Renal circulation in man studied by means of a dye-dilution method

A dye-dilution method of measuring renal hemodynamics in man has been described. The method requires catheterization of both the renal artery and the renal vein, a single injection of dye into the renal artery, and recording of the venous dilution curve by means of a cuvette densitometer. The method was evaluated in 11 normal subjects, eight patients with acute anuric renal failure, and 13 patients with chronic renal disease. In 26 instances the PAH clearance and the PAH-extraction ratio were determined simultaneously. The dye-PAH flow ratio averaged 0.98 for the whole series. The limitations of the dye method have been discussed. The dye method probably makes it possible to estimate the blood flow distribution within the human kidney. The available data indicate that cortical blood flow in the normal kidney ranges from 80 to 93% of the total flow, with a mean transit time of 5 to 10 sec. The calculated cortical vascular volume ranges from 52 to 78% of the total volume. The extracortical flow presumably represents medullary circulation with a mean transit time of 19 to 25 sec. In anuric renal failure the total renal blood flow averaged 55% of normal and did not increase significantly during the subsequent polyuria. The shape of the dilution curves remained essentially normal in anuria and polyuria as well.