Every year, about 550,000 Americans die of heart attacks, 8,000 drown and 3,000 choke to death on a piece of food. As many as 100,000 of these, doctors say, could be saved by prompt, efficient emergency care starting with those already at the scene.

In an effort to save more of these lives, experts in emergency medicine have simplified the guidelines for lifesaving techniques such as cardiopulmonary resuscitation (CPR) and the Heimlich maneuver.

The changes are part of a continuing push to make bystanders and the community at large the "ultimate coronary care unit" for those who can't make it to the hospital.

Immediate first aid is essential, since between 60 and 70 percent of sudden deaths caused by cardiac arrest occur before the patient gets to a hospital. A person who can't breathe because of a piece of food stuck in the windpipe cannot afford to wait for an ambulance.

The new guidelines, published in the current Journal of the American Medical Association, include technical changes in the teaching and use of CPR and seek to allay fears about contracting infectious diseases such as hepatitis or AIDS while administering mouth-to-mouth resuscitation. They also recommend use of the Heimlich maneuver -- a kind of bear hug from behind -- on all life-threatened choking victims except infants under 1 year.

"I'm gratified," said Dr. Henry Heimlich, professor of advanced clinical sciences at Xavier University in Cincinnati. "It's been 12 years in coming."

Heimlich, a chest surgeon who describes himself as "67 going on 30," first reported in 1974 the success of the abdominal thrust that can expel a piece of food from the throat by upward pressure on the abdomen.

These new emergency-care guidelines were developed last year at a national conference sponsored by the American Heart Association, American Red Cross, American College of Cardiology and the National Heart, Lung and Blood Institute.

It was the fourth national conference on CPR in the past decade and the second revision of the original guidelines, which were published in 1974.

Immediate treatment by bystanders trained in CPR, followed up by paramedics and other trained specialists, can boost a "sudden death" victim's chance of survival from about 5 percent to about 25 percent, studies have shown.

CPR combines mouth-to-mouth breathing, to inflate a victim's lungs, and repeated compression of the chest, to restore blood circulation. More than a million Americans a year are trained in CPR.

But experts worry that in an actual emergency, many bystanders can't remember exactly what to do.

"The theme for the whole conference was to try to make things simpler and less confusing for the layperson," said Dr. William H. Montgomery, an anesthesiologist at the Straub Clinic and Hospital in Honolulu and chairman of the CPR conference.

He said there was unanimous agreement among the panelists at the conference that in an actual emergency, even those trained in CPR and other lifesaving techniques "were not remembering what to do."

Many people at the scene of an emergency have "an overriding fear of doing something wrong," Montgomery said, "and therefore do not proceed at all." But inaction during the "critical window" -- the three or four minutes before the paramedics arrive -- is often tantamount to letting the victim die.

In such cases, Montgomery said, "doing something really is better than doing nothing."

In the new guidelines, the Heimlich maneuver is designated the preferred method to dislodge foreign matter from the airway -- except in infants. Previous guidelines had listed both the abdominal thrust (the Heimlich maneuver) and back blows, without giving preference to either one.

"Back blows have been virtually eliminated," said Dr. Carlotta M. Rinke, an internist who edited JAMA's CPR issue.

The exception is in babies less than 1 year old. In those cases, Rinke said, back slaps are recommended because of a "dearth of scientific data" about the effectiveness of the Heimlich maneuver in infants and fears of damaging internal organs.

Though many experts disagree, Heimlich often refers to back blows as "death blows" because of their potential for driving a blockage "tighter into the lung."

One reason for endorsing use of the Heimlich maneuver in all but infants, Montgomery said, was to eliminate confusion on the part of bystanders about which approach to use -- back blows or abdominal thrust. Such confusion results in hesitation and delays at a crisis.

The new guidelines also allow for use of the Heimlich maneuver for a near-drowning victim whose airway is blocked or when mouth-to-mouth resuscitation does not work.

"I've been after that for about 10 years," Heimlich said, adding that he has received dozens of letters from lifeguards and paramedics who successfully used the maneuver on drowning victims after mouth-to-mouth resuscitation had failed.

"They all said the same thing -- that water gushed from the lungs and the drowning victim recovered," Heimlich said.

But Montgomery said "the wealth of evidence suggests that in most cases only a small amount of water is aspirated into the lungs and that it's not nearly enough to obstruct the airway.

"Doing the Heimlich maneuver in such cases may cause the victim to vomit and aspirate the vomit, making the situation worse instead of better."

Achieving a consensus on the wording of emergency care guidelines was anything but easy, Montgomery said. Controversies such as the back blows-Heimlich debate are compounded by the lack of clear-cut data.

"There were two or more schools of thought for most issues discussed during the conference, each having some reasonable scientific support," Montgomery said in a JAMA editorial accompanying the new guidelines.

The guidelines, 80 pages long and full of technical detail, include the following changes:

Infants. A combination of back blows and chest thrusts is recommended for choking victims under age 1. The infant should be straddled over the rescuer's arm, head down.

CPR. Rescuers will now be taught to administer two initial breaths of about 1.5 seconds each, instead of four quick, full breaths. The recommended number of chest compressions per minute has been increased from 60-to-80 to 80-to-100. Laypeople will be taught only the one-rescuer technque.

Defibrillation. All emergency medical personnel should be trained to recognize ventricular fibrillation -- wildly irregular heart beat -- and to use electrical charges to restore a regular heart beat.

Infectious diseases. Although an estimated 40 million Americans have been trained in mouth-to-mouth resuscitation, there has never been a documented case of disease transmitted during training. Trained emergency medical workers can wear disposable plastic gloves and use plastic face masks with one-way air valves to guard against the "theoretical risk" of contacting contaminated saliva.

More Information

For information about CPR training, call the American Heart Association at 337-6400 or the American Red Cross at 728-6415.