Abstract
The postural effect of lateral decubitus position on the distribution of pulmonary arterial blood flow was assessed in 9 normal subjects and 31 patients with pulmonary tuberculosis by radioisotope perfusion scanning of the lungs. The perfusion of the dependent lung was larger than that of the supine lung with out exception. In both normal and tuberculous subjects, the average overall ratio of the pulmonary arterial blood flow in the dependent lung was 1.1 to 1.2 times that of the supine lung in any of the right and left lateral decubitus positions, and this was assumed to be due to gravitational effect. It was clarified that the increase in oxygen uptake in the dependent lung so far reported by many investigators was due to increased distribution of the pulmonary arterial blood flow which was related to gravitational effect.
