What is anoxia?
Anoxia occurs when the brain is deprived of oxygen. It's often used interchangeably with hypoxia, although hypoxia refers to a partial loss of oxygen and happens first, typically leading to anoxia or a total lack of oxygen. In both cases, there is still adequate blood flow to the brain and bodily tissues.
Cells in the body die. This is part of a natural process called apoptosis. However, anoxia causes many neural cells to die at one time and can lead to anoxic brain injury.
Anoxia symptoms include:
- Problems focusing
- Memory loss
- Poor judgment
- Difficulties with motor coordination, including speech
- Visual disturbances
- Decrease of executive function, leading to poor decision making and impulsive behavior
Cells in the brain are sensitive and easily damaged. A lack of oxygen starves the brain and prevents biochemical processes that allow your brain, heart, and kidneys to function. Anoxia can result in coma, seizures, and brain death.
Types of anoxia
There are four main types of anoxia. Each has a different internal or external cause and varies in each person, but all have similar symptoms.
This type of anoxia affects a blood protein called hemoglobin, which delivers oxygen to your organs and tissues. When the body doesn't receive enough hemoglobin, your overall oxygen supply decreases.
When there isn't enough oxygen in the environment, you can experience anoxic anoxia. This can happen when you travel to higher altitudes, like hiking up a mountain. As you climb higher, the barometric pressure drops and there's less oxygen in the air, making breathing difficult. Anoxic anoxia also occurs when your lungs can't take in enough oxygen. This includes:
Also called a hypoxic-ischemic injury, stagnant anoxia occurs when blood can't reach the brain or other organs. Heart problems often cause this type of anoxia and may include:
Causes of anoxia include:
- High altitude exposure
- Inhaling carbon monoxide or heavy smoke
- Ingesting toxins or poisons
Diagnosis and tests for anoxia
A hypoxia diagnosis requires your doctor to check your blood’s oxygen levels. This can be done with a blood sample or an oxygen monitor that's placed on your finger.
If the cause of your hypoxia isn't clear, you'll undergo a series of lung function tests to measure how much air you inhale at once, how fast you can exhale, and how well your lungs deliver oxygen to your blood.
Treatment depends on what caused your symptoms. If you are unconscious or struggling to breathe, you will need basic life-support systems. This includes a ventilator to secure your airways, fluids, as well as blood pressure and heart rate medications to prevent seizures.
Recovering from hypoxia or anoxia depends on how long your brain was deprived of oxygen and how much brain damage occurred, although that may not be obvious for several weeks.
People who recover are usually only unconscious for a brief period of time. If you slip into a coma or remain unconscious for longer periods, it may cause significant brain damage or brain death.
As you're recovering, you may experience neurological and psychological changes like amnesia, memory loss, hallucinations, personality regression, and muscle spasms. These may appear and then resolve.
The recovery process for anoxic brain injury is long. You'll likely need physical therapy, speech therapy, counseling, as well as recreational and occupational therapy. It may require re-learning to walk, eat, and talk.
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Federal Aviation Administration (FAA): "Beware of Hypoxia."
National Institutes of Health: "Cerebral Hypoxia Information."
Shepherd Center: "Anoxic and Hypoxic Brain Injury."
Shepherd Center: "What are Anoxic or Hypoxic Brain Injuries?"
Temple Health: "Hypoxia Diagnosis."
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