Lee JH, et al. - Whether counting inflation breaths out loud during cardiopulmonary resuscitation (CPR) led to an earlier resumption of chest compressions was examined in this randomised controlled manikin simulation study. From February 2015 to April 2015, 32 fourth-year Korean medical students, equally divided into study and control groups, performed 10 cycles of 15:2 CPR while administering inflation breaths using a bag mask. The findings demonstrated that counting the number of inflation breaths out loud was a simple method that improved the speed of resuming chest compressions and increased chest compression fractions (CCFs) in 15:2 CPR.