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WHAT IS HYPOXIA?
The result of a lack of Oxygen in the body. This is caused by flight at high altitudes, smoking, and other factors. There are 4 types or conditions of Hypoxia.
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What are 4 types or conditions of Hypoxia?
Hypoxic, Hypemic, Histotoxic, Stagnant
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What are the defintions of the 4 types of Hypoxia?
- HYPOXIC- Results from an INSUFFICIENT amount of oxygen in the air.
- HYPEMIC- Reduction in the OXYGEN CARRYING CAPACITY of the blood. Examples are; Anemia, Blood Loss, Carbon Monoxide (smoking), nitrates, Sulfa Drugs.
- HISTOTOXIC- Results from INTERFERENCE with the use of oxygen by the body. Examples are; Alcohol, Narcotics, & poisons.
- STAGNANT- Results from INADEQUATE CIRCULATION of blood, which for aviators is common in G Forces. Other examples are; Heart Failure, Arterial Spasms, Vessel Occlusions.
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PHYSIOLOGICAL ALTITUDES OF HYPOXIA
The altitude that the body feels due to stressors applied to it. The 2 types of stressors that cause a physiological altitude are smoking and alcohol.
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PHYSIOLOGICAL STRESSORS
- SMOKING- Smoking 3 cigarettes in rapid succession or 20 – 30 (pack – pack ½) in 24 hours can saturate 8-10% of the Hemoglobin in blood reducing oxygen carrying capacity (Hypemic) resulting in;
- * Loss of 20% of night vision at sea-level
- * Physiological altitude of 5,000’ at sea-level
- The results of this Physiological Altitude would mean that at an aircraft altitude of 5,000’ - 6,000’ (common under IFR), where the rest of the crew were in the Indifferent Stage, a smoker under the conditions above would be in the Compensatory Stage.
- ALCOHOL- 1 ounce (shot) of alcohol creates Histotoxic Hypoxia and a resulting Physiological Altitude of 2,000’ at sea-level.
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Four stages of Hypoxia
- Compensatory
- 10,000 – 15,000’
- Disturbance-
- 15,000 – 20,000’
- Critical-
- 20,000 – 25,000’
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Symptoms of 4 stages of Hypoxia
- INDIFFERENT- Decrease in Night Vision.
- (Normal operating environment for Rotary Wing)
COMPENSATORY- Drowsiness, Poor Judgment, Impaired Coordination, Impaired Efficiency.
- DISTURBANCE-
- IMPAIRED FUNCTIONS: Flight Control, Handwriting, Speech, Vision, Intellectual Function, Judgment.
- DECREASED FUNCTIONS: Coordination, Pain Sensation, Memory.
CRITICAL- Circulatory Failure, CNS Failure, Convulsions, Cardiovascular Collapse, DEATH.
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