Most people who have life-threatening brain injuries (regardless
of cause) lose consciousness. Emergency medical treatment is
focused on airway, breathing, and circulation (known as the "ABC's") because these basic functions must be addressed first for your survival.

Airway: When you are unconscious, you may not realize that you cannot breathe. There may be food or other solid material in
your mouth that interferes with your ability to breathe, or your tongue may block your airway. These obstructions must be removed in order for you to get air. If they are not, you may suffer irreversible brain injury and die, even though your brain
was trying to get you to breathe.

Breathing: A brain injury may result in severe enough brain
damage to affect your ability to breathe on your own. The brain
automatically senses when and how often we need to breathe,
and serious brain injury may interfere with the brain's
interpretation of "need-to-breathe" signals from the rest of the
body. Because of this, most head-injured people need to have a tube inserted into through the mouth or nose into the lungs so that a ventilator can be used. The ventilator pumps oxygen into your lungs and allows carbon dioxide to escape. Without this
important help, many patients would die from their brain injury almost immediately.

Circulation: Severe brain injury may cause a reflex reaction in the
body that initially causes the blood pressure. to be very high and
the heart rate to be very slow. This is often followed by a
collapse of the blood pressure. Drugs may need to be given to
help the heart generate a more normal blood pressure. Without
this artificial boost, the low blood pressure may lead to further
damage if not enough blood and oxygen reach the brain.