Literature Review: AHA Guidelines and Cardiac Arrest Survival

   Hinchey PR, Myers JB, Lewis R, et al. Improved out-of-hospital cardiac arrest survival after the sequential implementation of 2005 AHA guidelines for compressions, ventilations and induced hypothermia: The Wake County experience. Ann Emerg Med, Mar 30, 2010 [E-pub ahead of print].

Abstract

   Objective—To assess survival from out-of-hospital cardiac arrest after community-wide implementation of 2005 American Heart Association guidelines. Methods—This was an observational multiphase before-after cohort in an urban/suburban community (population 840,000) with existing advanced life support. Included were all adults treated for cardiac arrest by emergency responders. Excluded were patients younger than 16 years and trauma patients. Intervention phases in months were baseline, 16; phase 1, new cardiopulmonary resuscitation, 12; phase 2, impedance threshold device, 6; and phase 3, full implementation including out-of-hospital-induced hypothermia, 12. Primary outcome was survival to discharge. Other survival and neurologic outcomes were compared between study phases, and adjusted odds ratios with 95% confidence intervals for survival by phase were determined by multivariate regression.

   Results—One thousand, three hundred sixty-five cardiac arrest patients were eligible for inclusion: baseline, n=425; phase 1, n=369; phase 2, n=161; phase 3, n=410. Across phases, patients had similar demographic, clinical and emergency medical services characteristics. Overall and witnessed ventricular fibrillation and ventricular tachycardia survival improved throughout the study phases: respectively, baseline, 4.2% and 13.8%; phase 1, 7.3% and 23.9%; phase 2, 8.1% and 34.6%; and phase 3, 11.5% and 40.8%. The absolute increase for overall survival from baseline to full implementation was 7.3%; witnessed ventricular fibrillation/ventricular tachycardia survival was 27.0%, representing an additional 25 lives saved annually in this community.

   Conclusion—In the context of a community-wide focus on resuscitation, the sequential implementation of 2005 American Heart Association guidelines for compressions, ventilations and induced hypothermia significantly improved survival after cardiac arrest. Further study is required to clarify the relative contribution of each intervention to improved survival outcomes.

Comment

   This excellent study makes three important points: 1) It's the basics that increase survival: quality of chest compressions and ventilations, along with therapeutic hypothermia; 2) "good neurological recovery" can be measured and improved with advances in prehospital care; and 3) a careful QI approach can be used to examine the effect of system changes—and benefit the entire community. These authors built upon the work of previous studies (which showed, for example, that minimizing interruptions in chest compressions or reducing ventilation rates was beneficial) and introduced them into a real-world setting using a coordinated, stepwise systemwide approach. Most important, they used Cerebral Performance Category 1 (full recovery) or 2 (capable of independent activities of daily living) as the desired endpoint—a measure far more valuable than ROSC, survival to hospital admission or even survival to hospital discharge.

   This study should be used as a template for EMS systems looking to improve their cardiac arrest care. The model of introducing systemwide changes in care and measuring the results using meaningful outcomes (here, neurologically intact survival to hospital discharge) should be the goal of all EMS systems.

   Angelo Salvucci, Jr., MD, FACEP, is medical director for the Santa Barbara County and Ventura County (CA) EMS agencies.