Question

what is the Po2 of inspired humidified air at the summit of mount Everest (assume atmospheric pressure is 247 mm Hg)

Answer 1

Atmospheric pressure and inspired oxygen pressure fall roughly linearly with altitude to be 50% of the sea level value at 5500 m and only 30% of the sea value value at 8900 m (the height of the summit of everest)

The peak of Mount Everest 8848m above sea level is the Highest point on the earth. The barometric pressure(PB) a peakis ~255mm Hg approximately one- third that at sea level and ambient partial pressure of oxygen is only~53mmHg.

For a climber At the peak of Mount Everest the Po2 of humidified insipired air entering the alveoli is even lower because of the effects of water vapour (PH2o = 47mm Hg at 37°c). Therefore the insipired Po2 is less than 149 mm Hg At sea level.

Hypoxia is the major problem at summit of Mount Everest

Calculation:

Inspired Po2= percentage of O2 (21%)× ( barometric pressure- partial pressure of water vapour)

Barometeric pressure = 247 mm Hg( given)

Partial pressure of water vapour = 47 mmHg

= 21%× ( 247-47)

= 21% × 200 mmHg

= 21/100 × 200 mmHg

= 21× 2mmHg

= 42mmHg