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Flashcards in Aeromedical: Hypoxia Deck (17):
1

Hypoxia

Hypoxia results when the body lacks oxygen.

Tends to be associated with flights at altitude.

However, other factors such as alcohol abuse, heavy smoking, & various medications interfere with the blood’s ability to carry oxygen

2

INDIVIDUALS PHYSIOLOGICAL ALTITUDE: Drugs

Many medications have an unexpected effect when combined with high altitudes.

Never self-medicate, even w/ over the counter drugs.

3

INDIVIDUALS PHYSIOLOGICAL ALTITUDE: Alcohol

1 oz of alcohol can give the body a physiological altitude up to 2000’.

4

INDIVIDUALS PHYSIOLOGICAL ALTITUDE: Smoking

The hemoglobin molecule of RBCs has a 200-300 times greater affinity for CO than for O2.

Smoking 3 cigarettes in rapid succession or 20 to 30 cigarettes w/ in a 24 hr period gives a physiological altitude of 5000’ at sea level & a 20% reduction of night vision.

5

Hypoxic Hypoxia

Occurs when not enough O2 is in the air or when decreasing atmospheric pressures prevent the diffusion of O2 from the lungs to the bloodstream.

Typically, Occurs at higher altitudes.

6

Hypemic Hypoxia

Is caused by a reduction in the oxygen-carrying capacity of the blood. Anemia & blood loss are the most common causes.

CO, nitrites, & sulfa drugs also cause this by forming compounds w/ hemoglobin & reducing the hemoglobin that is available to combine w/ O2.

7

Stagnant Hypoxia

O2 carrying capacity of the blood is adequate, but circulation is inadequate.

Conditions as heart failure, arterial spasm, & occlusion of a blood vessel predispose the individuals to stagnant hypoxia.

More often, a crew member experiences extreme gravitational forces, causing the blood to be stagnant.

8

Histotoxic Hypoxia

Results when there is interference with the use of O2 by body tissues.

Alcohol, narcotics, & certain poisons-cyanide- interfere the cell’s ability to use an adequate supply of oxygen.

9

Occurs when not enough O2 is in the air or when decreasing atmospheric pressures prevent the diffusion of O2 from the lungs to the bloodstream.

Typically, Occurs at higher altitudes.

Hypoxic Hypoxia

10

Is caused by a reduction in the oxygen-carrying capacity of the blood. Anemia & blood loss are the most common causes.

CO, nitrites, & sulfa drugs also cause this by forming compounds w/ hemoglobin & reducing the hemoglobin that is available to combine w/ O2.

Hypemic Hypoxia

11

O2 carrying capacity of the blood is adequate, but circulation is inadequate.

Conditions as heart failure, arterial spasm, & occlusion of a blood vessel predispose the individuals to stagnant hypoxia.

More often, a crew member experiences extreme gravitational forces, causing the blood to be stagnant.

Stagnant Hypoxia

12

Results when there is interference with the use of O2 by body tissues.

Alcohol, narcotics, & certain poisons-cyanide- interfere the cell’s ability to use an adequate supply of oxygen.

Histotoxic Hypoxia

13

Stages of Hypoxia: Indifferent

(0’ – 10,000’)

Night vision deteriorates at about 4000’.

When approaching 10,000’ visual acuity begins to decrease.

14

Stages of Hypoxia: Compensatory

10,000’ – 15,000’

The circulatory & the respiratory system provide some defense against hypoxia at this stage.

The pulse rate, systolic blood pressure, circulation rate, & cardiac output increase. Respiration increases in depth & sometimes in rate.

At 12,000’ to 15,000’ the effects of hypoxia on the nervous system become increasingly apparent.

After 10-15 min, impaired efficiency is obvious.

Crew members may become drowsy & make frequent errors in judgment.

May become difficult to do even simple task. Easy to overlook these symptoms. 

15

Stages of Hypoxia: Disturbance

(15,000’ – 20,000’)

  • The physiological responses can no longer compensate for the O2 deficiency.
  • Subjective symptoms include: fatigue, sleepiness, dizziness, headache, breathlessness, & euphoria.
  • Objective symptoms include: Senses: peripheral & central vision are impaired, & visual acuity is diminished. Weakness & loss of muscular coordination are experienced. Sensations of touch & pain are diminished or lost. Hearing is one of the last senses lost. 
  • Mental Processes: Intellectual impairment is an early sign that often prevents the individual from recognizing disabilities. Thinking is slow, & calculations are unreliable. Short-term memory is poor, & judgment & reaction time is affected.

  • Personality Traits: Person may display traits & emotions much the same as with intoxication. Euphoria, aggressiveness, overconfidence, or depression can occur.

  • Psychomotor Functions: Muscular coordination is decreased, & delicate or fine muscular movements may be impossible. Stammering & illegible handwriting are typical impairments. 

  • Cyanosis: the skin becomes bluish in color. This effect is caused by O2 molecules failing to attach to hemoglobin molecules.

16

Stages of Hypoxia: Critical

(20,000’ and above)

  • Within 3 to 5 minutes, judgment, & coordination usually deteriorate.
  • Subsequently, mental confusion, dizziness, incapacitation, & unconsciousness occur.

17

______ _____ is the type most often encountered in aviation.

Hypoxic hypoxia

Education is the greatest prevention.