What is anoxia?

Anoxia happens when your body or brain completely loses its oxygen supply. Anoxia is usually a result of hypoxia. This means that a part of your body doesn’t have enough oxygen. When your body is harmed by a lack of oxygen, it’s called a hypoxic-anoxic injury.

Hypoxia can be a consequence of many conditions. These include:

  • low oxygen at high altitudes
  • significant blood loss
  • carbon monoxide and other poisonings
  • breathing difficulties that lower oxygen supply, like asthma or pneumonia
  • low blood flow to organs, such as from a stroke or heart problem
  • sudden injuries that affect breathing, such as near-drowning or choking

When hypoxia turns into anoxia, the parts of your body that need oxygen to function can stop working properly. This includes your:

  • brain
  • heart
  • kidneys
  • bodily tissues

A complete lack of oxygen can be harmful or even deadly if it goes untreated. If you think you’re experiencing signs or symptoms of hypoxia, seek immediate medical attention. Don’t wait until symptoms start to point to anoxia.

Anoxia can be especially harmful to your brain. After about four to five minutes without oxygen, your brain can become permanently damaged. Without oxygen, your brain cells can die, and many of the functions that your brain controls can be affected. The longer your brain goes without enough oxygen, the more likely you may experience long-term complications, including death.

The symptoms of anoxia may not always be obvious at first. Your brain can last a few minutes without oxygen before any symptoms appear. At times, symptoms may be delayed and take several days or weeks to appear.

The first noticeable symptoms of anoxia can include:

  • mood and personality changes
  • memory loss
  • slurred speech or forgotten words
  • changes in judgment
  • trouble walking or moving your arms or legs normally
  • weakness
  • feeling dizzy or disoriented
  • unusual headaches
  • trouble concentrating

Other symptoms may become noticeable after your brain has been without oxygen for more than four to five minutes.

These include:

If you or someone around you is experiencing any of the above symptoms, seek immediate emergency medical attention.

Each type of anoxia has a different internal or external cause. For example, internal causes include your heart or blood vessels not getting oxygen to your brain. External causes include less available oxygen or inhaling environmental toxins.

Anemic anoxia

Anemic anoxia occurs when your blood can’t carry enough oxygen around your body to keep your organs functioning properly.

Hemoglobin, a type of protein in your blood that contains iron, is used to deliver oxygen to your organs and tissues. When your blood doesn’t have enough hemoglobin or the hemoglobin is ineffective, your total oxygen supply decreases. This lack of oxygen can cause anemic anoxia.

The levels of hemoglobin in your body can be lowered for a number of reasons, including:

  • low hemoglobin that is reversible, like from low iron (iron deficiency anemia)
  • abnormal hemoglobin from birth that causes conditions like sickle cell anemia or thalassemia

Toxic anoxia

Toxic anoxia occurs when you take in toxins or other chemicals. This prevents your blood from effectively carrying oxygen throughout your body.

Carbon monoxide poisoning is one of the most common causes of toxic anoxia. Carbon monoxide is a produced when gas is used as fuel. A faulty gas stove, fireplace, or furnace can cause carbon monoxide to fill your home. It is also found in vehicle fumes.

Stagnant anoxia

Stagnant anoxia is also known as hypoxicischemic injury. It occurs when your blood doesn’t reach your brain or other body parts that need it. This can happen even when your blood is carrying plenty of oxygen and hemoglobin.

Cardiovascular events are the most common cause of stagnant anoxia. These include:

Anoxic anoxia

Anoxic anoxia happens when there’s not enough oxygen available to your body. If there isn’t enough oxygen to breathe in, you won’t be able to get enough oxygen to your bloodstream.

One form of anoxic anoxia can happen when you’re at high altitudes. Many of its symptoms are usually part of a condition called altitude sickness.

Exerting yourself when you’re at high altitudes can make the effects of anoxic anoxia worse. This is because with hard work, your body requires more oxygen but isn’t getting enough from the air.

You may develop anoxic anoxia when:

  • hiking
  • mountain climbing
  • skiing
  • snowboarding

Anoxic anoxia can also be caused by anything that keeps your lungs from working properly and limiting the body’s oxygen. These conditions include:

  • choking
  • suffocation
  • near drowning
  • breathing problems like asthma, pneumonia, or COPD
  • drug use

In order to find out if any symptoms you’re having are related to hypoxia or anoxia, your doctor may perform a variety of tests. Blood tests, imaging tests, and tests of your nervous system can all provide clues as to both the cause and results of hypoxia and anoxia.

Useful tests include:

  • magnetic resonance imaging (MRI) scan to see highly detailed images of your brain
  • functional magnetic resonance imaging (fMRI) scan to see how your brain reacts and functions during certain activities
  • computed tomography (CT) scan to see an overview of your brain
  • electroencephalogram (EEG), a test of your electrical brain activity
  • blood counts and blood gas tests that measure the levels of hemoglobin and oxygen in your blood
  • other brain testing that measures how you react to your environment

Treatment depends on how long your brain or other parts of your body have been deprived of oxygen.

If your brain doesn’t get enough oxygen for a few minutes or more, certain physical and mental functions can weaken. In most cases, your doctor will attempt to get your body and brain’s oxygen levels back to normal. This may include cardiopulmonary resuscitation (CPR) or putting you on a ventilator to get enough oxygen.

Your doctor may also treat certain symptoms, such as seizures, so that they don’t limit your recovery. If you’re able to receive care quickly after losing oxygen, you may not experience as many complications or long-lasting symptoms.

If a cardiac event or heart condition has caused anoxia, your doctor will treat you for these conditions or refer you to a heart specialist for further treatment.

Losing oxygen to your brain can cause permanent damage or loss in your ability to walk, talk, or perform basic functions.

In this case, your doctor will likely recommend that you get one or more of the following:

  • physical therapy to help restore your ability to walk and control your body
  • speech therapy to help restore your ability to speak and swallow
  • occupational therapy to help you adjust to activities of daily life
  • counseling to help you learn to cope with any changes to your life
  • recreational therapy to help promote health and wellness through individual and community activities like art, music, dance, games, and sports

There are specialized rehabilitation centers that work with individuals with brain injuries. Talk to your doctor about a referral to one of these centers in your area.

Hypoxic-anoxic brain injuries can cause long-lasting damage. The sooner that you recognize the symptoms of hypoxia and anoxia and seek treatment, the more likely that you’ll successfully recover from damage or complications of oxygen loss.

In some cases, your abilities may never be fully restored to your baseline. But many options are available for therapy and for support while you learn to manage your daily life after an anoxic injury. Talk to your doctor about the options available to you.

The goal of rehabilitation and therapy is to help you achieve the highest possible quality of life, regardless of what changes have occurred. You should try to be patient and stick with your care plan, as rehab and therapy are important and necessary tools for living a full, active, and healthy life.