The Loss of Fluid and Protein From the Blood During a Systemic Rise of Venous Pressure Produced by Repeated Valsalva Maneuvers in Man1

Abstract
In healthy subjects, the effect of sustained elevation of venous pressure, 11-21 cm H2O above normal, (accomplished by repeated Valsalva maneuvers, made in a manner similar to that observed during obstetric labor) on blood volume was studied, by means of changes in venous hematocrit, plasma protein and T-1824 concentrations. The initial loss of fluid is rapid amounting to 3 to 10% of blood volume, but falls off rapidly as a new equilibrium is reached between intra and extravascular compartments. The rate of filtration is similar to that observed during localized congestion of the forearm.