The survival rates of IHCA remain consistent among day, afternoon, and night in our study. A previous large database study in the United States showed the survival rates were substantially lower during nights and weekends in the ward setting,18 due to fewer health care professionals being present and available at night to respond to a cardiac arrest. In the ED, there is no circadian difference among mortality rates due to sufficient medical staff and experienced attending physicians being available at all times. A prolonged length of stay in ED had an adverse effect in trauma,18 sepsis,19 cardiovascular disease,20 and 21 and acute stroke.22 In our study, there was no survival advantage in different lengths of stay, which is also probably due to the high quality of patient care before arrest and the adequate response in resuscitation in the hospital setting of the study.