Every body cell needs oxygen to live. When we breathe, air containing oxygen is taken in and a good oxygen level is maintained in the lungs. From the lungs, oxygen passes into the blood stream. The heart's beating pumps the blood around the circulatory system. This circulates oxygen to the parts of the body - where it passes out of some blood vessels (capillaries) and into the cells. Proper breathing and circulation are needed to provide oxygen. Without oxygen for more than 6 minutes, irreversible cell death starts occurring in the brain and other vital organs. When cells start dying, "biological death" has commenced.

When a person is in full cardiac arrest he will have neither breathing nor circulation and is said to be "clinically dead." Victims in cardiac arrest need cardiopulmonary resuscitation (CPR). CPR combines artificial breathing with chest compressions. This combination provides oxygen to the lungs and circulation to get the oxygen to the brain and other body cells. The aim of CPR is to prevent clinical death from becoming irreversible biological death. Respiratory arrest

Respiratory arrest means that breathing has stopped. The cause can be from an illness or an injury. It is possible for breathing to stop while the heart continues to beat. However, cardiac arrest will occur within a few minutes if breathing is not restored. Respiratory arrest can be caused by:

Drowning, electric shock, suffocation, strangulation, accident, drug overdose, infection, allergic reaction, collapse of a lung, airway obstruction.

Respiratory arrest can be caused by anything that prevents oxygen from getting into the lungs.

The treatment for respiratory arrest is rescue breathing also known as mouth-to-mouth resuscitation.

Rescue breathing procedure

If you find someone who appears unconscious, shake him lightly by the shirt and shout: "Are you OK?" If the person does not respond, shout for help.

Next, make sure the person is lying on his back. To do this without further injuring the person, gently roll his head, body and legs over at the same time. Now, check to see if any air is going in and out of the victim's mouth. Do this by kneeling next to the victim and putting your cheek next to his mouth to feel and listen to any sounds of air flow. Also look at the victim's chest to see if it is moving, which would indicate that some breathing is taking place. This check will take from 3 to 5 seconds.

Now, open the airway by pushing up on the chinbone. Do not put your thumb into the victim's mouth. Put your other hand on top of his head to help tilt the head back.

Now that you have the airway open and the chin tilted back, use the fingers of your other hand, with your palms on the victim's forehead, to pinch his nose closed. Now do the following:

1. Open your mouth wide.

2. Put your mouth over the victim's mouth, making a tight seal.

3. Breathe out a breath strong enough to fill the victim's lungs.

4. Lift your mouth and look at his chest.

5. Listen for breath sounds and look at his chest for movement.

6. Blow a second breath into the victim.

Then, for 10 seconds, check the pulse on the side of the neck. If there is a pulse, continue mouth-to-mouth rescue breathing for the victim by giving a breath every 5 seconds. Every minute, stop and check the pulse for 10 seconds to make sure there is still a pulse.

Continue until the victim starts breathing on his own, until help arrives, or until you are completely exhausted. If there is no pulse and if you are trained, give CPR.

If you are not trained in CPR, now is the time to get prepared for the No. 1 medical emergency in the United States - heart attack. Call the Utah Heart Association at 1-800-523-7472 or the Utah Emergency Medical Training Council in Midvale at 562-2663 for times, dates and locations of CPR training.

Call the National Safety Council First Aid Institute at 1-800-621-7619, Ext. 7206, if you would like to qualify as a training agency to offer first aid courses.

- Alton Thygerson is a professor of health sciences at Brigham Young University.