A patient has a normal oxygen partial pressure and content in pulmonary venous blood but his systemic arterial blood shows a significantly lower than normal oxygen partial pressure and content. This is diagnostic of which of the following?
A)Diffusion limitation
B)Right-to-left shunt
C)Pulmonary ventilation/perfusion nonuniformity
D)Stagnant hypoxia (low cardiac output)

Question

Quizplus · Accepted Answer

A right-to-left shunt is the only option that would result in normal oxygenation of blood in the pulmonary veins (which bypasses the shunt) but decreased oxygenation in the systemic arterial blood. Diffusion limitation, pulmonary ventilation/perfusion nonuniformity, and stagnant hypoxia would all affect both pulmonary venous and systemic arterial oxygen levels.

A Patient Has a Normal Oxygen Partial Pressure and Content