See text for discussion. The important point is that hyperventilation in some units can compensate for the tendency of hypoventilated units to increase the PCO 2 . Such patients are unable to sustain the necessary increase in minute ventilation. Such a patient must maintain an increased minute ventilation to maintain a normal PaCO 2 . The most common physiologic cause of hypoxemia is diffusion barrier.
Thebesian vessels supply the myocardium and drain the venous blood directly into the ventricles.
Hemodialysis can lead to hypoxemia by reducing alveolar ventilation. Arterial oxygenation during hemodialysis, N. Engl. Harris, E.A., Kenyon, A.M., Nisbet, H.D., et al. Mechanisms producing hypoxemia during hemodialysis, Crit. Positional hypoxemia in unilateral lung disease, N. Engl.