Effect of pulmonary vascular engorgement on Dl during and immediately after exercise

¹ Department of Medicine and Heart Research Center, Indiana University School of Medicine, Indianapolis, Indiana

Pulmonary diffusing capacity (Dl) is increased more markedly by moderate exercise, which causes little increase in pulmonary vascular pressure, than by inflation of a pressure suit over the lower part of the body, which produces pulmonary vascular engorgement and marked increases in pulmonary pressure. This study was designed to determine whether exercise causes the pulmonary capillary bed to be more permissive to passive dilatation. Dl was determined in 12 subjects before, during, and soon after a period of exercise with and without the pressure suit inflated. Dl was increased in resting subjects by suit inflation, but less than with exercise. Exercise with suit inflation did not increase Dl more than exercise alone. Suit inflation 3 min after exercise ended, however, increased Dl to higher levels than at any other time with suit inflation alone. The pulmonary capillary bed apparently cannot be further dilated by vascular engorgement during exercise beyond that caused by exercise alone. Also, soon after exercise ends, the pulmonary capillary bed is more permissive to passive dilatation by vascular engorgement with suit inflation.

Submitted on June 17, 1963