There is growing evidence that early detection and response to physiological deterioration can improve outcomes for hospitalized infants, children, and adults. A rapid response system (RRS) is a multidisciplinary system to decrease the incidence of in-hospital cardiopulmonary arrests by detecting a crisis event and triggering a response and by dispatching a responding team. For quality improvement of the system, a review mechanism is vital to identify opportunities for preventing future events or improving response after crises occur. The whole system requires an administrative component that oversees the RRS and provides support. The system is designed to locate and respond rapidly to a suddenly critically ill patient who lacks necessary critical care resources. Over the past decade, RRSs have been widely implemented in adult practice in the United States, Canada, Australia, the United Kingdom, and Scandinavian countries.