EFFECT OF POSTURE ON VENOUS VELOCITY, MEASURED WITH 24NaCl

Abstract

The importance of posture in the venous return to the heart from the lower limbs in normal and pathological conditions has been recognized for over a century. As early as 1826, Piorry noted that the effect of gravity could produce syncope in subjects kept in the upright posture and that the attack was relieved when the patient lay down. Marshall Hall (1832) carried out animal experi- ments which showed that the venous return was, to a great extent, dependent upon posture and that the blood in the limbs was directly controlled by gravity. In man, a clue to the mechanism whereby blood is propelled from the lower limbs against the force of gravity is given by the presence of valves in the veins, an adaptation unnecessary in animals that have not assumed the upright gait.