Chest-compression-only bystander cardiopulmonary resuscitation in the 30:2 compression-to-ventilation ratio era. Nationwide observational study.

BACKGROUND: The compression-to-ventilation ratio for basic cardiopulmonary resuscitation (CPR) was changed from 15:2 to 30:2, but there are few human studies comparing chest-compression-only CPR with standard CPR.

METHODS AND RESULTS: From the All-Japan Utstein Registry in the 30:2 CPR era, 173,565 adult cardiac arrests witnessed by bystanders were included. On arrival at the scene, emergency medical services responders assessed the status of dispatcher-assisted CPR instruction and bystander CPR technique (chest compression with or without rescue breathing). The primary endpoint was favorable neurological outcome 30 days after cardiac arrest. The prevalence of dispatcher-assisted CPR instruction increased year by year, contributing to an overall increase of chest-compression-only bystander CPR from 20.6% to 35.0%. Among 78,150 patients receiving bystander CPR, favorable neurological outcome did not differ between dispatcher-assisted and -unassisted CPR (adjusted odds ratio [OR], 1.00; 95% confidence interval [CI]: 0.94-1.08). Chest-compression-only CPR resulted in better favorable neurological outcome than standard CPR in the whole cohort (adjusted OR, 1.09; 95% CI: 1.00-1.18) and in the subgroup with cardiac etiology (adjusted OR, 1.12; 95% CI: 1.02-1.22). The addition of rescue breathing provided no neurological benefit in the non-cardiac etiology subgroup.

CONCLUSIONS: In the 30:2 CPR era, dispatcher-assisted CPR instruction contributed to an increase of chest-compression-only bystander CPR, supporting the use of chest-compression-only CPR for bystander-witnessed out-of-hospital cardiac arrest in all adults.