(Reuters Health) - Older children in cardiac arrest are more likely than younger kids to have a bystander use a defibrillator to treat them before an ambulance arrives, a U.S. study suggests.

The study focused on 1,400 cardiac arrests in kids ranging in age from 2 to 18 years. Most of these cases, 75 percent, happened in private places and 63 percent were not witnessed by other people who might have been able to treat kids with an automated external defibrillator (AED).

Overall, bystanders used AEDs before ambulances arrived in just 28 percent of cases. The vast majority of these incidents involved first responders like lifeguards or police officers who deployed AEDs before ambulances reached the scene.

“As we suspected, AED use in the pediatric population is low,” said senior study author Dr. Peter Aziz, a heart rhythm specialist at Cleveland Clinic Children’s in Ohio.

In cardiac arrest, the heart stops abruptly, often due to irregular heart rhythms. Cardiac arrest may occur with no warning and is fatal unless the heart can be restarted quickly. In about 25 percent of cardiac arrests that occur outside of hospitals, the irregular rhythm is potentially shockable, meaning it’s possible the heart can be restarted with electic shocks.

Automated defibrillators are often available in public places like restaurants and airports. These devices typically have electrodes that attach to the chest with sticky pads and deliver shocks based on what a computer in the defibrillator determines the person needs.

Specially made pads for kids deliver less energy and are recommended for younger and smaller patients - typically children under 8 years old or weighing less than 55 pounds (24.95 kg). But bystanders should use adult pads on children when pediatric pads aren’t available, Aziz said by email.

Not surprisingly, children who went into cardiac arrest in a public location were almost twice as likely to have a bystander use a defibrillator compared with kids whose arrest happened in homes or other private locations, researchers report in Pediatrics.

Older children were also 50 percent more likely than younger kids to have bystander use an AED. Patients who got defibrillator treatment before ambulances arrived were 13 years old on average, compared with an average age of 10 among kids who didn’t get this treatment.

For all kids - but especially younger and smaller children - bystanders may not rush to help during cardiac arrest because they don’t realize it’s possible for kids to have a cardiac arrest, Aziz said by email.

“Sudden cardiac death can occur in any patient, at any age,” Aziz said.

Just 19 percent of the children in the study survived to go home from the hospital.

Still, it’s unclear from the paper how survival differed for kids shocked before ambulances arrived compared with children who got shocked afterwards, said Dr. Myron Weisfeldt, a researcher at Johns Hopkins University in Baltimore who wasn’t involved in the study.

And, in many cases children, like adults, may not be “shockable” or possible to treat with an AED, Weisfeldt said by email.

The results should nonetheless serve as a reminder to parents and caregivers to learn cardiopulmonary resuscitation (CPR) and to recognize the signs of impending cardiac arrest like shortness of breath, nausea, cold sweat, fatigue or sudden dizziness, said Dr. Christopher Fordyce, a researcher at the University of British Columbia and Vancouver General Hospital in Canada who wasn’t involved in the study.

“AEDs are definitely important,” Fordyce said by email. “However, parents and caregivers need to understand that early layperson CPR is also strongly associated with survival, and that everyone has the capability to do this.”

SOURCE: bit.ly/2xFHOUe Pediatrics, online September 27, 2018.