The Distribution of Pulmonary Blood Flow in the Upright Position

(Reproduced with permission from Slinger P. Principles and Practice of Anesthesia for Thoracic Surgery. New York, NY: Springer; 2011.)

A. Pulmonary blood flow as affected by gravity and alveolar pressure. This classic description based on the work of West divides pulmonary blood flow into four zones. PA, alveolar pressure; Ppa, pulmonary arteriolar pressure; Ppv, pulmonary venous pressure; Pisf, pulmonary interstitial pressure. B. Subsequent investigations with lung scanning have shown that blood flow is actually distributed more in a central to peripheral pattern.