Abstract Or113: Rescue Breathing Makes a Difference: Superior Neurological Outcomes with Conventional CPR in Drowning-Related Cardiac Arrest

Introduction: The effectiveness of compression-only cardiopulmonary resuscitation (CPR) has been well-documented in cardiac-origin out-of-hospital cardiac arrest (OHCA). However, for non-cardiac etiologies such as drowning, conventional CPR with rescue breathing is recommended in guidelines based primarily on expert opinion, with limited evidence supporting its superiority. Objectives: To evaluate the association between bystander CPR type and neurologically favorable survival in drowning-related OHCA. Methods: This retrospective observational study analyzed nationwide Utstein data from Japan between 2013 and 2021. Drowning-related OHCA patients were categorized into three groups: no bystander CPR, compression-only CPR, and conventional CPR. The primary outcome was neurologically favorable survival at 30 days. Multivariable logistic regression with Firth's bias reduction method was used to adjust for potential confounders including year, gender, age, physician presence, witness status, public-access defibrillation, initial rhythm, airway management, adrenaline administration, and time intervals. Results: Among 29,680 drowning-related OHCA patients, 52.6% received no bystander CPR, 41.7% received compression-only CPR, and 5.6% received conventional CPR. Unadjusted rates of neurologically favorable survival were 0.31%, 2.01%, and 10.43%, respectively. After adjustment for confounders, both compression-only CPR (adjusted odds ratio [AOR]: 3.30, 95% CI: 2.31-4.72, p<0.001) and conventional CPR (AOR: 6.45, 95% CI: 4.19-9.93, p<0.001) were associated with significantly higher odds of neurologically favorable survival compared to no bystander CPR. Conventional CPR showed significantly better outcomes compared to compression-only CPR (AOR: 1.95, p<0.001). Adjusted predicted probabilities were 0.09% (95% CI: 0.06-0.12%) for no bystander CPR, 0.28% (95% CI: 0.21-0.37%) for compression-only CPR, and 0.55% (95% CI: 0.38-0.81%) for conventional CPR. Conclusions: In drowning-related OHCA, both types of bystander CPR were associated with improved neurologically favorable survival. However, conventional CPR with rescue breathing resulted in significantly better outcomes than compression-only CPR. These findings support current guideline recommendations for conventional CPR in drowning-related cardiac arrest.