Effect of pressure-suit inflation on pulmonary-diffusing capacity

¹ Cardiopulmonary Laboratory, Medical Service, Veterans Administration Hospital; and Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana

Pressure-suit inflation over the lower body produces acute pulmonary hypertension. An increase in pulmonary capillary blood volume, Vc, with this procedure should theoretically increase pulmonary-diffusing capacity, Dl. Lewis and co-workers (J. Appl. Physiol. 12:57, 1958) found no increase in Dl with suit inflation. The subject was reinvestigated with measurement of the increase in central venous pressure, CVP, produced and with a study of effect of alveolar volume, Va, and the Valsalva maneuver on the results. Dl was determined in five seated and seven supine subjects at small and large Va, both before and during suit inflation and also with a Valsalva under each condition. Suit inflation significantly increased Dl (13%) with an increase in 21 of the 22 comparisons. Mean Dl was 16% lower when Va was decreased 34%. The Valsalva maneuver significantly decreased both control and suit inflation Dl. Results show that with controlled Va and no Valsalva and when CVP was definitely increased by the procedure, Dl significantly increased with suit inflation, probably indicating that the pulmonary capillary bed was passively dilated.

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