253 Trends in Out-of-Hospital Cardiac Arrests in Los Angeles

Abstract

The aim of this study was to evaluate the characteristics and outcomes of out-of-hospital cardiac arrests (OOHCA) in order to determine the potential impact of changes in CPR and advanced cardiac life support (ACLS) protocols. This was a retrospective cohort study which included all adult (age >18), non-traumatic out-of-hospital cardiac arrest patients in the City of Los Angeles from 2003 through 2010, upon whom paramedics initiated resuscitative efforts. We determined the annual number of cardiac arrests, the incidence of primary ventricular fibrillation, the rate of return of spontaneous circulation, and the frequency where paramedics terminated resuscitative (TOR) efforts on scene through on-line medical control. All Los Angeles Fire Department EMTs and paramedics were trained in 2006 on the 2005 CPR/ACLS Guidelines, which emphasized the importance of quality CPR, avoiding hyperventilation, and remaining on scene for longer periods of time prior to hospital transport. During the study period there were 11,395 OOHCA. The incidence of primary ventricular fibrillation steadily declined from 21.2 % in 2003 to 17.7 % in 2010 (p =0.07). The rate of return of spontaneous circulation for all patients increased from 14.0% to 30.2% (p<0.0001); the rate of return of spontaneous circulation for witnessed ventricular fibrillation increased from 25.6% to 46.6% (p=0.009); and the rate of TOR increased from 17.7% to 30.2% (p<0.0001). Despite a decline in the incidence of primary ventricular fibrillation, the rate of return of spontaneous circulation increased significantly while the rate of termination of resuscitative efforts on scene also increased significantly. Attention to quality CPR, providing adequate time for out-of-hospital interventions on scene, and avoiding unnecessary transports of unsuccessful resuscitative efforts are essential in improving the outcome from OOHCA. Further study is needed to determine ultimate patient survival to hospital discharge.