Relationship of pulmonary artery pressure to exercise diffusing capacity (DLco)

Abstract

We investigated the importance of pulmonary artery pressure (Ppa) and pulmonary blood flow PBF) in determining the increase in Dlcco observed during exercise. In 13 anesthetized dogs, an external right atrial reservoir was connected via a large-bore jugular vein catheter. Ppa, 10-sec-breath-holding Dlco, and PBF were measured during electrically induced exercise. Subsequent measurements were made during similar exercise while Ppa increases were prevented by varying the atrial reservoir level. In the control exercise situation, Dlco increased from 13.6 ± 6.4 at rest to 24.4 ± 9.2 ml/min x mm Hg; PBF from 3.68 ± 1.78 to 7.09 ± 2.82 liters/min; Ppa from 11 ± 4 to 23 ± 8 mm Hg; and O2 consumption from 131 ± 37 to 529 ± 249 ml/min. When Ppa was maintained at resting level during exercise sufficient to produce similar increases in O2 consumption, Dlco did not rise. This study shows: 1) exercise Dlco increases can be prevented if the Ppa increase is prevented; 2) an excellent statistical correlation between increased Dlco and increased Ppa during exercise but a similar correlation between increased PBF and increased Dlco was not established. pulmonary diffusing capacity; Dl with exercise in dogs Submitted on December 13, 1968