THE EFFECTS ON THE CARDIOVASCULAR SYSTEM OF FLUIDS ADMINISTERED INTRAVENOUSLY IN MAN. II. THE DYNAMICS OF THE CIRCULATION 1

Abstract

When 500 to 1500 cc. of physiological saline, 5% glucose or 5% glucose in physiol. saline solns., were injected at rates of less than 20 cc. per min., very slight changes were observed in the cardiovascular functions studied; the blood vol. was usually considerably increased. When these vols. of fluid were injected at more rapid rates considerable increases in venous pressure, cardiac output, velocity of blood flow, and in blood vol. were usually observed; in-creases in pulse rate, pulse pressure, and in the P wave of the electrocardiogram occurred in some instances. The greater ven. pres. increases occurred in subjects who received fluids in the larger vols. and at the more rapid rates. The ven. pres. invariably returned to the control level within 10 to 25 min. after the end of fluid admin. Significant increases in cardiac output occurred in patients in whom the intraven. inj. of fluids resulted in rises in ven. pres. When fluids were injected in larger vol. and at more rapid rates the increase in velocity of blood flow was less than that expected from changes in the cardiac output. In some cases the increase in velocity of blood flow was greater after the inj. of 500 cc. of fluid than after 1000 to 1500 cc. Increase in pulmonary blood vol. apparently occurs during inj. Dyspnea did not occur, and changes in respiratory dynamics were not observed. The fact that rises in ven. pres. did not persist, or did not even occur, in spite of increased blood vol., together with the observation of increasing diffuse flush of the skin, point to a progressive peripheral vasodilatation during inj. of fluids. Additional evidence is the increased pulse pressure observed in some subjects.