When alveolar ventilation (V_A)is reduced from 5 L/minute to 2.5 L/minute,the Paco₂ changes from 40 mm Hg to:

Question

Quizplus · Accepted Answer

Alveolar ventilation is the amount of air that reaches the alveoli and participates in gas exchange. When alveolar ventilation is reduced, there is less gas exchange occurring, leading to an increase in the partial pressure of carbon dioxide (Paco2) in the blood. This is because carbon dioxide production continues at the same rate, but the removal of carbon dioxide from the body is reduced.

According to the alveolar gas equation, Paco2 is determined by the equation Paco2 = (FiCO2 x (Patm - PH2O)) / VA, where FiCO2 is the fraction of carbon dioxide in inspired air, Patm is the atmospheric pressure, PH2O is the partial pressure of water vapor in inspired air, and VA is alveolar ventilation.

Assuming the other variables remain constant, when alveolar ventilation is reduced from 5 L/minute to 2.5 L/minute, the Paco2 should theoretically double from 40 mm Hg to 80 mm Hg.

Therefore, the best choice is C) 80 mm Hg.

When Alveolar Ventilation (VA)is Reduced from 5 L/minute to 2

When Alveolar Ventilation (V_A)is Reduced from 5 L/minute to 2