Survival models for out-of-hospital cardiopulmonary resuscitation from theperspectives of the bystander, the first responder, and the paramedic

Survival from out-of-hospital resuscitation depends on the strength of each component of the chain of survival. We studied, on the scene, witnessed, n ontraumatic resuscitations of patients older than 17 years. The influence o f the chain of survival and potential predictors on survival was analyzed b y logistic regression modeling. From 1030 patients, 139 survived to hospita l discharge. Three prediction models of survival were developed from the pe rspective of the different contributors active in out-of-hospital resuscita tion: model I, bystanders; model II, first responders; and model Ill, param edics. Predictors for survival (with odds ratio) were: in model I (bystande rs): emergency medical service (EMS) witnessed arrest (0.50), delay to basi c cardiopulmonary resuscitation (CPR) (0.74/min) and delay to EMS arrival ( 0.87/min); in model II (first responders): initial recorded heart rhythm (0 .02 for nonshockable rhythm), delay to basic CPR (0.71/min and 0.87/min for shockable and nonshockable rhythms) and to defibrillation (0.83/min), and in model III (paramedics): need for advanced CPR (4.74 for advanced CPR not -needed), initial recorded heart rhythm (0.05 for nonshockable rhythm), and delay to basic CPR (0.77/min and 0.72/min for shockable and nonshockable r hythms), to defibrillation and to advanced CPR for shockable rhythms (0.89/ min), and to advanced CPR for nonshockable rhythm (0.85/min). The area unde r the receiver-operator characteristic curve for model I was 0.763, for mod el Il was 0.848, and for model III was 0.896. Of survivors, 50% had restora tion of circulation without need for advanced CPR. Three survival models fo r witnessed nontraumatic out-of-hospital resuscitation based on the informa tion known by bystanders, first responders and paramedics explained surviva l with increasing precision. Early defibrillation can restore circulation w ithout the need for advanced CPR. When advanced CPR is needed, its delay le ads to a markedly reduced survival. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.