Review Of: Kudenchuk P, Redshaw J, Stubbs B, et al. Impact of changes in resuscitation practice on survival and neurological outcome after out-of-hospital cardiac arrest resulting from non-shockable arrhythmias.Circulation. 2012;125(14):1787–1794.
The Science: This is a comprehensive observational study of non-shockable cardiac arrest patients in King County, Wash. Investigators compared 2,000 American Heart Association (AHA) cardiac arrest guidelines (patients in the control group) to 2005 AHA cardiac arrest guidelines (patients in the study group) and the impact on non-shockable cardiac arrest survival with the primary endpoint being survival to one year. Several other outcomes were also measured: return of spontaneous circulation (ROSC), neurological outcome, and survival to one month. Investigators found that, after adjusting for other variables that could affect data, all were significantly associated with overall improved outcomes in the study group.
Dr. Wesley: The authors of this study are some of the premier researchers in out-of-hospital cardiac arrest. This paper is one of the first to indicate that the changes in the AHA guidelines are improving care. In this case, the 2000 guidelines were compared with the 2005 guidelines, and their affect on non-shockable arrests was analyzed.
The most significant change in the two guidelines is the emphasis on high quality chest compressions with minimal interruptions, which is also emphasized in the 2010 guidelines. This study is important because it specifically examines the non-shockable arrest—those in asystole or pulseless electrical activity (PEA.)
The primary reason to examine this subset of cardiac arrest is that non-shockable rhythms are currently the most common presentation of out-of-hospital cardiac arrest. We have excellent data that proves that the key to survival for shockable arrests is bystander CPR, high quality CPR, and rapid delivery of defibrillation.
To date, little attention has been paid to what is now the more common presentation of cardiac arrest. We have traditionally considered non-shockable arrests to be futile. Although their survival rates are significantly lower than those rates for shockable arrests, it’s time for us to determine what, if any, interventions may positively affect them. This study would indicate that high quality CPR improves outcomes for this group. The next step is to determine whether there are additional interventions, such as reversal of metabolic acidosis and administration of vasopressors.
Medic Marshall: This study does two things for me. First, it shows me we’re heading down the right path in cardiac arrest management with emphasis on chest compressions and circulation of blood. But on the flip side, it shows me that we still have a long way to go to ensure we all take some responsibility in out-of-hospital cardiac arrest.
The wonderful thing about King County, which is actually highlighted in the paper, notes the maturity of its EMS system. I believe this contributes to some of the success they experience regarding cardiac arrest outcomes. King County has always seemed to be on the forefront of cardiac arrest management with its excellent training and education, a high percentage of a community trained in CPR, and a robust EMS system overall. I firmly believe a study of this caliber could only have been completed in a few select areas around the country.
Cardiac arrest survival across the country continues to vary greatly. As services like King County continue to be a benchmark EMS service, the variability in types of services, quality of care, and failures to adopt evidence-based practices leads me to believe we’re not going to be seeing universal results across the country any time soon.
Background: Out-of-hospital cardiac arrest (OHCA) claims millions of lives worldwide each year. OHCA survival from shockable arrhythmias (ventricular fibrillation/tachycardia) improved in several communities after implementing American Heart Association resuscitation guidelines that eliminated “stacked” shocks and emphasized chest compressions. “Non-shockable” rhythms are now the predominant presentation of OHCA, upon which the benefit of such treatments is uncertain.
Methods & Results: We studied 3,960 patients with non-traumatic OHCA from non-shockable initial rhythms treated by prehospital providers in King County, Wash., over a 10-year period. Outcomes during a 5 year intervention period after adoption of new resuscitation guidelines were compared to the previous 5 year historical control period. The primary outcome was 1-year survival. Patient demographics and resuscitation characteristics were similar between control (n=1774) and intervention (n=2186) groups, among whom 471/1774 (27%) versus 742/2186 patients (34%), respectively, achieved return of circulation (ROSC); 82 (4.6%) versus 149 (6.8%) were discharged from hospital, 60 (3.4%) versus 112 (5.1%) with favorable neurological outcome; 73 (4.1%) versus 135 (6.2%) survived 1-month, and 48 (2.7%) versus 106 patients (4.9%) survived 1-year; all p<0.005. After adjusting for potential confounders, the intervention period was associated with an improved odds of 1.50 (95% confidence interval (CI) 1.29, 1.74) for ROSC; 1.53 (CI 1.14, 2.05) for hospital survival, 1.56 (CI 1.11, 2.18) for favorable neurological status; 1.54 (CI 1.14, 2.10) for 1-month survival, and 1.85 (CI 1.29, 2.66) for 1-year survival.
Conclusions: Outcomes from OHCA due to non-shockable rhythms, though poor by comparison with shockable rhythm presentations, improved significantly after implementing resuscitation guideline changes, suggesting their potential to benefit all presentations of OHCA.