Hypoxia

✍️ #HYPOXIA

Hypoxia results when the body lacks oxygen. It generally is associated with flights at high altitude. Other factors such as alcohol abuse, heavy smoking, and various medications can interfere with blood's ability to carry and absorb oxygen, reducing the body's tolerance to hypoxia.

✍️4 TYPES OF HYPOXIA

STAGNANT

HYPOXIC

HYPEMIC

HISTOTOXIC

✍️STAGNANT HYPOXIA

With stagnant hypoxia, blood's oxygen-carrying capacity is adequate but circulation is inadequate. Conditions like heart failure, arterial spasm, and blood vessel occlusion predispose affected individuals to stagnant hypoxia. This type of hypoxia often occurs when a crewmember experiences extreme gravitational forces and blood flow is disrupted, causing blood to stagnate.

✍️HYPOXIC HYPOXIA

Hypoxic hypoxia occurs when there is not enough oxygen in the air or when decreasing atmospheric pressure prevents diffusion of oxygen from the lungs to the bloodstream. Aviation personnel are most likely to encounter this type of hypoxia at high altitudes due to the reduction of PO2 in the atmosphere.

✍️HYPEMIC HYPOXIA

Hypemic, or anemic, hypoxia is caused by a reduction in blood's oxygen-carrying capacity. Anemia and blood loss are the most common causes of this type of hypoxia. Other possible causes include exposure to carbon monoxide, nitrites, and sulfa drugs, which form compounds with and reduce the amount of hemoglobin available to combine with oxygen.

✍️HISTOTOXIC HYPOXIA

Histotoxic hypoxia results from an interference with the use of oxygen by body tissues. Alcohol, narcotics, and certain poisons such as cyanide interfere with a cell's ability to use an adequate supply of oxygen.

✍️SIGNS OF HYPOXIA

observed by others therefore are considered objective.

Hyperventilation

Cyanosis

Mental confusion

Poor judgment

Lack of muscle coordination

✍️SYMPTOMS OF HYPOXIA

Felt by the person and may vary. Considered subjective.

Apprehension

Belligerence

Blurred vision

Dizziness

Euphoria

Fatigue

Headache

Hot and cold flashes Tingling

Increased breathing rate

Numbness

Tunnel vision

✍️SUSCEPTIBILITY TO HYPOXIA

Ambient Temperature

Ascent Rate

Exposure Duration

Individual Factors

Onset Time and Severity

Physiological Altitude

✍️STAGES OF HYPOXIC HYPOXIA

(ICDC)

INDIFFERENT

COMPENSATORY

DISTURBANCE

CRITICAL

✍️INDIFFERENT STAGE

Mild hypoxia in the indifferent stage causes night vision to deteriorate at about 4,000 feet. Crewmembers who fly above 4,000 feet at night should be aware that visual acuity decreases significantly in this stage due to dark conditions and the development of mild hypoxia.(98%-90% oxygen saturation)

COMPENSATORY STAGE

The circulatory system and, to a lesser degree, the respiratory system provide some defense against hypoxia at the compensatory stage. Pulse rate, systolic blood pressure, circulation rate, and cardiac output increase. Respiration increases in depth and sometimes in rate. At 12,000 feet to 15,000 feet, the effects of hypoxia on the nervous system become increasingly apparent. After 10 to 15 minutes, impaired efficiency is obvious. Crewmembers might become drowsy and make frequent errors in judgment. They might also find it difficult to perform even simple tasks requiring alertness or moderate muscular coordination. Crewmembers preoccupied with duties can easily overlook hypoxia at this stage.

✍️DISTURBANCE STAGE

In the disturbance stage, physiological responses can no longer compensate for oxygen deficiency. Occasionally, crewmembers can become unconscious from hypoxia without undergoing the subjective symptoms described in table 2-7. Fatigue, sleepiness, dizziness, headache, breathlessness, and euphoria are the symptoms most often reported at this stage. Other symptoms include—

Loss of Senses. Peripheral vision and central vision are impaired, and visual acuity is diminished. Weakness and loss of muscular coordination are experienced. The sensations of

touch and pain are diminished or lost. Hearing is one of the last senses to be lost.

Reduced Mental Processes. Intellectual impairment is an early sign that often prevents an individual from recognizing disabilities. Thinking is slowed, and calculations are unreliable. Short-term memory is poor, and judgment—as well as reaction time—is affected.

*Unusual Personality Traits. There might be a display of basic personality traits and emotions much the same as with alcoholic intoxication. Euphoria, aggressiveness, overconfidence, or depression can occur.

*Reduced Psychomotor Functions. Muscular coordination is decreased, and delicate or fine muscular movements might be impossible to complete. Stammering and illegible handwriting are typical of hypoxic impairment.

*Cyanosis. When cyanosis occurs, the skin becomes bluish in color. This effect is caused by oxygen molecules failing to attach to hemoglobin molecules.

✍️CRITICAL STAGE

Within 3 to 5 minutes without oxygen, judgment and coordination usually deteriorate. Mental confusion, dizziness, incapacitation, and unconsciousness subsequently occur.

✍️PREVENTION OF HYPOXIC HYPOXIA

PRESSURIZING THE CABIN

USING SUPPLEMENTAL OXYGEN

LIMITING TIME AT ALTITUDE

✍️TREATMENT OF HYPOXIA

100 OXYGEN

DESCEND BELOW 10K FT

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