A patient breathing room air at sea level has the following arterial blood gases: PaO₂ = 62 mm Hg; PCO₂ = 75 mm Hg. When the FIO₂ is raised to 0.28, the PaO₂ rises to 95 mm Hg. What is the most likely cause of the hypoxemia?

Question

Quizplus · Accepted Answer

The most likely cause of the hypoxemia is hypoventilation, as indicated by the initial high PCO2 (indicating retention of CO2 due to inadequate ventilation) and the significant improvement in PaO2 with increased FiO2, which would not occur if the primary issue was a right-to-left shunt or severely impaired diffusion.

A Patient Breathing Room Air at Sea Level Has the Following