When my father suffered a heart attack and collapsed in a Brooklyn supermarket, he was surrounded by people.

Someone called 911, but although he was unresponsive and not breathing, no one tried to keep his body and brain alive by performing cardiopulmonary resuscitation while waiting for professional help.

He died at the scene.

The failure of anyone to try a lay rescue was not too surprising, given that it was 1982 and relatively few people had been trained in CPR. I had, thanks to a course offered at my office, but I was miles away at the time.

What is surprising is that had my father's sudden cardiac arrest happened under similar circumstances last year, the chances that anyone on the scene would have tried to save him remained remote.

Widespread Efforts

Despite decades of education and widespread course offerings, the survival rate for out-of-hospital cardiac arrest remains a dismal 6 percent or less worldwide.

This fact prompted the American Heart Association last November to simplify the steps of CPR to make it easier for lay people to remember and to encourage even those who have not been formally trained to try it when needed.

"Sadly," the association wrote when it issued the new guidelines, "we have learned that bystander CPR is performed in about only a third of witnessed arrests or fewer, and that when CPR is performed, even by professionals, it is often not done well."

There are many reasons for bystanders' reluctance to try CPR. Some claim the steps have been too complicated and hard to remember. After formal training, the skills decline rapidly. Others fear catching a disease or virus like H.I.V. from the victim through mouth-to-mouth resuscitation, although the risk of transmitting any infection is very low.

Yet the need for bystander CPR is great. Each year, about 250,000 people die outside of hospitals from coronary heart disease, and thousands of others drown or are asphyxiated.

Many of them can be saved if someone nearby is willing and able to immediately perform CPR until professional help arrives.

Furthermore, the life that CPR could help save is most likely that of a family member, friend or neighbor.

Done effectively with minimal delay, CPR can double or triple the survival rate in people who suffer sudden cardiac arrest. But "to be successful, CPR must be started as soon as a victim collapses," the association noted. For every minute without CPR, survival chances fall 7 to 10 percent.

Effective rescues are greatly enhanced if an automated external defibrillator is available to shock the heart back into a normal rhythm. Delivered within three to five minutes of a person's collapse, a shock by a defibrillator can result in survival rates of 49 to 75 percent. This has been proved in settings like airplanes, casinos, stadiums and other locations that keep defibrillators on hand for such emergencies.

Although a brief training session is helpful, the device is self-explanatory and can be used effectively by nearly anyone old enough to handle it. There is nothing to read: the device assesses the victim's heart rhythm and tells you what to do.

The goal of CPR is to push oxygen-containing blood to the brain and body when the heart fails to do this vital job. The new guidelines emphasize the importance of rapid, effective cardiac compressions — pushing hard and fast on a person's chest to squeeze the heart and allow it to refill between pushes.

In the first minute or two after a heart attack that results in cardiac arrest, there is still oxygen in the person's blood, which makes cardiac compressions more important than rescue breathing.

Changes in CPR

Although the new guidelines call for two rescue breaths before starting chest compressions, they "encourage those who would rather not give mouth-to-mouth ventilations to call for help and start chest compressions only."

However, for a drowning victim or child under 8, asphyxia is the more likely cause of cardiac arrest, and getting oxygen into the lungs through rescue breathing, along with aiding circulation, is critical to survival.

Do not, however, do a Heimlich maneuver on a drowning victim before starting CPR since there is not enough water in the lungs to interfere with ventilation. If the victim vomits, turn the head to one side and clear the mouth with your fingers before trying the rescue breathing.

For purposes of CPR, the heart association considers everyone 8 and older to be an adult. Upon witnessing a person's collapse, the lay rescuer who is alone should first call 911 and retrieve an automated external defibrillator if one is readily available. If there is anyone else present, that person should do these first steps, freeing the lay rescuer to assess the situation and start CPR.

Help on the Line

Even if you know nothing about CPR, the 911 operator may be able to talk you through it. With minimal instructions, the mnemonic A-B-C can help you remember the steps.

A: ASSESS First make sure you are in a safe place. Trying CPR on a road risks two lives. To determine responsiveness, tap the victim on the shoulder and ask, "Are you O.K.?" If the victim is unresponsive, tilt his head back and chin up to open the airway and place your cheek next to his mouth to determine if there is effective rhythmic breathing.

Note: Occasional gasps are not normal breathing, and CPR should be started immediately. You no longer have to check for a pulse, which is often hard to find and can waste precious minutes.

B: BREATHE Kneeling perpendicular to the victim, administer two rescue breaths.

With the head tilted and chin up, pinch the victim's nose, place your mouth completely over the victim's and give two breaths, each lasting one second and just forceful enough to see the chest rise and then fall between breaths.

Avoid breaths that are too large or forceful. (If the victim is an infant under a year old, do not pinch the nose; rather, place your mouth fully over the baby's nose and mouth and give two puffs of air.)

C: COMPRESS Then place the heel of one hand on the victim's chest between the nipples (at the base of the sternum).

Place your other hand over the first and press down hard and fast — 100 compressions a minute — so that the chest is depressed by one and a half to two inches in an adult or one-third to one-half of the chest depth in a child under 8.

Only one hand on the chest may be needed for a child; use only two or three fingers for an infant. Be sure to allow the chest to rise between compressions.

Do 30 chest compressions for every two rescue breaths for all victims, stopping compressions for just a few seconds to do the breaths.

Minimize interruptions of chest compressions. To be effective, CPR must restore and maintain adequate blood flow through the heart and to the brain.

With every interruption of chest compressions, the pressure of blood flow through the heart drops and the chances of survival fall.