What is therapeutic hypothermia after cardiac arrest?

Therapeutic hypothermia is a type of treatment to lower the body temperature. This reduces injury and long-term problems. It’s sometimes used for people who have a cardiac arrest. Cardiac arrest happens when the heart suddenly stops beating. Once the heart starts beating again, healthcare providers use cooling devices to lower your body temperature for a short time. It’s lowered to around 89°F to 96°F (32°C to 36°C). The treatment often lasts about 24 hours.

The heart has an electrical signal that helps coordinate the heartbeat. If this signal is disrupted or abnormal, the heart may not be able to pump the right way. That can result in cardiac arrest.

Cardiac arrest isn't the same thing as a heart attack. A heart attack happens when part of the heart doesn’t get enough blood. Sometimes cardiac arrest happens during or after a heart attack. But it can also happen without one.

During cardiac arrest, blood doesn’t flow to the organs of the body. The brain may also not get enough blood. That’s why many people don’t recover after cardiac arrest. The lack of blood flow can cause lasting damage to the brain. The person may be unable to regain consciousness. Lowering the body temperature right away after cardiac arrest can reduce damage to the brain. That raises the chances that the person will recover.

Why might I need therapeutic hypothermia after cardiac arrest?

Therapeutic hypothermia can help only some people who have had cardiac arrest. Some people regain consciousness right after cardiac arrest. These people often don't need this procedure. It's helpful only for people whose heartbeat returns after a sudden cardiac arrest but who are still not awake. If the heartbeat doesn’t restart soon, therapeutic hypothermia won't help.

Therapeutic hypothermia can be a good choice if the heart restarted but you're still not responsive. It can raise the chance that you'll wake up.

Experts aren't sure why lowering the body’s temperature reduces brain damage. The chemical reactions and the metabolism of the tissues of the body slow down. The lowered temperature may also decrease inflammation in the brain. Both of these factors may help reduce injury.

What are the risks of therapeutic hypothermia after cardiac arrest?

Therapeutic hypothermia is very helpful for some people. But it has some rare risks. Some of these risks include:

• Another abnormal heart rhythm, especially slow heart rates

• Severe blood infection (sepsis)

• Blood is less able to clot. This can cause bleeding.

• Electrolyte and metabolic problems

• Raised blood sugar levels

• Imbalance of the pH (acid-base) levels in the body

These risks may vary based on your age and other health problems. Ask your healthcare provider about the risks specific to you.

How do I get ready for therapeutic hypothermia after cardiac arrest?

This procedure is used only for people who are unconscious after cardiac arrest. So you can’t prepare for it ahead of time.

It can be helpful for family members to learn about the procedure. While your body temperature is lower, you may look, act, and feel lifeless. You may also have tubes and monitoring devices attached to you. This can be scary. Your family should know that the healthcare providers are working hard to give you the best possible chance of recovery.

What happens during therapeutic hypothermia after cardiac arrest?

Different medical centers may use different methods to do therapeutic hypothermia. In general:

• The medical team may start the hypothermia within 4 to 6 hours after the cardiac arrest.

• A healthcare provider will give you medicine to help you relax (sedative). It makes you sleep and keeps you from shivering. You won't remember anything about the procedure afterward. You may also get another medicine to keep you from moving.

• Your heart rate, blood pressure, and other vital signs will be closely watched. Providers use special thermometers to check your internal temperature.

• The provider may use cooling blankets, ice packs, or cooling pads to bring the body temperature down. The goal is to cool as quickly as possible.

• Another cooling choice is internal cooling. That’s when chilled fluids are given through an IV (intravenous) line into your bloodstream.

• The therapeutic hypothermia will likely last around 24 hours.

• The medical team will slowly rewarm you over a few hours. They may set cooling blankets at gradually warmer temperatures. In some cases, they may also use rewarming devices.

Sometimes providers may do therapeutic hypothermia at the same time as other treatments. For instance, they might do a heart catheterization after a cardiac arrest caused by a heart attack.

What happens after therapeutic hypothermia after cardiac arrest?

The medical team will carefully watch you. You'll be in the intensive care unit (ICU). You may be on a ventilator to help with breathing. You may have various lines and tubes to support body functions.

People don't always respond right away to the procedure. It may take a couple of days. Healthcare providers often wait at least 3 days after the procedure to see how the cardiac arrest affected the brain. The procedure doesn't guarantee that you'll regain brain function. Tests for brain function may be done to see how your brain has recovered. These may include an electroencephalogram (EEG) or a computed tomography (CT) scan of the brain.

Some people do eventually wake up after therapeutic hypothermia. They may not have any lasting brain injury. Others might have some problems with thinking. They'll need physical therapy. Sometimes cardiac arrest may harm other organs, like the kidneys. You'll need follow-up care.

Medical care will depend on the reason for the cardiac arrest and the degree of damage. Other health problems you have will also determine the care you need. You may need medicine, procedures, and physical therapy. Some people might need surgery for heart disease. Other people might need an automatic defibrillator. Almost everyone will need to stay in the hospital for a while. Talk with your provider about what to expect after the procedure.

Next steps

Before agreeing to the test or procedure, make sure you or your family members know:

• The name of the test or procedure

• The reason you're having the test or procedure

• What results to expect and what they mean

• The risks and benefits of the test or procedure

• What the possible side effects or complications are

• When and where you're to have the test or procedure

• Who will do the test or procedure and what that person’s qualifications are

• What would happen if you didn't have the test or procedure

• Any alternative tests or procedures to think about

• When and how you'll get the results

• Who to call after the test or procedure if you have questions or problems

• How much you'll have to pay for the test or procedure