Fact sheet Patient conditions

Published on 1 Jul 2015

Cardiac arrest

What is a cardiac arrest?

A cardiac arrest is when the heart suddenly stops pumping. There are a range of reasons why this may happen, but it is usually the result of a heart attack (‘myocardial infarction’).

Other conditions that can cause a cardiac arrest include bleeding in the brain, severe chest injury, large loss of blood, imbalances of vital body chemicals or heart rhythm irregularities.

What does the cardiovascular system do?

The cardiovascular system is made up of the heart, lungs and blood vessels, all working together. It moves vital nutrients, gases and hormones around the body.

More about the cardiovascular system

What happens when someone has a cardiac arrest?

When someone suffers a cardiac arrest, they become unconscious, stop breathing and have no pulse. When this happens, the heart must be started again as soon as possible, so the brain and other vital organs can get the oxygen they need. After three minutes without oxygen, the brain cells start to die.

The sooner the heart can be started again, the better the chance of recovery of the person having the cardiac arrest. How well the person is able to recover also depends on how well their heart is able to pump once restarted and their general health.

How is cardiac arrest treated?

When someone suffers a cardiac arrest, their heart must be made to start beating again as soon as possible. This means calling an ambulance and doing cardiopulmonary resuscitation (CPR) until it arrives.

Once the ambulance arrives, the paramedics may continue CPR and connect the person to a machine called a defibrillator. This sends an electrical current to the heart to try to start it pumping again. The person will then be transported to hospital and admitted to a coronary care or intensive care unit (ICU), where they will receive further treatment.

What happens in intensive care?

Treatment given in the ICU may be straightforward or complex, depending on the individual situation. Some people stay unconscious after having a cardiac arrest, and need intubation and ventilation with a breathing machine. The medical staff will try to find out the cause of the cardiac arrest and provide any necessary treatment.

A number of chest x-rays and blood tests may need to be done, and the patient will be closely monitored using an arterial line, oxygen saturation monitor and bedside monitor. They may also receive intravenous fluids and have an indwelling urinary catheter and nasogastric tube. If they remain unconscious, more investigations and treatments may be needed.

Generally, the longer the time the heart stopped for, and the longer the person remains unconscious, the worse their outlook is. If their heart stopped for longer than four minutes, they may suffer a brain injury because their brain was starved of oxygen for too long. If their heart stopped for more than 10 minutes, they may not recover at all. Other signs they may not recover are if they stay unconscious for longer than 24 hours, or have fitting (seizures), or abnormal heart rhythms (arrhythmias).

The ICU staff will do all they can to bring about recovery.

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