Each day in the United States, 1000 people die of sudden cardiac arrest that occurs outside of a hospital or other health care facility. In many cases of cardiac arrest, the heart muscle quivers uncontrollably (called fibrillation) rather than beating in a controlled rhythm. Doctors and emergency medical personnel use a device called a defibrillator to give the heart an electric shock, hoping to restart the proper rhythm. Many public places, such as airports and casinos, now have portable automated defibrillators that a minimally trained person could use. But can minimally trained, and even completely untrained, people use these devices to save a person from cardiac arrest?
New research in the October 17, 2002
New England Journal of Medicine
suggests that even untrained bystanders and airport employees can use the automated defibrillators to save the lives of people in cardiac arrest.
Researchers from the University of Chicago and the University of Texas Southwestern Medical Center collaborated with Chicagos Department of Aviation and Fire Department on this study. They studied the use of automated external defibrillators (AEDs) at three Chicago airports (OHare, Midway, and Meigs) between June 1, 1999 and May 31, 2001.
Specifically the researchers looked at:
- If the patient was revived
- If the patient was alive after 72 hours and also after one year
- How many minutes passed between the time a rescuer called for help or accessed the AED and the time the first shock was delivered to the heart
- If the patient was given CPR
- The neurologic state of the patient at the scene and also one year later
- Who the rescuer was and whether he or she was trained in using an AED or had any other medical training
Researchers collected this information by reviewing paramedics records, security officers reports, information from the AEDs data storage cards, and hospital records. They also interviewed rescuers, witnesses, and patients who survived.
During the two-year study period, a total of 18 people had cardiac arrest with ventricular fibrillation in the three Chicago airports. Of these 18 people, 11 were revived in good neurologic condition, and 10 of the 11 were still alive without neurologic deficit after one year. This translates to a long-term survival rate of 56%”a vast improvement over the 5% for conventional rapid response emergency medical services. Although 7 of the rescuers had no training in using an AED, 3 of these 7 were physicians.
Another important finding was that patients who were defibrillated with an AED within 5 minutes of going into cardiac arrest had a 67% survival rate. Research has shown that survival rates drop drastically when defibrillation is delayed beyond 5 minutes, and plummet further after 10 minutes. Often, emergency medical response teams are not able to get to a patient within 5 to 10 minutes.
Its reassuring to note that in the few cases where a rescuer tried to use the AED on a person without fibrillation, the AED detected a normal heart rhythm and did not deliver a shock.
Although these findings suggest that anyone can successfully use an AED to revive a person in cardiac arrest, this study has its limitations. The study was conducted in airports serving a major metropolitan area where medical professionals are frequent travelers. Medical professionals may be more comfortable using an AED even if they dont have any specific training in using the device. More research is needed in areas where potential rescuers are less likely to have medical training. In addition, all survivors were given CPR at some point during the rescue effort, so the role of AEDs separate from CPR is still not clear. Finally, this was a descriptive study, which means that researchers simply studied the events and reported the outcomes. This type of research provides helpful information about the possible efficacy of AEDs in public places, but a study comparing survival rates in places with and without AEDs would provide more compelling evidence.
These findings suggest that people not trained in the use of AEDs are capable of following the directions printed on the AED to successfully revive a person in cardiac arrest. Use of an AED does not guarantee the survival of a person in cardiac arrest, however. An AED simply restarts a more coherent heart rhythm when the heart is in fibrillation. It does not help with other problems occurring during cardiac arrest.
Should we have AEDs in all public places? That question is hotly debated. Studies like this one are needed to determine if AEDs in public places translate to lives saved”and at what cost. An AED costs $2500, and they are not covered by health insurance. Only about 25% of cardiac arrests that occur outside of medical facilities occur in public places. The rest happen in the home. Perhaps a better question is: Should people be able to buy AEDs for their homes without a prescription? But thats a question for another study to address.
Last reviewed Oct 17, 2002 by
Richard Glickman-Simon, MD
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