Takayama W, et al. – In this study, researchers investigated cardiopulmonary resuscitation (CPR) parameters according to time period based on in-hospital cardiopulmonary resuscitation (IHCPR) duration and the frequency of iatrogenic chest injuries among out-of-hospital cardiac arrest (OHCA) patients. They evaluated 1,254 non-traumatic OHCA patients (day-time: 948, night-time: 306) who were transferred between 2013 and 2016 in this two-center, observational, cohort study. The night-time patients were noted to have a significantly shorter IHCPR duration (27.8 minutes vs 23.6 minutes), a higher incidence of chest injuries (40.4% vs 67.0%), and a lower rate of return of spontaneous circulation (38.4% vs 26.5%). The rates of survival to emergency department and hospital discharge were not significantly different. These findings suggested a higher risk for CPR-related chest injury among patients who underwent night-time treatment for OHCA despite their shorter resuscitation duration.