Pilot Physiology

HYPOXIA-

Hypoxia is a lack of oxygen at the tissue level of the body due to a decrease of oxygen pressure in inspired air or because of conditions that interfere with the diffusion or absorption of oxygen within the body.

Types of Hypoxia

Histotoxic Hypoxia- Interference of the tissue’s ability to absorb or metabolize delivered oxygen. This is often caused by alcohol, narcotics or poisons.

Hypemic Hypoxia- Reduction of the blood’s ability to carry oxygen. Carbon monoxide is the most common cause followed by anemia, blood loss and smoking.

Hypoxic Hypoxia- Lack of oxygen in the tissues due to decrease in the partial pressure of oxygen at altitude.

Causes of Hypoxia
1. Flight at an altitude where there is insufficient partial pressure of oxygen
    to cause oxygen transfer.
2. Ingestion or inspiration of drugs that interfere with the blood’s ability to
    Absorb or transport oxygen from the lungs to the cells.
3. Malfunction of the circulatory system.
4. Positive "g" forces preventing oxygenated blood from reaching the brain.
5. Mechanical malfunction of supplemental oxygen equipment.

Symptoms of Hypoxia
1. Decreased visual acuity
2. Mental confusion
3. Shallow, rapid breathing
4. Cyanosis of the fingernails
5. Headache
6. Eventual incapacitation, followed by death.

Prevention of Hypoxia
1. Use lowest practical flight level.
2. Minimize duration of high altitude operations.
3. Allow acclimatization to higher altitudes
4. Refrain from alcohol and tobacco products.
5. Maintain good physical condition.
6. Use supplemental oxygen when necessary and when required by FARs.

Supplemental Oxygen
1. Required for crew members when flying between 12,500 and 14,000 MSL for
    over 30 minutes.
2. Required for crew members at all times when flying above 14,000 MSL.
3. Must be provided for passengers above 15,000 MSL.
4. Will have beneficial effect at altitudes well below those required by FAR.

IMPORTANT NOTE: WHILE THE REGULATIONS REQUIRE USE OF OXYGEN IN TERMS OF ABSOLUTE ALTITUDE, THE PHYSIOLOGICAL EFFECTS OF HYPOXIS RESULT FROM DENSITY ALTITUDE. BASE YOUR DECISIONS REGARDING EXPOSURE TO HYPOZIS ON YOUR CALCULATIONS OF THE DENSITY ALTITUDE AT WHICH YOU ARE OPERATING.

Sinus Pressure
1. Close your mouth and keep it closed.
2. Pinch your nostrils closed tightly.
3. Force your tongue against the roof of your mouth.
4. Exhale forcibly through the upper throat into your nasal cavity until the pressure is        equalized.

Ultraviolet Radiation
1. Thin air at higher altitudes allows more damaging UV radiation from the sun to
    reach the cockpit.
2. Protect exposed skin with sunscreen.
3. Wear sunglasses which block both UV-A and UV-B radiation.

Personal Equipment
1. Wear layers of warm clothing in the winter months.
    Aircraft heater may be ineffective or inoperative.
    Heater may not distribute air evenly throughout the aircraft.
    May be all you retain following a rapid egress from aircraft.
2. Drink water to prevent dehydration.
3. Augment normal aircraft survival gear.
    Mountain become very cold at night, even in the summer.
    Sleeping bag can be a lifesaver, especially if injured.
    High calorie food necessary in low temperature environment.
    Traveling for water or shelter can be difficult in steep terrain.