What is hypoxia?

Hypoxia is a deficiency of oxygen in body tissue.

Hypoxia is dangerous as this condition reduces mental function.  The primary causes of hypoxia are insufficient supply of oxygen, inadequate transportation of oxygen or inability of the body to use oxygen.  The four types of hypoxia are: hypoxic hypoxia, hypemic hypoxia, stagnant hypoxia and histotoxic hypoxia.

Hypoxic hypoxia is a result of insufficient oxygen available to the body as a whole.  Hypoxic hypoxia can occur with reduction in partial pressure of oxygen at high altitude.

Hypemic hypoxia occurs when the blood is not able to take up and transport a sufficient amount of oxygen to the cells in the body.  Hyperemic hypoxia may be caused by a variety of factors, such as lack of blood due to severe bleeding or diseases such as anemia.  The most common form of hypemic hypoxia is carbon monoxide poisoning, which prevents the blood’s hemoglobin from binding with and transporting the oxygen.

Stagnant hypoxia results when the oxygen-rich blood in the lungs is not moving adequately.  Stagnant hypoxia can occur with excessive acceleration of gravity or g forces.

Histotoxic hypoxia is the inability of the cells to effectively use oxygen.  Alcohol and other drugs can impair the body’s ability to use oxygen and can lead to histotoxic hypoxia.

Symptoms of hypoxia include cyanosis, headache, decreased response to stimuli and increased reaction time, impaired judgment, euphoria, visual impairment, drowsiness, dizziness, tingling in fingers and toes and numbness.  Treatment for hypoxia includes flying at lower altitudes and/or using supplemental oxygen.

Reference(s):

FAA-H-8083-25B Pilots Handbook of Aeronautical Knowledge pg. 17-3

Other Aeromedical Factors

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