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Cardiac arrest is what happens when a person dies. The heart does not beat and breathing ceases, which starves the body of oxygen. Sometimes a person can be revived during the first several minutes after cardiac arrest. However, the more time that passes, the less likely it is that the person can be revived and, if revived, the more likely it is that brain damage will have occurred. Brain damage is likely if cardiac arrest lasts for more than 5 minutes, and death is likely if cardiac arrest lasts for more than 10 minutes. Fewer than 5% of people who are not already hospitalized when they have a cardiac arrest survive to be discharged from the hospital, and many survivors have brain damage.
A person in cardiac arrest lies motionless without breathing and does not respond to questions or to stimulation, such as shaking. A rescuer who encounters someone who fits this description first determines whether the person is conscious by loudly asking, "Are you OK?" If there is no response, the rescuer turns the person face up and uses the "look, listen, and feel" approach to determine whether breathing has stopped:
If the person is not breathing, the rescuer checks for airway blockage by looking into the mouth and throat for any visible objects.
First-Aid Treatment
First aid for cardiac arrest should proceed as quickly as possible. An automated external defibrillator (AED—a device that can start the heart beating again) should be used immediately if available. The next step is to call for emergency medical assistance. Next, if the person has not resumed breathing, cardiopulmonary resuscitation (CPR) should be started. CPR combines artificial respiration (mouth-to-mouth resuscitation, rescue breathing), which supplies oxygen to the lungs, with chest compressions, which circulate oxygen to the brain and other vital organs by forcing blood out of the heart.
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Automated External Defibrillator: Jump-Starting the Heart
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An automated external defibrillator (AED) is a device that can detect and correct a specific type of abnormal heart rhythm called ventricular fibrillation. Ventricular fibrillation causes cardiac arrest. If cardiac arrest occurs, an AED, if available, should be used immediately. An AED is used before calling for help and before attempting cardiopulmonary resuscitation (CPR) because an AED is more likely to save lives. If the AED detects ventricular fibrillation, it provides an electrical shock (defibrillation) that can restore normal heart rhythm and start the heart beating again. Emergency medical care should be obtained even if the heart has started beating again. If a person remains in cardiac arrest after an AED is used, CPR should be performed.
AEDs are easy to use. The American Red Cross and other organizations provide training sessions on the use of AEDs. Most training sessions take only a few hours. Different AEDs have somewhat different instructions for use. The instructions that are written on the AED being used should be carefully followed. AEDs are available in many public gathering places, such as stadiums and concert halls. People who are told by their doctor that they are likely to develop ventricular fibrillation but who do not have an implanted defibrillator may want to purchase an AED for home use by family members.
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Skill in CPR is best obtained through a training course. The American Heart Association, American Red Cross, and many local fire departments and hospitals offer CPR training courses. Because procedures may change over time, it is important to stay up to date on training and to repeat courses as recommended.
To begin CPR, the rescuer lays the person face up, rolling the head, body, and limbs at the same time. The rescuer then removes any object visibly blocking the airway. Next, the rescuer tilts the person's head back slightly and lifts the chin, which sometimes opens a blocked airway. If the person does not resume breathing, the rescuer's mouth is placed over the person's mouth and the rescuer begins artificial respiration by slowly exhaling air into the person's lungs (rescue breaths). To prevent air from escaping from the person's nose, the person's nose is pinched shut as the rescuer exhales into the mouth.
Artificial respiration is very similar in children and adults. However, with an infant, the rescuer's mouth is placed over the infant's mouth and nose. To prevent damaging the infant's smaller lungs, the rescuer exhales with less force than with adults.
Failure of the chest to rise after properly delivering rescue breaths indicates that the person's airway is blocked. If the chest rises, the rescuer gives two deep, slow breaths.
Next, chest compressions are performed. The rescuer kneels to one side and, with arms held straight, leans over the person and places both hands, one on top of the other, on the lower part of the breastbone. The rescuer compresses the chest to a depth of 1½ to 2 inches (4 to 5 centimeters) in an adult, less deeply in a child. For an infant, the rescuer uses two fingers to compress the infant's breastbone just below the nipples to a depth of ½ to 1 inch (1 to 2½ centimeters). CPR can be performed by one person (who alternately performs rescue breaths and chest compressions) or by two people (one to perform rescue breaths and one to perform chest compressions). Chest compressions are performed about 100 times per minute. Two breaths are given after each 30 compressions. Performing chest compressions can quickly tire a person, resulting in compressions that are too weak to be effective, so, if two rescuers are present, they should switch duties (the person doing chest compressions should now do rescue breathing and vice-versa) about every 2 minutes. CPR is continued until medical assistance arrives, rescuers are too tired to continue, or the person recovers.
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Opening an Airway in an Adult
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After determining that a person is not breathing, the rescuer looks in the mouth and throat for any visible objects that may be blocking the airway and, if any are present, removes them. If the person does not start breathing, the tongue may be blocking the airway. The rescuer then tilts the person's head back slightly and lifts the chin, moving the tongue and thus opening the airway. If the person still does not start breathing, the rescuer begins artificial respiration. Opening the airway may be done as part of cardiac pulmonary resuscitation (CPR).
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Performing Chest Compressions in an Adult
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To perform chest compressions for cardiac pulmonary resuscitation (CPR), a rescuer kneels to one side and, with the arms held straight, leans over the person and places both hands, one on top of the other just above (about two finger widths) the lowest part of the breastbone (called the xiphoid process). The rescuer compresses the chest about 1½ to 2 inches (4 to 5 centimeters) in adults. The chest is compressed about 100 times per minute.
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Last full review/revision August 2007 by Justin L. Kaplan, MD
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