HPV is a homeostatic mechanism that normally diverts blood flow away from hypoxic (atelectatic) regions of the lungs (local increases in pulmonary vascular resistance) and thereby optimizes oxygenation. Inhibition of HPV may cause or contribute to hypoxemia during anesthesia.
Effects of Anesthetics on Hypoxic Pulmonary Vasoconstriction. Clinical studies often fail to show a difference between inhaled and IV agents and an effect on HPV.