Hypoxia

Question 1

Hypoxia definition

Answer 1

Hypoxia is where the body is deprived of oxygen

Question 2

Partial pressure of oxygen at sea level in the atmosphere

Answer 2

160 mmHg

Question 3

Partial pressure of oxygen at sea level in alveoli

Answer 3

104 mmHg

Question 4

Partial pressure of oxygen at sea level in venus blood

Answer 4

30 - 40 mmHg

Question 5

Partial pressure of oxygen at sea level in arterial blood

Answer 5

75 - 100mmHg

Question 6

Explain the mechanical effect of the partial pressure of oxygen on oxygen transfer in the lungs.

Answer 6

Partial pressure of oxygen is high in the alveoli and low in the blood of the pulmonary capillaries. As a result, oxygen diffuses across the respiratory membrane from the alveoli into the blood.

Question 7

Causes of hypoxia

Answer 7

Insufficient supply / transportation of oxygen or inability of the body to use oxygen

Question 8

Symptoms of hypoxia

Answer 8

• Cyanosis (blue fingernails and lips)
• Headache
• Decreased reaction time
• Euphoria
• Drowsiness
• Dizziness
• Numbness
• Impaired judgement
• Visual impairment
• Lightheadedness
• Tingling in fingers and toes

Question 9

Why is hypoxia is often difficult to detect

Answer 9

As some symptoms such as euphoria give the pilot a false sense of security and so they think that everything is normal

Question 10

Explain the relationship between hypoxic onset and both vision and cognitive
performance.

Answer 10

Vision is the first of the senses to be affected by a lack of oxygen. This is especially true of night vision, which may be affected as low as 5,000 ft of altitude. Colour vision starts to deteriorate between 5,000 - 10,000 ft. At higher altitudes, the ocular muscles become weakened and uncoordinated. The range of accommodation is decreased which causes blurring of near vision and subsequently difficulty in carrying out near-vision-related tasks. Above 10,000 ft the visual disturbances are more severe as reaction time and responses to visual stimuli become sluggish. Accommodation and convergence are weakened and cause double vision. All problems, however, can usually be reversed by the use of oxygen or a return to sea level.

Question 11

Hypoxia prevention

Answer 11

Avoiding circumstances that reduce oxygen concentration in the environments or by providing oxygen before symptoms develop

Question 12

Factors that affect the onset and severity of hypoxia

Answer 12

• Individual’s physical fitness
• Cabin temperature
• Altitude
• Rate of ascent
• Duration at altitude
• g maneuvers can also cause blood to pool in lower limbs affecting circulation of oxygenated blood

Question 13

Treatment of hypoxia

Answer 13

Using supplemental oxygen and flying at lower altitudes