Dye Dilution Measurement of Renal Blood Flow in Vivo and in Glass Models

The dye dilution method in measurements of the renal blood flow was investigated in 18 patients, and by streamline studies and model experiments in glass models of the aorta and the renal arteries.A turbulent flow in the renal artery was observed only in stenosis of the artery. The flow disturbance in the renal artery was influenced by the angle between the renal artery and the aorta; at an angle of 45° between the infra-renal aorta and the renal artery it was not possible to obtain reproducible dye dilution curves from the renal artery in model experiments. The flow disturbance necessary for adequate mixing of dye and blood in the renal artery seemed to be provoked by the injection of dye into the arterial lumen in model experiments; flushing of the dye into the renal artery prevented transient retention of dye in the renal artery in the glass models.In four out of sixteen patients with single renal arteries and in two patients with double arteries reproducible dye dilution curves were not obtained. In the others the analysis error in measurements of the renal blood flow was 4.0% and not significantly different from the corresponding error in measurements of the systemic blood flow, 3.7%.