As the barometric pressure increases, there is an increase in the ...

[ARLKQ]

As the barometric pressure increases, there is an increase in the density of the gas being breathed. The increase in gas density in turn causes a(n):
 
  a. Decrease in work of breathing c. Increase in work of breathing
  b. Increase in FIO2 d. Decrease in FIO2

Question 2

A patient is receiving 0.30 FIO2 with a barometric pressure at 750 mm Hg. The partial pressure of carbon dioxide (PCO2) for this patient is 70 mm Hg; the partial pressure of arterial oxygen (PaO2) is 60 mm Hg. The PAO2 for this patient is _____ mm Hg.
 
  a. 100.2 c. 160.0
  b. 123.4 d. 181.7

[millet]

Answer to Question 1

ANS: C
The increase in gas density results in increased work of breathing, which is not noticeable and can easily be accommodated in healthy subjects. In patients with reduced lung reserves, however, this increased work can present problems and necessitate ventilatory support.

Answer to Question 2

ANS: B
Formula: PAO2 = (Barometric pressure PB  pressure of water vapor PH2O) FIO2  PaCO2 (1.25).
PAO2 = (750 mm Hg  47) 0.30  70 (1.25).
PAO2 = 210.9  87.5.
PAO2 = 123.4 mm Hg.

[ARLKQ]

TYSM

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