If the alveolar oxygenation is halved, the PACO2 will be

Ans: d (Halved in a few minutes) Ref: Ganong 22nd ed/ p.675, 21st ed/p.680When the alveolar oxygenation is halved, the resulting hypoxia will increase the respiratory rate (ventilation).This will lead to washing out of CO,. Since the effect on PACO, is due to increase in the respiratory rate, it will not occur immediately.There will be increase in respiratory rate only if the PO, drops from 100 to below 60 mm of Hg.