Abstract:
In 1944 the first recordings of pulmonary artery pressure (Ppa) in normal humans were published (6a). Dock (7), a Brooklyn physician, foresaw that in the upright position, with such a low Ppa, the upper quarter of the lung would be relatively ischemic in most people. He linked this notion to the apical (cranial) location of tuberculous lesions in humans in contrast to its caudal and dorsal distribution in quadrupeds and bats (8). Dock in 1947 did not consider a gradient of increasing blood flow below the bloodless apical regions; in 1960, West and Dollery (25) found a systematic increase in blood flow per unit volume from apex to base in the erect lung with a tenfold increase from top to bottom (Fig. 1). Apical blood flow increases at the onset of exercise and decreases when exercise stops (14), in keeping with the known increases and decreases in pulmonary artery pressure—further confirmation of Dock's reasoning.
