CARDIOVASCULAR EFFECTS OF LARGE VOLUMES OF ISOTONIC SALINE INFUSED INTRAVENOUSLY INTO DOGS FOLLOWING SEVERE HEMORRHAGE

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Abstract
A study has been made of the effects of hemorrhage and of an intraven. infusion of a large volume of isotonic salt soln. on the circulatory system. Calculated residual blood volumes average 61 cc./kg. 1 hr. after hemorrhage. Nevertheless, 23 of the 27 dogs survived. In 6 control expts. 5 dogs died within 2-5 hrs. after the hemorrhage. The avg. hematocrit reading was decreased by the saline infusion. 18 hours later it had not varied significantly from this post-infusion level. Avg. values for plasma protein concn. showed a similar decreased following the saline infusion but had increased significantly the following day. Calculation of the total circulating plasm protein showed that after hemorrhage an avg. of 0.9 g./kg. of body wt. had been added to the blood. After infusion the plasma volume averaged 8 cc./kg. above the control, but the total blood volume was 15 cc./kg. below the control. The dogs drank copiously and excreted large volumes of urine. Oxygen consumption showed an avg. reduction of 27% following hemorrhage but after the infusion it was only 10% less than the control values. By the next day the avg. O2 consumption was the same as the control rate. The avg. control cardiac output of 274 [plus or minus] 54 cc./min./kg. was reduced to 1/4 immediately following hemorrhage. The saline inflow brought it up to 265 [plus or minus] 58 cc./min.Ag-, and the following day it was 274 + 65, the same as the control output. In accord with the hematocrit changes, the avg. arterial O2 content fell after the infusion from 16.4 to 9.2 vol.%, being slightly increased on the 2d day. The venous O2 content, though lowered from 13.7 to 4 vol. % by the bleeding, rose after the infusion to 5.2 vol. % and remained in that range. Thus, the avg. A-V O2 difference increased from a control of 4.3 vol.% to one of 12 vol.% after hemorrhage. The infusion restored it to 4 vol.% and it was not significantly changed 24 hrs. later. These circulatory changes induced by the large saline infusion offer an explanation of the beneficial effects observed.