THE RENAL CIRCULATION IN SHOCK 1

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Abstract
Changes in the renal circulation resulting from circulatory failure have been investigated by means of clearance methods in 35 human cases. The filtration rate and effective plasma flow are reduced, roughly in proportion to the severity of the shock. The decrease is usually greater than can be accounted for on the basis of the reduced arterial pressure. The observed decrease in the renal fraction (ratio of renal blood flow to cardiac output) indicates that blood is shunted away from the kidneys during shock. The increase in renal vascular resistance (ratio of mean arterial blood pressure to renal blood flow) suggests that renal vasoconstriction is the mechanism responsible for this redistribution of the circulation. It is shown that acidosis is not the primary cause of renal ischemia in shock. The degree of oliguria provides a rough estimate of the reduction in filtration rate and renal blood flow. Anuria in shock indicates almost complete cessation of the renal circulation. Alcoholism complicating moderate or slight oligemia tends to result in a relative vasodilatation, as evidenced by a lower filtration fraction and larger blood flow than in non-alcoholics with similar blood pressure. During and after blood or plasma transfusion the filtration fraction increases, suggesting a relative constriction of the efferent arterioles. The filtration rate increases with rise in blood pressure, but the renal blood flow tends to remain low or fall to subnormal levels after a temporary increase, in spite of the restoration to normal of the blood pressure and cardiac output. There was no death attributable to renal failure in this series of patients. The results confirm the hypothesis that oliguria or anuria, and the loss or impairment of concentrating power of the kidneys in shock, are the result of decreased renal circulation.