Cardiac arrest is what happens when a person dies. The heart stops pumping blood and oxygen to the organs, brain, and tissues. 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 the person will have suffered brain damage.
Brain damage is likely if cardiac arrest lasts for more than 5 minutes, and death is likely if cardiac arrest lasts for more than 8 minutes. Thus, first aid for cardiac arrest should proceed as quickly as possible.
Cardiac arrest can be caused by anything that causes death. One common cause, especially in adults, is an abnormal heart rhythm (arrhythmia). Another possible cause is stopping breathing, such as when a person drowns or has severe pneumonia.
A person in cardiac arrest lies motionless without breathing and does not respond to questions or to stimulation, such as shaking.
Recognition and treatment of cardiac arrest should ideally occur at virtually the same time. A rescuer who finds someone unconscious should first determine if the person is unresponsive by shaking the person and loudly asking, "Are you OK?" If there is no response, the rescuer should turn the person's body face up and look to determine whether breathing has also stopped.
If the person does not respond to stimulation and is not breathing or is breathing abnormally (for example, gasping), emergency resuscitation measures are begun and emergency medical assistance should be sought, for example, by calling 911 or the local emergency service.
The emergency service dispatcher may help direct the resuscitation.
An automated external defibrillator (AED) should be used first or as soon as it becomes available. An AED can rapidly determine whether the person has an abnormal heart rhythm that can be treated by an electric shock (called defibrillation). If the AED detects an abnormal rhythm causing cardiac arrest that could be corrected, it delivers a shock, which often starts the heart beating again. AEDs are easy to use and are available in many public gathering places. Instructions for correct use, available on each AED, should be carefully followed. The American Red Cross and other organizations provide training on the use of AEDs.
Automated External Defibrillator: Jump-Starting the Heart
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 done.
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.
If a person remains in cardiac arrest after an AED is used, other measures are begun, such as opening the airway, starting cardiopulmonary resuscitation (CPR), and giving naloxone or epinephrine.
Skill in CPR is best obtained through a training course, such as one offered by the American Red Cross or the American Heart Association. Training courses can be found through the web site of the American Red Cross or the American Heart Association. Taking periodic refresher courses can help because procedures may change over time.
There are two CPR methods:
- Standard (done by rescuers trained in standard CPR)
- Compression only (done by rescuers untrained in—or reluctant to do—artificial respiration)
Standard CPR combines artificial respiration (mouth-to-mouth resuscitation, or rescue breathing) to supply oxygen to the lungs with chest compressions, which circulate oxygen to the brain and other vital organs by forcing blood out of the heart.
In adults, children, and infants, CPR begins with chest compressions.
In newborns and in people suspected of having a respiratory arrest (such as drowning victims), CPR begins with artificial respiration.
To do chest compressions in an adult, the rescuer lays the person face up, rolling the head, body, and limbs at the same time. The rescuer extends his or her arms and "locks" them straight at the elbows, leans over the person, and places both hands, one on top of the other, on the lower part of the breastbone. The rescuer then compresses the chest to a depth of about 2 to 2.4 inches (5 to 6 centimeters). In children, the rescuer uses only one hand to compress the chest about 2 inches (5 centimeters). For an infant, the rescuer uses two fingers to compress the infant's breastbone just below the nipples to a depth of 1½ inches (about 4 centimeters).
Opening an Airway in an Adult
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 cardiopulmonary resuscitation (CPR).
To do artificial respiration, the rescuer first looks in the mouth and throat for any visible objects that may be blocking the airway and, if any are present, removes them. The rescuer then opens the airway by tilting the head and lifting the chin (see Figure: Opening an Airway in an Adult.). The rescuer's mouth covers the person's mouth and then the rescuer exhales air into the person's lungs (rescue breaths). The person's airway must remain opened during artificial respiration. To prevent air from escaping from the person's nose, the person's nose can be pinched shut as the rescuer exhales into the mouth. Artificial respiration is very similar in children and adults.
When a rescuer does artificial respiration on an infant, the rescuer's mouth covers the infant's mouth and nose. To prevent damaging the infant's smaller lungs, the rescuer exhales with less force than with adults. If the chest rises, the rescuer should give two deep, slow breaths. Failure of the chest to rise after properly delivering rescue breaths indicates that the person's airway is blocked, but CPR should continue. Each time the airway is opened during CPR, the rescuer should look for an object in the victim’s mouth and, if one is found, remove it.
Standard CPR can be done by one person (a single person alternately does rescue breaths and chest compressions) or by two people (one to do rescue breaths and one to do chest compressions). In standard CPR, the rescuer gives 30 compressions and then two breaths. When children or infants need CPR, if two rescuers are present, a ratio of 15:2 is preferred, whereas in newborns, a rate of 3:1 is recommended. Compressions are done at a rate of 100 to 120 times per minute in people of all ages. CPR is continued until medical assistance arrives or the person recovers.
Compression-only CPR (hands-only CPR) involves chest compressions only without artificial respiration. Compression-only CPR is currently recommended when the rescuer does not have CPR training or is trained only in chest compressions. For infants, children, and people in whom the cause of cardiac arrest seems to be stopping breathing, such as those who have drowned, rescuers should do artificial respiration; however, if they are unwilling or unable to do artificial respiration, they should still do compression-only CPR.
Chest compressions can quickly tire a person, resulting in compressions that are too weak to be effective. Thus, if two rescuers are present, they should switch duties every 2 minutes.
Emergency medical care is required for all people who respond to CPR.
Performing Chest Compressions in an Adult
To do 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 2 to 2.4 inches (5 to 6 centimeters) in adults. The chest is compressed about 100 to 120 times per minute.
Performing Chest Compressions in an Infant or a Child
More Information about Cardiac Arrest
- American Heart Association: Cardiac arrest
- American Red Cross
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