What It Means to Be Declared Brain Dead

Signs of Brain Death and Tests to Confirm It

Medically reviewed by Isaac O. Opole, MD, PhD

Brain death is a clinical and legal definition of death. A person who is brain dead may still show signs of life such as warm skin, a heartbeat, and a chest that rises and falls with ventilation. Even though a brain-dead person may appear to be alive, the brain is significantly damaged and recovery is impossible.

Lack of response to stimuli is one of the criteria healthcare providers use when declaring someone brain dead. Some of the other criteria include an absence of reflexes and an inability to breathe without a ventilator.

This article discusses brain death, what it is, and how healthcare providers know when a person is brain dead.

What Causes Brain Death?

Brain cells do not effectively regenerate. This makes it difficult for the brain to recover from injury. When brain cells undergo permanent damage, they cannot be replaced. Major loss of brain function results in brain death.

A few major medical conditions can lead to brain death, such as:

• Stroke

• Heart attack

• Head trauma

• Oxygen starvation

• A brain tumor

• A brain infection such as encephalitis
  

Declaring a Person Brain Dead

Brain death means that a qualified physician, typically a neurologist, did an extensive physical examination and documented brain death criteria.

When a person is pronounced brain dead, this means that they are legally dead. Their death certificate will reflect the date when brain death was pronounced, not when their heart stops at a later time.

In the United States, if a person is pronounced brain dead and meets certain medical criteria, organ donation may be an option. In many cases, the individual has already made their decision to donate and has indicated their choice on their driver's license or in their will.

Signs of Brain Death

Before brain death is pronounced, three clinical criteria must be met:

• Unresponsiveness: To determine responsiveness, the healthcare provider will look for evidence that the person is aware of visual, auditory, and tactile stimulation.

• Absence of reflexes: The healthcare provider will check to see if the person has lost reflexes such as the gag and cough reflex. They will also check to see if the pupils remain fixed in response to light.

• Apnea: Apnea is the inability to breathe without a ventilator. To check for this, the person will be disconnected from the respirator to see if they can take a spontaneous breath without it.
  

Brain Dead vs. Comatose

Brain death is not the same thing as being comatose. A person who is comatose is unconscious and may look the same on the outside as a person who is brain dead, but they continue to have brain activity. It is possible for a comatose person to regain consciousness, but a brain-dead person does not have any brain activity and has no chance of recovery.

Testing for Brain Death

Some medical conditions can look like brain death. This is why the first thing healthcare providers usually do is determine whether the person has a reversible condition that can mimic brain death. For example, a person with extreme hypothermia may not respond to the stimulus used to determine whether or not someone is brain dead.

Paralyzing drugs can also affect the tests. If the person has been given sedation, for example, the brain death tests can't be performed until the medication has had time to leave the body. Other medical conditions such as very low blood pressure or severe electrolyte imbalances also need to be corrected before the assessment can be done.

Physical Examination

The physical examination is done to determine the level of responsiveness. If the examination shows a lack of responsiveness, the physical exam would proceed to check for certain reflexes.

Someone who is brain-dead will not have any brainstem reflexes. For example, a person in a coma who is not brain dead would blink or move their head if their eye is irritated with a piece of a cotton ball. A person who is brain dead cannot blink, flinch, or try to move away if the healthcare provider touches their eye with a fuzzy piece of cotton. Therefore, if there is no blink reflex, that implies that the brainstem is not functioning properly.

Another type of physical testing is the cold caloric. This test is done by using a syringe of ice-cold water and injecting it into the ear canal. A patient who is brain dead will have no response to this type of stimuli, but an individual who has brain function will have a response, which can range from eye movement to vomiting.

Apnea Testing

A patient who is sick enough for brain death testing will be on a ventilator and will not be able to breathe without one. To test if the breathing reflex is intact or absent, the ventilator is removed in a procedure called an apnea test.

Typically, an arterial blood gas (ABG) is drawn immediately before removing the ventilator. Oxygen may be given during the apnea test, but the ventilator cannot be used.

Most people, even those who have severe illnesses, will attempt to draw a breath when a ventilator is removed, but someone who is brain-dead will not take a breath during apnea testing.

Takeaway

When a person is brain dead, the brain is unable to send the signal to breathe and breathing does not happen without the support of a ventilator.

Other Brain Death Testing

After completing the physical assessment, the physician may elect to order additional testing. While it is typical for both a physical assessment and an apnea test to be done, some people who are not brain dead cannot tolerate apnea testing. Often, in those cases, a flow study will be done.

Flow studies check to see if blood is traveling to the brain through the bloodstream. If the study shows that no blood is reaching the brain, the test is consistent with brain death.

Some physicians will use an EEG, or electroencephalogram, which is a test that measures brain waves. A person who is brain-dead will have a "flat" EEG, as brain waves will be absent.

Atropine, a prescription medication that causes the heart rate to increase, can also be administered as an ancillary test for brain death because it is not effective in brain-dead individuals. If the heart rate increases notably after the medication is given, this suggests that a person is not brain dead.

Related: Confirmatory Tests for Brain Death

Understanding Organ Donation

If a person has agreed to donate their organs after death, their body will need to be maintained on life support until their organs can be harvested. This prevents tissue death, which can damage the organs and make them unsuitable for transplant.

It is important to keep in mind that even though the person is still warm and breathing, they are clinically dead and will not feel any pain during the procedure. Once the ventilator is turned off, the heart will stop beating and breathing will cease.

Summary

Brain death means a person's brain has been significantly damaged and has lost important function. A person who is brain-dead feels no pain and will not recover.

Healthcare providers use a series of tests to determine whether or not someone is brain dead. This includes testing the person for responsiveness to certain stimuli and checking to see if their reflexes are functioning. The person will also be checked to see if they can breathe without a ventilator. In some situations, a healthcare provider may also decide to do other tests such as a flow test or EEG.

Read the original article on Verywell Health.