Advantages of bystander-performed conventional cardiopulmonary resuscitation in out-of-hospital cardiac arrest presumably caused by drowning in Japan: a propensity score-matching analysis using an extended nationwide database

Abstract

Objectives This study aimed to determine whether the association between conventional bystander cardiopulmonary resuscitation (BCPR) and better outcomes in drowning-associated out-of-hospital cardiac arrest (OHCA) differs between young and older people or between non-medical and medical drowning in Japan.Design Observational study.Setting This study used data from the Japanese Fire and Disaster Management Agency databases.Participant Of the 504 561 OHCA cases recorded in the nationwide database between 2016 and 2019, 16 376 (3.2%) were presumably caused by drowning.Main outcome measure The main outcomes were a 1-month neurological prognosis defined as cerebral performance category 1 or 2 and 1-month survival as measures.Result The incidence of drowning as a presumed cause of OHCA was high in the winter and the middle-aged and older generations in Japan. However, OHCA caused by drowning in the younger generation frequently occurs in the summer. Furthermore, younger patients had higher incidences of bystander-witnessed cardiac arrest (22.0%), BCPR provision (59.3%) and arrest in outdoor settings (54.0%) than middle-aged and older generations (5.9%, 46.1% and 18.7% respectively). If the patient was younger or the arrest was accidental, the conventional BCPR group had better neurological outcomes than the compression-only BCPR group (95% CI of adjusted OR, 1.22 to 12.2 and 1.80 to 5.57, respectively). However, in the case of middle-aged and older generations and medical categories, there was no significant difference in outcomes between the two types of BCPR. This conventional group’s advantage was maintained even after matching.Conclusion Conventional bystander CPR yielded a higher neurologically favourable survival rate than compression-only BCPR for OHCA caused by drowning if the patient was younger or the arrest was non-medical. Conventional CPR education for citizens who have the chance to witness drownings should be maintained.