Extreme Conditions

Question 1

What is extremely high altitude classed as?

Answer 1

18,000 feet

Question 2

Give the alveolar gas equation.

Answer 2

PAO2 = PiO2 - PaCO2/R

R = respiratory quotient

Question 3

What is the relationship between PaCO2 and 1/alveolar ventilation?

Answer 3

They are directly proportional.

Question 4

What is atmospheric pressure at sea level (0m)?

Answer 4

100kPa

Question 5

Does FiO2 remain constant at varying altitudes?

Answer 5

Yes. Always remains at 0.21

Question 6

What happens to pressure as altitude rises?

Answer 6

Pressure decreases.

Question 7

What is the effect of increasing altitude on the lungs?

Answer 7

• hypoxia leads to hyperventilation
• increased minute ventilation
• respiratory alkalosis (later compensated for by renal bicarbonate excretion)

Question 8

Describe 2 high altitude illnesses.

Answer 8

1. Acute mountain sickness
   - ascent over 2500m
   - headache + lethargy, shortness of breath
   - can only be treated with descent
2. High altitude pulmonary oedema
   - rapid ascent
   - affects unacclimatised people
   - treat with oxygen and descent

Question 9

For every 10m of depth in water, how does the pressure change?

Answer 9

For every 10m, pressure increases by 1atm. Remember at 0m, pressure is 1atm.

Question 10

What is decompression illness?

Answer 10

When you ascend in water at a rate that exceeds body’s capacity. Causes inert bubbles to form in tissues.