People without formal medical training can be taught to effectively use portable, computerised devices, which detect ventricular fibrillation and deliver electricity to restore a normal heart rhythm in people who have a cardiac arrest, according to two studies in the New England Journal of Medicine (2000;343:1206,1210).

Dr T D Valenzuela and colleagues at the University of Arizona found that 53% of 105 people treated with an automated external defibrillator (AED) by security guards in casinos survived and were discharged from hospital. The survival rate rose to 74% for people who were treated within three minutes after collapse.

Another study by Dr R L Page and colleagues at the Southwestern Medical Center at the University of Texas found a 40% survival rate for 15 people who were treated by flight attendants. They also found that AEDs could be effectively used to monitor heart rhythms in people who were not in ventricular defibrillation.

An estimated 225 000 episodes of sudden cardiac arrest occur outside a hospital in the United States. Only 2-5% of people are successfully revived, according to the president of the American Heart Association (AHA), Rose Marie Robertson.

The AHA has called for widespread distribution of AEDs in ambulances, fire trucks, police cars, public buildings, sports arenas, theatres, airports, and airliners. "Taken together, these studies provide strong evidence that trained personnel can intervene effectively when witnessed cardiac arrest is due to ventricular fibrillation," Dr Robertson said.