PULMONARY VASCULAR TONE AND THE ANESTHESIOLOGIST

The lung is the necessary link in transporting oxygen from the air to the blood. In this process, the pulmonary capillaries provide the critical air-blood interface. The thinness of the pulmonary capillary wall is conducive to fluid leakage and pulmonary edema, which could impair oxygenation of the blood. The pulmonary capillaries must maintain adequate perfusion, but it is essential that the perfusion is regulated so that gas exchange is not impaired by excessive fluid leakage. This balance is achieved by modulation of pulmonary vascular resistance (PVR), which is brought about by changes in vascular smooth muscle tone in the pulmonary arterioles.