Outcome analysis in EMS systems

Abstract

See related article, p 1258. Enormous advances in the structure and sophistication of emergency medical services (EMS) systems have occurred during the past two decades. However, little is known about the effect of prehospital interventions on patient outcome. Despite a plethora of EMS research, only two specific interventions have been proven to impact outcome in any prehospital patient population (early CPR and early defibrillation in the setting of out-of-hospital, nontraumatic cardiac arrest). Given the expense and complexity of establishing and maintaining prehospital care systems, it has become clear that the single most important current need in EMS is the proper scientific evaluation of the impact of prehospital interventions on patient outcome. In this issue, Lindbeck and associates deal with such an issue. In their evaluation of victims of out-ofhospital, nontraumatic cardiac arrest transported by helicopter, they report a 1% survival to hospital discharge. In this survivor, successful resuscitation already had been accomplished by ground-based advanced life support (ALS) personnel before the arrival of the helicopter. This finding has led to an alteration in the use of air medical resources for this problem within their system. Under certain circumstances, it appears that the use of air medical resources will have improved efficiency with a very low risk for withholding a potentially beneficial intervention. For this, the authors are to be applauded. How this investigation ought to affect the use of air medical resources in other EMS systems, however, should not follow immediately from these data. Attempting to interpret how prehospital outcome studies in one system should impact others is an important but precarious pathway. This is highlighted by the fact that the patient population in this study had an expected probability of survival of essentially zero regardless of what interventions occurred. This is so