The Venous Pump in the Legs as a Determinant of Pulmonary Capillary Filling*

Journal/Book: Journal of Clinical Investigation Vol. 44 No. 2 1965. 1965;

Abstract: From the Department of Medicine and the Heart Research Center Indiana University School of Medicine Indianapolis Ind. * Submitted for publication July 20 1964; accepted October 29 1964. This study was supported in part by research grants H6228 and H4080 from the National Heart Institute and in part by U. S. Air Force contract 33(616)8378. This work was done during tenure of a U. S. Public Health Service postdoctoral research fellowship. Summary Passive motion of the lower extremities in upright normal men decreases the pressure in the saphenous vein at the ankle and increases breath-holding diffusing capacity (DLCO). This effect is present in the first 10 seconds of passive leg motion. DLco does not increase during passive motion of the legs in sitting subjects if the egress of blood from the legs is prevented by the inflation of thigh tourniquets to 250 mm Hg or in supine subjects. This study suggests that a portion of the increase in DLCO that occurs with exercise in an upright position is dependent upon pumping of blood from the exercising part to the lung and is independent of any generalized reflex action. It suggests further that the venous pumping mechanism is one of the determinants of pulmonary capillary filling in upright postures. ___MH

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