What is brain death?
Brain death is when a person's brain has completely stopped working but the body is being kept alive by breathing machines and medicines.
People who are brain dead are unaware and can't think or feel
They can't move or breathe
Their brain stops controlling automatic body functions such as heartbeat and blood pressure
People don't recover, and the body dies within a few days no matter what doctors do
People with brain death are considered legally dead
Machines can breathe for someone who is brain dead, and medicines can keep the heart beating for a short time. However, eventually, all the person’s organs stop working. If a person wanted to be an organ donor, doctors may be able to use the person's organs for transplant Overview of Transplantation Transplantation is the removal of living, functioning cells, tissues, or organs from the body and then their transfer back into the same body or into a different body. The most common type of... read more . But the organ donation has to be done before the organs stop working.
No one who's brain dead ever recovers. Brain death is different from coma Stupor and Coma Medical problems that affect your brain often keep you from being wide awake and thinking clearly. You may be affected only a little or a whole lot, ranging from being: Slightly less alert than... read more . People in a coma have some brain function and sometimes recover.
What causes brain death?
Brain death is caused by severe brain damage from:
Lack of oxygen to the brain (such as from drowning Drowning Drowning occurs when submersion in liquid causes suffocation or interferes with breathing. During drowning, the body is deprived of oxygen, which can damage organs, particularly the brain. Doctors... read more or cardiac arrest Cardiac Arrest and CPR Cardiac arrest is when the heart stops pumping blood and oxygen to the brain and other organs and tissues. Sometimes a person can be revived after cardiac arrest, particularly if treatment is... read more )
Such problems typically cause brain swelling. The brain swelling raises the pressure inside the person's head. That increased pressure eventually shuts off all blood flow to the brain. Once blood flow has been shut off, brain death occurs.
How can doctors tell if someone is brain dead?
Doctors first make sure the person doesn't have a medical problem that causes a deep coma similar to brain death. Such problems include:
Overdose of certain kinds of drugs
If the person doesn't have one of those problems, doctors do a physical exam to look for signs of brain activity including:
Trying to breathe if the ventilator is turned off
Flinching or moving if the person is pinched or poked by a needle
Gagging on something put in the back of the throat
Blinking if something touches an eyeball
Pupils narrowing in response to a flashlight
If there's no sign of brain activity, doctors sometimes test again 6 to 24 hours later to make sure the person again shows no response. After testing twice with no response, doctors know that the person is brain dead.
Instead of waiting a day to repeat the examination, doctors may do:
Brainwave tests (EEG Electroencephalography (EEG) Brain waves are electrical signals your brain makes. Your brain is always making electrical signals, even when you're asleep. Certain brain problems such as seizures cause changes in your brain... read more ) to see if the brain has any electrical activity
Blood flow tests to see if any blood is getting to the brain
People with no electrical activity or blood flow in the brain have brain death. But these tests aren't required.
What do doctors do if someone is brain dead?
Because brain death means someone is legally dead, the person's organs can be donated to someone in need of an organ transplant Overview of Transplantation Transplantation is the removal of living, functioning cells, tissues, or organs from the body and then their transfer back into the same body or into a different body. The most common type of... read more . Donation doesn't have to wait for the person's heart to stop beating. Organs are taken only if the person or family wishes to donate them. The ventilator and supportive medicines are kept going until this is done. The organs are removed carefully, and the body is treated with great respect. Then doctors:
Turn off the ventilator
Stop any medicines
Release the body to the coroner's office or the funeral home