Brain Hypoxia

Written by Chitra Badii and Marijane Leonard | Published on July 25, 2012
Medically Reviewed by George Krucik, MD


Brain hypoxia, also called cerebral hypoxia, is decreased oxygen in the brain. You are at risk for this condition if you are drowning, choking, suffocating, or in cardiac arrest. Brain injury and carbon monoxide poisoning are other possible causes of brain hypoxia. The condition can be serious because brain cells need an uninterrupted flow of oxygen to function properly.

What Causes Brain Hypoxia?

A variety of medical conditions and events that interrupt or stop the flow of oxygen to your brain can cause hypoxia. Stroke, cardiac arrest, and irregular heartbeats can prevent both oxygen and nutrients from traveling to the brain.

Other possible causes of oxygen depletion include:

  • hypotension (extremely low blood pressure)
  • anesthesia complications during surgery
  • choking
  • carbon monoxide poisoning
  • drowning
  • breathing in carbon monoxide or smoke
  • traveling to high altitudes (above 8,000 feet)
  • brain injury
  • strangulation
  • medical conditions that make it difficult to breathe, such as an extreme asthma attack

Who Is at Risk for Brain Hypoxia?

You are at risk for brain hypoxia if you are in situations that might cause it. If your job or regular activities are linked to the causes, your risk is greater.

Sports and Hobbies

Participating in sports where head injuries are common, such as boxing and football, puts you at risk for brain hypoxia. Swimmers and divers who hold their breaths for long periods of time are also susceptible. Mountain climbers are at risk as well.

Medical Conditions

You are at risk if you suffer from a medical condition that limits the transfer of oxygen to your brain. These conditions include:

  • amyotrophic lateral sclerosis (ALS), a degenerative disease affecting the nerves in the brain and spinal cord
  • hypotension
  • asthma

What are the Symptoms of Brain Hypoxia?

Brain hypoxia symptoms range from mild to severe. Mild symptoms include:

  • temporary memory loss
  • reduced ability to move your body
  • difficulty paying attention
  • difficulty making sound decisions

Severe symptoms include:

  • seizures
  • coma
  • not breathing
  • brain death

How Is Brain Hypoxia Diagnosed?

Your doctor can diagnose brain hypoxia by examining your symptoms, recent activities, and medical history. A physical exam and tests are usually part of the process. Tests may include:

  • blood tests that show the amount of oxygen in your blood
  • magnetic resonance imaging (MRI) scan to show detailed images of your head
  • computed tomography (CT) scan for a three-dimensional image of your head
  • tests that take a picture of your heart (echocardiogram) and measure its electrical activity (electrocardiogram)
  • electroencephalogram (EEG) to examine the electrical activity of your brain and pinpoint seizures
  • brainstem auditory evoked response (BAER) to see how your brain reacts to sounds

How Is Brain Hypoxia Treated?

Brain hypoxia requires immediate treatment to restore the flow of oxygen to your brain.

The exact course of treatment depends on the cause and severity of your condition. For a mild case caused by mountain climbing, for example, you would immediately return to a lower altitude. In more severe cases, you need emergency care that places you on a respirator (breathing machine).

Your heart may need support as well. You might receive blood products and possibly fluids through an intravenous tube.

Seeking immediate treatment reduces your chances of brain damage.


You may also be given medication for blood pressure issues and/or to control your heart rate. Seizure-curbing medicines or anesthetics may also be part of your treatment.

Recovery Long-Term Outlook

Recovering from brain hypoxia depends largely on how long your brain has gone without oxygen. Depending on the severity of your condition, your recovery challenges might include insomnia, hallucinations, amnesia, and muscle spasms that may eventually resolve. Patients whose brain oxygen levels have been low for longer than eight hours usually have a poorer prognosis. For this reason, people with severe head injuries are usually monitored in the hospital immediately after injury to make sure their brains are getting enough oxygen.

Can You Prevent Brain Hypoxia?

You can prevent brain hypoxia by monitoring certain health conditions. For example, see a doctor if your blood pressure is too low, and keep your inhaler nearby at all times if you are asthmatic. Avoid high altitudes if you are susceptible to altitude sickness. For people who are unexpectedly deprived of oxygen (during a fire, for example), immediate cardiopulmonary resuscitation (CPR) helps to prevent the condition from getting worse.

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