrest following drowning

Cardiac arrest associated with drowning is a major public health concern with limited research available on outcome. This investigation aims to define the population at risk, and identify factors associated with neurologically favourable survival.

The Cardiac Arrest Registry for Enhanced Survival (CARES) database was queried for patients who had suffered cardiac arrest following drowning between January 1, 2013 and December 31, 2015. The primary outcomes of interest were for favourable or unfavourable neurological outcome at hospital discharge, as defined by Cerebral Performance Category (CPC).

A total of 919 drowning patients were identified. Neurological outcome data was available in 908 patients. Neurologically favourable survival was significantly associated with bystander CPR (Odds Ratio (OR)=2.94; 95% Confidence Interval (CI) 1.86-4.64; p<0.001), witnessed drowning (OR=2.6; 95% CI 1.69-4.01; p<0.001) and younger age (OR=0.97, 95% CI 0.96-0.98; p<0.001). Public location of drowning (OR=1.17; 95% CI 0.77-1.79; p=0.47), male gender (OR=0.9, 95% CI 0.57-1.43; p=0.66), and shockable rhythm (OR=1.54; 95% CI 0.76-3.12; p=0.23), were not associated with favourable neurological survival. AED application prior to EMS was associated with a decreased likelihood of favourable neurological outcome (OR=0.38; 95% CI 0.28-0.66; p<0.001). In multivariate analysis, bystander CPR (adjusted OR 3.02, 95% CI 1.85-4.92, p<0.001), witnessed drowning (adjusted OR 3.27, 95% CI 2.0-5.36, p<0.001) and younger age (adjusted OR 0.97, 95% CI 0.96-0.98, p<0.001) remained associated with neurologically favourable survival.

Neurologically favourable survival after drowning remains low but is improved by bystander CPR. Shockable rhythms were uncommon and not associated with improved outcomes.