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Brain Hypoxia


Brain hypoxia is when the brain isn’t getting enough oxygen. This can occur when someone is 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?

There are many medical conditions and events that interrupt the flow of oxygen to your brain. Stroke, cardiac arrest, and an irregular heartbeat can prevent oxygen and nutrients from traveling to the brain.

Other possible causes of oxygen depletion include:

  • hypotension, which is 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 extreme asthma attacks

Who Is at Risk for Brain Hypoxia?

Anyone who experiences an event where they aren’t getting enough oxygen is at risk for brain hypoxia. If your job or regular activities involve situations that deprive you of oxygen, your risk is greater.

Sports and Hobbies

Participating in sports where head injuries are common, such as boxing and football, also 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’re at risk if you have a medical condition that limits the transfer of oxygen to your brain. These conditions include:

  • amyotrophic lateral sclerosis (ALS), which is 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:

  • seizure
  • 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. The tests may include:

  • a blood test that shows the amount of oxygen in your blood
  • an MRI scan, which shows detailed images of your head
  • a CT scan, which provides a 3-D image of your head
  • an echocardiogram, which provides an image of your heart
  • an electrocardiogram, which measure your heart’s electrical activity
  • an electroencephalogram (EEG), which measures the electrical activity of your brain and pinpoints seizures
  • a brainstem auditory evoked response (BAER) test, which shows 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 ventilator (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 receive medication for blood pressure issues or to control your heart rate. Seizure-curbing medicines or anesthetics may also be part of your treatment.

Recovery and 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 may have recovery challenges that eventually resolve. The potential challenges include:

  • insomnia
  • hallucinations
  • amnesia
  • muscle spasms

Patients whose brain oxygen levels have been low for longer than 8 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. 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 unexpectedly deprived of oxygen, such as during a fire, immediate cardiopulmonary resuscitation (CPR) helps to prevent the condition from getting worse.

Content licensed from:

Written by: Chitra Badii and Marijane Leonard
Medically reviewed on: Oct 06, 2015: Deborah Weatherspoon, PhD, MSN, RN, CRNA

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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