Regional distribution of pulmonary blood flow in normal high-altitude dwellers at 3,650 m (12,200 ft).

Simultaneous isotope dilution curves were recorded from the right upper (QRUZ) and right lower lung zones (QRLZ) by surface scanning in the sitting and recumbent positions in 15 normal high-altitude-born (HAD) males and in 1 HAD female as well as from 3 male newcomers, using 10 muCi of 131I-HSA as a bolus injection into the right ventricle. Similar information was also obtained at sea level from 5 normal males. The mean percent distribution of total pulmonary blood flow (Q) to RUZ and RLZ in the two body postures indicate (1) that in the vertical position RUZ in males receives about 17% of Q regardless of altitude and elevation in mean pulmonary artery pressure (MPAP) in HAD of 8.6 mm Hg above that extant at sea level; (2) recumbency at high altitude showed QRUZ also to be lower than at sea level; (3) elevation in MPAP at altitude has no significant effect on changing the sea-level distribution pattern of pulmonary blood flow.