Quick Defibrillation Not Tied to Better Survival in Hospitalized Kids With Cardiac Arrest

Veronica Hackethal, MD

September 25, 2018

Earlier time to first defibrillation in children with an in-hospital cardiac arrest is not linked to increased survival to discharge, according to a study published online September 21 in JAMA Network Open.

The study also found that time to first shock was not linked to improved 24-hour survival, return of circulation, or favorable neurological outcomes.

"Contrary to published adult [in-hospital cardiac arrest] and pediatric [out-of-hospital cardiac arrest] data, we did not observe a significant association between time to first defibrillation attempt and survival to hospital discharge," write Elizabeth Hunt, MD, MPH, from Johns Hopkins University in Baltimore, Maryland, and colleagues with the American Heart Association's Get With The Guidelines–Resuscitation Investigators.

About 6000 children in the United States experience an in-hospital cardiac arrest each year, and about 10% to 15% of these children have a cardiac rhythm requiring defibrillation. Since 1977, guidelines have recommended early defibrillation in pediatric cardiac arrest. Current European and American Heart Association guidelines continue to recommend early defibrillation in children.

Although delayed defibrillation in adults has been linked to decreased survival, no large population studies have evaluated the issue in children.

To see how time to first defibrillation affects outcomes in children, researchers conducted an observational cohort study using data from the Get With the Guidelines–Resuscitation national registry. The registry is sponsored by the American Heart Association, with the aim of improving outcomes after in-hospital cardiac arrest.

The analysis included 477 children younger than 18 years (median age, 4 years; 60% boys) who experienced an in-hospital cardiac arrest in one of 113 hospitals between January 2000 and December 2015. Included children experienced a shockable rhythm (pulseless ventricular tachycardia or ventricular fibrillation) and at least one attempt at defibrillation.

The primary outcome was survival to hospital discharge. Results were adjusted for age, sex, type of illness, preexisting conditions, location within the hospital, and time of cardiac arrest, as well as hospital and cardiac arrest characteristics.

Seventy-one percent of included children had a first defibrillation attempt within 2 minutes of loss of pulse, with a median time to first attempt of 1 minute. Children in intensive care were significantly more likely to be shocked within 2 minutes or less compared with children hospitalized on wards (72% vs 48%; P = .01). Overall, 38% of children survived to hospital discharge.

Children who received first defibrillation in 2 minutes or less showed no difference in survival compared with those for whom defibrillation was delayed more than 2 minutes (adjusted relative risk [aRR], 0.99; 95% confidence interval [CI], 0.75 - 1.30; P = .93).

In addition, time to defibrillation was not linked to return of circulation (aRR per minute increase, 0.99; 95% CI, 0.98 - 1.01; P = .42), 24-hour survival (aRR per minute increase, 0.99; 95% CI, 0.96 - 1.01; P = .37), or favorable neurologic outcomes (aRR per minute increase, 0.98; 95% CI, 0.90 - 1.07; P = .68).

"The lack of association between earlier time to first defibrillation attempt and survival is difficult to fully understand," writes Alexis Topjian, MD, MSCE. in an accompanying commentary.

The authors provided several possible explanations, but also acknowledge that they do not have a single explanation for these results. However, it seems likely that children who experience in-hospital cardiac arrests are different from adults, according to Topjian.

In this study, 78% of pediatric cardiac arrests happened in the intensive care unit, whereas most adult cardiac arrests occur on the wards. As a result, 96% of children were highly monitored, 97% of cardiac arrests were witnessed, and most had near immediate cardiopulmonary resuscitation, which may have kept the heart muscle perfused. Also, cardiac arrest may be different in critically ill children than in adults, for whom coronary artery disease causes most cardiac arrest.

Topjian points to one additional issue: the study may have been too small, and some cardiac events or time to first defibrillation may have been incorrectly recorded in the chart, which could have biased results.

However, Topjian stresses that the importance of this study lays in highlighting recent improvements in pediatric resuscitation. "Over the last 2 decades, survival from pediatric [in-hospital cardiac arrest] has increased from 14% to 39% without an increase in neurologic morbidity," Topjian notes.

"While pediatric and adult cardiac arrest differ in both epidemiology and pathophysiology, the lack of difference in survival to discharge attributable to defibrillation in this study is far from final," he concluded. "In fact, the most impressive findings in this study are that 73% of children achieved return of circulation and 38% survived to discharge."

One or more authors reports receiving grants, honoraria, reimbursement, travel expenses, and/or personal fees from one or more of the following: the National Institutes of Health, Zoll Medical Corporation, and/or the National Heart, Lung, and Blood Institute during the conduct of the study. In addition, two study authors have patents on educational technology for which Zoll Medical Corporation has a nonexclusive license. Topjian has disclosed no relevant financial relationships.

JAMA Network Open. 2018;1(5):e182643, e182653. Article full text, Editorial full text

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