what causes hypoxemia in pulmonary edema
Four Causes of Hypoxemia Figure 3 nicely illustrates the relationship between PAO2 and PACO2 as the V/Q ratio is changed. From JB West, Pulmonary Physiology-The Essentials, 7th ed. V/Q imbalance is the most common cause of hypoxemia, a result of lung units with low V/Q ratios. An extreme case is easy to grasp â the left lung gets all the ventilation and no blood flow; the right lung gets no ventilation and all the blood flow. In this case, you have a big dead space and a big shunt. Four Causes of Hypoxemia I. Hypoventilation: Hypoxemia develops when the pulmonary alveoli are inadequately ventilated. Clinically, the hallmark of inadequate ventilation is hypercapnia, an elevated systemic arterial PCO2 (PaCO2 > 43 mm Hg). The most common cause of hypoventilation is depression of the medullary respiratory center by drugs.