Influence of Hematocritcomma Blood Gas Tensions, and pH on Pressure-Flow Relations in the Isolated Canine Lung

An isolated perfused canine lung preparation in which determinants of vascular caliber could be individually controlled was developed. The relation of pulmonary arterial (Pa), venous (Pv), and alveolar (PA) pressures was such that Pa > PA > Pv throughout the whole lung. The addition of isopren...

Full description

Saved in:

Bibliographic Details
Published in:	Circulation research Vol. 37; no. 5; pp. 588 - 596
Main Authors:	Bucens, Daumants, Pain, Michael C. F
Format:	Journal Article
Language:	English
Published:	American Heart Association, Inc 01-11-1975
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	An isolated perfused canine lung preparation in which determinants of vascular caliber could be individually controlled was developed. The relation of pulmonary arterial (Pa), venous (Pv), and alveolar (PA) pressures was such that Pa > PA > Pv throughout the whole lung. The addition of isoprenaline to the perfusate abolished vascular reactivity. Once stability was reached, vascular cross-sectional area remained acceptably constant for 2.25 hours as judged by normalized conductance. The influence of perfusate hematocrit, blood gas tensions, and pH on pressure-flow relations was then studied in 15 isolated canine lungs. The hematocrit-vascular conductance relation was derived at constant perfusion pressure. Conductance varied linearly with hematocrit over a range of 16.5 to 89.5percent. Mean pulmonary arterial blood gas tensions werePo2 = 121 mm Hg, Pco2 = 28 mm Hg, and pH = 7.46. Acute respiratory acidosis (Po2 = 30 mm Hg, Pco2 = 81 mm Hg, pH = 7.17) and lactic acidosis and hypoxemia (Po2 = 32 mm Hg, Pco2 = 21 mm Hg, pH = 6.96) did not significantly alter this relation. Transformation of the conductance-hematocrit data indicated that hematocrit was the most important determinant of relative apparent viscosity of the blood. Both acute respiratory and lactic acidosis failed to significantly increase relative viscosity within the range of hematocrit usually found in secondary polycythemia.
ISSN:	0009-7330 1524-4571