Time to first defibrillation attempt in pediatric patients who had an in-hospital cardiac arrest (IHCA) was not associated with survival or other major outcomes, according to an observational study of a large, multicenter cohort.
The results are in contrast to established data and guidelines for adults, noted Elizabeth A. Hunt, MD, MPH, PhD, of Johns Hopkins Charlotte Bloomberg Children’s Center in Baltimore, and colleagues.
The study, published online in JAMA Network Open, showed that in 477 children with IHCA with a first documented shockable rhythm, the median time to first defibrillation attempt was 1 minute (range of 0-3 minutes) in both survivors and nonsurvivors – 71% of events received a first defibrillation attempt in 2 minutes or less, and the overall rate of survival to discharge was 38%.
“Contrary to our hypothesis, we did not find a significant association between time elapsed from loss of pulse to first defibrillation attempt and survival to hospital discharge [after adjusting for numerous covariates] (RR 0.99; 95% CI 0.94-1.06, P=.86),” Hunt and co-authors wrote.
They cited data from large animal laboratory models, studies of adult cardiac arrest — both out-of-hospital [OHCA] and in-hospital, and pediatric OHCA — that have linked the time to first defibrillation attempt for pulseless ventricular tachycardia and ventricular fibrillation with survival. “It is important to explore what may be unique about pediatric IHCA and the implications for future research and clinical approach,” the team wrote.
Approximately 6,000 children in the U.S. have an IHCA each year, and while survival has improved over the last decade, care processes and outcomes vary considerably. “Although many IHCAs in children have a noncardiac origin, 10-15% have a first documented rhythm that requires defibrillation.”
For the study, the researchers analyzed data collected between January 1, 2000, and December 31, 2015 from the Get With The Guidelines–Resuscitation national registry of IHCA patients younger than 18 with a first documented rhythm of pulseless ventricular tachycardia or ventricular fibrillation and at least one defibrillation attempt.
Analyses included 477 patients from the registry of over 17,700 pediatric patients with IHCA, after exclusion of patients who received CPR for bradycardia, pulseless electrical activity, or asystole, or had incomplete data. Median age was 4, and 60% were male.
Children were less likely to be shocked in 2 minutes or less when cardiac arrest occurred on the wards compared with in intensive care units (ICUs) (48% versus 72%; P=.01), although the majority of events occurred in ICU, the team reported.
Time to first defibrillation attempt was not associated with survival in unadjusted analysis (RR per minute increase, 0.96; P = .15) or adjusted analysis (RR, 0.99; P = .86). Having a first defibrillation attempt in 2 minutes or less compared with more than 2 minutes did not affect survival in unadjusted analysis (RR, 0.87; P = .29) or multivariable analysis (RR, 0.99; P = .93).
Similarly, time to first defibrillation attempt had no impact on secondary outcomes, which included return of circulation, 24-hour survival, and favorable neurologic outcome at hospital discharge.
Study limitations noted by the authors included the small sample size, that the chaotic environment surrounding cardiac arrest may have led to some misclassification of time and other variables, and that most first defibrillation attempts occurred within 2 minutes of loss of pulse.
In attempting to explain the unexpected findings, Hunt and colleagues suggested that the time to first defibrillation attempt does not in fact affect survival to discharge, that the ability to alter IHCA outcome with time to first defibrillation attempt is not demonstrable in a child who is critically ill, and that the study‘s small sample size and misclassification may obscure the association.
In an accompanying editorial, Alexis Topjian, MD, MSCE, of Children’s Hospital of Philadelphia, proposed several reasons for the unexpected findings – that the majority of cardiac arrests occurred in the ICU and were witnessed and monitored; that based on Pediatric Advanced Life Support guideline recommendations, most of these patients likely received CPR prior to defibrillation, thus increasing optimal blood flow to the myocardium and improving defibrillation success — a benefit that would be reduced in adults — with cardiac arrest due to coronary artery disease, since narrowing of the coronary arteries can decrease myocardial perfusion.
This supports the concept of rapid recognition, prompt chest compressions, and defibrillation as soon as possible, Topjian wrote. “The most impressive findings in this study are that 73% of children achieved return of circulation and 38% survived to discharge. “
Hunt and some co-authors reported financial relationships with Zoll Medical Corporation.
Topjian reported having no conflicts of interest.