Automated external defibrillators at home
As you read this, someone somewhere in the United States is collapsing from a cardiac arrest. The odds are poor that she or he will survive this sudden disruption of the heart's normal rhythm. Most of the 1,000 or so people who go into cardiac arrest each day die because they don't get the treatment they need — an electric shock to the heart — fast enough.
Heart-shocking devices were once found only in hospitals and ambulances. Now they're popping up in airports, movie theaters, fitness centers, casinos, malls, office buildings, and other places. These public versions, called automated external defibrillators (dee-FIB-rih-lay-tors), are so easy to use that sixth graders who have never seen one before can master their use in a minute or so, as shown in a 2002 study. This ease of use, combined with the fact that 3 in 4 cardiac arrests happen at home, have opened a national debate over whether it's a good idea to have a defibrillator at home.The chances of surviving a cardiac arrest fall about 10% for each minute the heart stays in ventricular fibrillation. Shock the heart back into a normal rhythm within two minutes, and the victim has an 80% chance of surviving. Deliver that shock after seven minutes — the average time it takes an emergency medical team to arrive in many cities — and the odds are less than 30%. If someone near you goes into cardiac arrest, calling 911 is a must. Even if there's a defibrillator nearby, you'll need professional help as soon as possible. CPR is also important because it keeps blood flowing to the brain and other vital organs. Still, a home defibrillator could let you restore a healthy heart rhythm several crucial minutes sooner than emergency medical technicians.
Can home defibrillators help?
With a prescription from a doctor and $2,500 or so, you can buy a defibrillator for your home, office, or car at many large pharmacies or medical supply companies. The question is, should you? Experts in the areas of sudden cardiac arrest, emergency medicine, and public health don't see eye-to-eye on this issue. Some argue that people who want to buy defibrillators for their homes should be able to do so without needing a prescription from a doctor. Others argue that people won't maintain the devices so they will be ready when needed, or that most people would be better off spending some of the money on a health club membership and donating the rest to their local emergency response team.
Researchers have collected relatively little evidence on the benefits and risks of wider access to defibrillators. A few studies have examined their use in public places. One, published in the October 17, 2002, Journal of the American Medical Association, showed that 11 of 18 people who collapsed with ventricular fibrillation over a two-year period in Chicago's three airports were revived, mostly by passers-by who used highly visible and well-marked defibrillators.
But their use at home is uncharted territory. One project, Neighborhood Heart Watch, is putting automated defibrillators in volunteers' homes in Indianapolis neighborhoods. When there's a call to 911 about a cardiac arrest in that neighborhood, it's routed to both the emergency services and the nearest home with a defibrillator.
Another study, the Home Automatic External Defibrillator Trial, sponsored in part by the National Institutes of Health, aims to map out the benefits and risks. It will give home defibrillators to 3,500 heart patients and train their partners to use the devices. The partners of another 3,500 heart patients will get training in CPR, but no home defibrillator. The results aren't expected until 2007.
Who should have one?
A home defibrillator would probably be a good investment for anyone who has survived a sudden cardiac arrest but who does not have a pacemaker capable of shocking the heart (an implantable cardioverter/defibrillator, or ICD). Owning this device might also make sense for someone with severe heart failure, unstable angina, or other severe forms of heart disease. So far, though, there's no good evidence that home defibrillators will save lives in this group of people.
Training is a must
If you decide to buy a defibrillator for your home, or if you just want to be prepared for the chance you'll someday need to use one in a public venue, make the time now to take a class on using this device.
Why bother to go through training when these machines have been designed for virtually mistake-free use? Several reasons. A class can help you use the defibrillator with confidence and speed. It can help you deal with unusual situations, such as where to apply the pads on someone with an implanted pacemaker, a medication patch, or a hairy chest. It will also teach you how to do CPR, an important part of the process.
The American Heart Association has developed a 3 1/2-hour course called "HeartSaver AED for Lay Rescuers and First Responders." To find the closest training center that offers this course, call the AHA at 800-242-8721.
January 2003 Update
Children and Peanut Allergies
Children usually outgrow allergies to milk and eggs, but not to peanuts. In a recent study, researchers found that the majority of children with peanut allergies will have adverse reactions to accidental peanut exposure within five years. In addition, allergic reactions are likely to worsen over the years.
Researchers followed 83 children who were diagnosed with a peanut allergy before their 4th birthday. Of these children, 61 had initial non-life-threatening reactions, while 22 had potentially life-threatening reactions. After 5.9 years, they found that 50 of the 83 children had experienced a total of 115 adverse reactions to peanuts.
Most of the reactions increased in severity after the initial reaction. Of the children with initial non-life-threatening reactions who had additional reactions, 44% had at least one potentially life-threatening subsequent reaction. And of the 22 children who had initial life-threatening reactions followed by additional reactions, 71% had at least one additional life-threatening reaction.
In 12 of the original 83 children, the initial reaction occurred after touching, (not eating) peanuts, and they experienced only skin symptoms. Eight of these 12 had subsequent reactions, and all eight had at least one occurrence of respiratory or gastrointestinal symptoms. Children with only skin symptoms had significantly lower serum peanut-specific antibodies than those with other initial symptoms, but there was no "safe" antibody level below which subsequent reactions were only skin-specific.
Most children with peanut allergies accidentally ingest peanuts and this study showed that allergic reactions are likely to get progressively worse with each exposure. Children must be educated to avoid peanuts and foods containing peanuts. In addition, children should always have access to a self-injectable epinephrine kit that both parents and children should know how to use if the need arises.
February 2001 Update