ľ��ֱ��

Bystanders save lives using defibrillator for cardiac arrest

An automated external defibrillator, or AED, can save the life of someone who has suddenly collapsed and lost consciousness. nazdravie/iStock/Thinkstock

Cardiac arrest is when a person’s heart suddenly stops beating. Unless treated within minutes, the person usually dies because blood is no longer being pumped to the brain and other parts of the body.

Quickly shocking the heart with an automated external defibrillator (AED) can save a person’s life after cardiac arrest. An AED is a portable, battery-operated device that a bystander can use. It checks the heart rhythm and can send an electric shock to the heart to try to restore a normal rhythm. AEDs are in public places like office buildings, schools, and shopping malls. Experts estimate that each year more than 18,000 Americans have a shockable cardiac arrest outside of a hospital that occurs in public with witnesses.

After a 911 call about cardiac arrest is made, an estimated 4 to 10 minutes may pass before emergency medical services arrive. A research team led by Dr. Myron Weisfeldt of Johns Hopkins University explored whether a significant proportion of lives could be saved if bystanders used AEDs before emergency medical services arrived. The study was funded in part by NIH’s National Heart, Lung, and Blood Institute (NHLBI) and National Institute of Neurological Disorders and Stroke (NINDS). Results appeared online on February 26, 2018, in Circulation.

The team analyzed data collected between 2011 and 2015 from a network of six U.S. and three Canadian regions. During this time, emergency medical services treated nearly 50,000 cardiac arrests outside of a hospital. Of those who had an initially shockable heart rhythm observed in public, 469 (19%) were shocked first by a bystander using an AED and 2,031 were shocked first by emergency medical services.

The analysis showed a greater likelihood of survival when a bystander used AED (67%) rather than wait for emergency medical services to shock the heart (43%). In addition, people were more likely to survive with minimal disability after cardiac arrest (57% for AED from a bystander versus 33% for AED initiated by emergency medical services). The more time that elapsed before emergency medical services arrived, the larger the benefit of bystanders using an AED.

“We estimate that about 1,700 lives are saved in the United States per year by bystanders using an AED,” Weisfeldt says. “Unfortunately, not enough Americans know to look for AEDs in public locations, nor are they are trained on how to use them.”

A previous analysis of 2005 to 2009 data by the team found that about 500 additional lives could be saved each year in the U.S. and Canada if bystanders used AEDs. Because of increased availability of AEDs and increased use by bystanders, they now estimate that 3,459 people having a cardiac arrest could be saved each year by bystander AED use.

“Bystanders have the potential to save a life,” Weisfeldt says. “This should be a great incentive for public health officials and bystanders to strive to have AEDs used on all victims of cardiac arrest.”

—by Geri Piazza