Protecting the Brain Immediately After Cardiac Arrest

Can we save the brain from more injury?

There are several treatments and procedures that healthcare providers may utilize after cardiac arrest to protect the brain and heart from further damage.

Cooling treatment

Therapeutic hypothermia, also known as a cooling treatment or targeted temperature management, are different name for a type of treatment used in cardiac arrest patients that survive initial resuscitation efforts (chest compressions, electrical shocks) but remain comatose (unresponsive and unable to follow basic commands). It involves purposefully lowering the body temperature to maintain a cooler or normal temperature for 24h or longer to protect the brain from further damage. This is usually done in an intensive care unit (ICU) but sometimes may be started in the Emergency Department (ED).

During cardiac arrest, the blood stops flowing to many organs in the body, including the brain. When these organs stop receiving oxygen and nutrients, it leads to the death of cells. The brain in particular is very sensitive to damage. The idea behind the cooling treatment is that when the body temperature is lowered, some of the brain activities will also require less energy and go into “rest” mode. Decreasing the temperature can also reduce brain inflammation, like when we bump our knee and put ice to prevent or help with the swelling!

What does temperature control entail?

In order to lower the body temperature, doctors will either place catheters (called “lines” by healthcare providers) into the large veins in your body where cold fluids will circulate or place pads on your body that will be cooled through a temperature control unit. This machine will control how fast the temperature drops, how long the target temperature is maintained, and how quickly the body is rewarmed. During this time, doctors may use medications to keep your loved one comfortable and to prevent shivering, as it reduces the benefit of cooling on the brain. After the planned time of cooling treatment ends, the medical team will slowly take off sedating medications to allow awakening. This treatment, however, does not guarantee that your loved one will wake up or go back to how they were before the cardiac arrest. It provides them with the best possible chance to heal and prevent more damage.

Infections

Sometimes your loved one may develop a lung infection (pneumonia) if they require mechanical ventilation for a long time or if their saliva went into the wrong pipe while unconscious. They will receive antibiotics to treat the infection, and samples of lung secretions may be sent to find the cause of the infection. It is important to promptly address an infection as soon as it is suspected, as this can prolong the ICU stay and cause further complications (i.e. spread of infection to the bloodstream, affecting blood pressure and heart rate, and potential prolonged need for mechanical ventilation).

Seizures

There may be times when the medical team will suspect seizures or convulsions that are disturbances in brain electrical activity due to brain damage. Sometimes it may also be challenging to know if your loved one is having seizures if sedative and paralytic medications are being used, as they keep the body still, relaxed, and sleepy, masking any seizure movements that may be happening. 

To truly confirm if the brain is having seizures, your loved one may be connected to an electroencephalogram (also called EEG). This involves pasting metal discs (electrodes) with thin wires onto the scalp (think of it as an EKG, or electrocardiogram, but for the brain).  The brain activity is then recorded in real-time and shows up on a computer as wavy lines. It will alert doctors if your loved one is having seizures, even if the body does not display any abnormal movements. If they are indeed having seizures, doctors will start antiseizure medications that can eventually be stopped once they are controlled. It is extremely important to treat and prevent more seizures as leaving them untreated can potentially cause further brain damage.

Sources

Therapeutic Hypothermia After Cardiac Arrest: https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/therapeutic-hypothermia-after-cardiac-arrest

Electroencephalogram (EEG): https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/electroencephalogram-eeg

Thank you to our contributors

Samantha Fernandez & Sachin Agarwal