EFFECTS OF ACUTE HEMORRHAGIC AND TRAUMATIC SHOCK ON RENAL FUNCTION OF DOGS

Abstract

Extraction of [rho]- aminohippuric acid from the plasma of blood perfusing the kidneys of dogs has been found to be 87% complete, with a . standard deviation of [plus or minus]4%. In estimating the extraction, a correction was found necessary for diffusion of [rho]-amino-hippuric acid from cells to plasma in the renal venous blood during the drawing and centrifugation of the blood; by use of rapid and uniform technique this correction could be kept down to 5 [plus or minus] 1%. Acute hemorrhagic or traumatic shock did not alter the percentage extracted, unless shock was so severe that the renal blood flow was retarded to less than about 3% of normal. Except in this extreme condition, the renal plasma flow could be calculated as the plasma [rho]-amino-hippuric acid clearance/0.87, with an error within the range [plus or minus]9%, and usually less than 5%. After sudden hemorrhage of 20-30 ml/kg the sequence of events observed in dogs under nembutal anesthesia was a drop in arterial blood pressure to 50-60 mm., with cessation of measurable renal blood flow and excretion, followed quickly by partial or nearly complete restoration of central blood pressure and of renal function. The restoration appeared to be attributable to constriction of the extra-renal peripheral vessels, and to indicate that renal circulation was favored at the expense of extra-renal peripheral circulation. However, if further progressive hemorrhage followed, over the approximate range, 30-40 cc./kg, this blood loss was accompanied by decrease in renal blood flow, although central blood pressure might be maintained above 110 mm. During this period the fraction of plasma water filtered in the glomeruli, as measured by the creatinine extraction, tended to increase, and thereby to uphold the vol. flow of glomerular filtrate despite the shrinkage in renal blood flow. The circulatory phenomena during this period apparently included partial constriction of the afferent renal vessels, adding renal to peripheral constriction in the endeavor to maintain central blood pressure, while the efferent renal vessels constricted still more than the afferent, to produce the compensatory increase in the fraction of plasma water filtered. When hemorrhage surpassed a certain limit, about 40-45 ml/kg, or when blood lost by somewhat smaller hemorrhage was not replaced for some hrs., or when muscle trauma exceeded a certain limit, both renal blood flow and the fraction of plasma water filtered fell to almost zero levels. This renal debacle might occur when the central blood pressure was still 80-100 mm. It appeared that by maximum afferent renal constriction the organism at this stage temporarily strangled renal function in an effort to maintain central blood pressure. If not too severe or prolonged, the condition in this stage was still reversible by infusion of blood or plasma, or by spon-taneous recovery. The relations between central blood pressure, renal blood flow, and glomerular filtration in shock caused by muscle trauma were similar to the relations noted in shock caused by hemorrhage.