Characteristics and outcomes of out-of-hospital cardiac arrest due to drowning - a nationwide registry-based study.

Abstract

Aim of the study: To describe and compare cases of resuscitation after out-of-hospital cardiac arrest (OHCA) attributed to drowning (D-OHCA) versus other causes (ND-OHCA).

Methods: Retrospective, descriptive and comparative analysis of D-OHCA vs. ND-OHCA patients registered in the German Resuscitation Registry from January 2013 to December 2023 using Chi-square, Mann-Whitney U tests and regression analysis. Key variables included 10-year age groups, body temperature measured at the scene, prehospital factors (e.g., bystander CPR, initial rhythm), and outcomes such as survival and neurological status (CPC, mRS) at hospital discharge.

Results: Of the 68,719 included patients 316 (0.5%) had D-OHCA with 50% of the cases occurring during the summer months (June, July and August). D-OHCA in comparison to ND-OHCA patients were younger (median age 50 years vs. 72.5 years, p < 0.001), had a higher rate of asystole as initial rhythm (73.1 vs. 54.9%, p < 0.001) and a lower initial body temperature (median of 31.1 °C vs. 35.8 °C, p < 0.001). While overall survival and favourable neurological outcomes did not differ significantly between groups, stratified analysis showed that D-OHCA patients aged 0-10 years had significantly higher survival rates (44.7% vs. 16.3%, p < 0.001) and favourable neurological outcomes at hospital discharge (34.0% vs. 7.6%, p < 0.001) compared to ND-OHCA patients under 11 years.

Conclusion: Drowning was a rare cause of out-of-hospital cardiac arrest in this study, often occurring during summer months. Outcome in D-OHCA was generally comparable to ND-OHCA and only better in children aged up to 10 years. Lower body temperatures were associated with unfavourable outcomes in most D-OHCA cases.