THE VALUE OF DOPPLER RESISTIVE INDEX AND PEAK SYSTOLIC VELOCITY IN THE EVALUATION OF PORCINE RENAL OBSTRUCTION

Purpose: We evaluated the use of Doppler resistive indexes and systoli c velocities as diagnostic tools in a partially obstructed animal mode l. Materials and Methods: We studied 12 normal pigs by Doppler sonogra phy, which served as control units. In 9 subjects partial ureteral obs truction was then created surgically, and 3 continued as controls. The presence or absence of obstruction was confirmed by ultrasound, anteg rade nephrostography and intrapelvic pressure monitoring. Doppler para meters were measured 1 hour to 21 days postoperatively. Resistive inde x, and angle corrected peak and mean systolic velocities were measured bilaterally from samplings of interlobar and arcuate arteries. An ave rage of 4 samplings per kidney was obtained at each session. Data from the control and obstruction groups were compared for statistical diff erences. Results: In controls mean resistive index was 0.53, and peak and mean systolic velocities were 0.38 and 0.26 m, per second, respect ively. In the subacute period after obstruction (defined as days 4 to 21) mean resistive index was 0.54, and peak and mean systolic velociti es were 0.33 and 0.22 m, per second, respectively. Compared to control data there was no significant change in resistive index after obstruc tion (p = 0.6). However, peak and mean systolic velocities showed sign ificant downward trends (p <0.05). Conclusions: Known small sequential changes in renal blood flow after ureteral obstruction are reflected in flow velocities, as measured by duplex Doppler sonography. However, resistive indexes are not useful in assessing these changes in renal blood flow, and they do not correlate with the presence or absence of obstruction in this animal model.