Changes in Central Venous Pressure after Moderate Hemorrhage and

Changes in central venous pressure were recorded continuously before, during and for 40 to 50 minutes after hemorrhage and transfusion in the amounts of 6.5 cc. per Kg. and 8.1 cc. per Kg. The pressures obtained 15 to 20 minutes after onset of blood volume changes were independent of the rate of hemorrhage or transfusion. In the average subject of 70 Kg., AP/AV for zero time was 0.7 cm. of water pressure change per 100 cc. volume change. Recovery from hemorrhage was im-perceptible during the one hour observation period, but recovery from transfusion was slightly faster. WITH moderate hemorrhage or trans-fusion, it has been, shown in animalsthat the pressures at all locations from the great veins to the left atrium change in unison and by approximately the same amount.1 Human studies also suggest that these volume-conditioned pressure changes are of approximately the same magnitude through-out the low-pressure system2 and that the changes may persist for a period of time. ' The general opinion, however, as recently reviewed by Landis and Hortenstine,4 maintains that the venous pressure is regulated in much the same way as arterial pressure; with hemorrhage, for example, peripheral vasoconstriction, particu-larly venoconstriction, quickly restores the cen-tral venous pressure. It is the purpose of this paper to investigate the degree of central ve-nous pressure change associated with relatively small alterations in total blood volume and to determine the length of time the pressure changes persist. METHOD In 12 male subjects, 25 to 44 years of age, changes of central venous pressure were recorded continu-ously during and for 40 to 50 minutes following hemorrhage or infusion of 400 to 600 cc. of blood. The change in central venous pressure was recorde