Renal hemodynamics in patients with obstructive uropathy evaluated by color Doppler sonography

Prior animal studies have shown through direct pressure measurements that there is a definite rise in the renal vascular resistance in obstruction. Therefore intrarenal hemodynamic changes can be determined by the vascular impedance expressed as pulsatility and resistive indexes (PI and RI) obtained from the Doppler waveforms of intrarenal arteries. We investigated whether various degrees of obstruction result in different hemodynamic responses according to color Doppler sonography.

22 kidneys with varied degrees of hydronephrosis and 19 normal kidneys were examined. The pulsatility and resistive index of Doppler waveforms from interlobar arteries were obtained. The grade of hydronephrosis was based upon the width of parenchyma.

The mean resistive index in the study and controls were 0.70 +/- 0.07 and 0.60 +/- 0.03, respectively. The difference was significant (p < 0.001). Pulsatility indexes in the study and controls were 1.07 +/- 0.34 and 0.98 +/- 0.23, respectively. The difference was not significant (p > 0.005). Significant difference was also noticed in the parenchymal widths between both groups (p < 0.001).

It appeared that intrarenal color Doppler sonography can provide physiologic information reflecting renal vascular resistance status by means of an easily obtained parameter: resistive index.