What is Hypoxia?
Hypoxia occurs when there is a lack of oxygen in the body. Hypoxia usually occurs at high altitudes under unpressurized situations and when supplemental oxygen is not available. Other factors that can contribute to hypoxia are alcohol, smoking, medical issues, and blood loss. There are four types of hypoxia: hypoxic hypoxia, stagnant hypoxia, hypemic hypoxia, and histotoxic hypoxia. The four types of hypoxia are determined by their cause.
Hypoxic Hypoxia:
Hypoxic hypoxia usually occurs at high altitudes when there is not enough oxygen in the air and when there is not enough atmospheric pressure to diffuse the oxygen from the lungs into the blood. At higher altitudes, there is still the same amount of oxygen in the air, but because of the reduced atmospheric pressure, the oxygen molecules are spread out.
Stagnant Hypoxia:
Stagnant Hypoxia occurs when there is enough oxygen-carrying capacity in the blood cells, but there is inadequate circulation of the blood. This type of hypoxia is fairly common. You have most likely experienced stagnant hypoxia when your “foot fell asleep”. Stagnant hypoxia can be caused by heart failure, arterial spasms and when the blood flow is disrupted.
Hypemic Hypoxia:
Hypemic Hypoxia is also known as anemic hypoxia. It is caused by a reduction in the blood’s oxygen carrying capabilities. In other words, the blood is unable to carry enough oxygen to the blood. The most common form of hypemic hypoxia is Carbon Monoxide (CO) poisoning. Severe bleeding can also cause hypemic hypoxia.
Histotoxic Hypoxia:
Histotoxic Hypoxia occurs when the cells are unable to use the oxygen provided to them. There is enough oxygen in the blood, but due to some type of impairment the cells cannot make use of the oxygen. Histotoxic hypoxia is usually caused by alcohol, drugs, and other compounds that can affect the cells.
Signs and Symptoms of Hypoxia:
Hypoxia can be identified by many different signs and symptoms. Common signs and symptoms include, but are not limited to:
- · Cyanosis (blue color in lips and fingertips)
- · Confusion
- · Poor judgment
- · Poor muscle coordination
- · Fatigue
- · Dizziness
- · Euphoria
- · Headache
- · Visual Impairment/Tunnel Vision
- · Tingling
How to Prevent Hypoxia
There are three main ways to prevent hypoxia. You should limit your time at high altitudes, use supplemental oxygen, and pressurize your cabin.
How to Treat Hypoxia
When you start experiencing the signs and symptoms of hypoxia or you notice somebody else exhibiting signs of hypoxia you should descend to a lower altitude (below 10,000 ft.). If supplemental oxygen is available onboard the aircraft, you should treat the individual with 100% oxygen.
Other Things Pilot’s Should Know:
How to Calculate Density and Pressure Altitude
Pilot’s Guide to Spatial Disorientation
Reference:
Pilot’s Handbook of Aeronautical Knowledge, FAA-H-80833-25A, 2008
