Hypoxia Flashcards
Hypoxia definition
Hypoxia is where the body is deprived of oxygen
Partial pressure of oxygen at sea level in the atmosphere
160 mmHg
Partial pressure of oxygen at sea level in alveoli
104 mmHg
Partial pressure of oxygen at sea level in venus blood
30 - 40 mmHg
Partial pressure of oxygen at sea level in arterial blood
75 - 100mmHg
Explain the mechanical effect of the partial pressure of oxygen on oxygen transfer in the lungs.
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.
Causes of hypoxia
Insufficient supply / transportation of oxygen or inability of the body to use oxygen
Symptoms of hypoxia
- Cyanosis (blue fingernails and lips)
- Headache
- Decreased reaction time
- Euphoria
- Drowsiness
- Dizziness
- Numbness
- Impaired judgement
- Visual impairment
- Lightheadedness
- Tingling in fingers and toes
Why is hypoxia is often difficult to detect
As some symptoms such as euphoria give the pilot a false sense of security and so they think that everything is normal
Explain the relationship between hypoxic onset and both vision and cognitive
performance.
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.
Hypoxia prevention
Avoiding circumstances that reduce oxygen concentration in the environments or by providing oxygen before symptoms develop
Factors that affect the onset and severity of hypoxia
- 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
Treatment of hypoxia
Using supplemental oxygen and flying at lower altitudes