PARTIAL URETERAL OBSTRUCTION - EFFECT OF INTRAVENOUS NORMAL SALINE AND FUROSEMIDE UPON THE RENAL RESISTIVE INDEX

Objective: To investigate the effect of intravenous normal saline flui d load, with and without furosemide, upon the renal resistive index (R I) of obstructed and nonobstructed kidneys. Methods: Right partial ure teral obstruction was induced in 10 dogs. Grade 1 (mild) obstruction w as performed in 5 dogs (group A), and grade 3 (severe) obstruction was carried out to the remaining 5 dogs (group B). Evaluation by Doppler ultrasonography was performed before induction of ureteral obstruction and by the end of the 8th week of obstruction. Every obstructed anima l was subjected to bilateral renal Doppler ultrasonography 3 times in one setting: 1) before infusion of normal saline, 2) 30-60 minutes aft er intravenous infusion of normal saline (15 ml./kg.) given in a rate of 1 ml./kg./min. and 3) 10 minutes after admission of furosemide (1 m g./kg.). Results: After induction of right partial ureteral obstructio n, there was a significant increase of the RI of the right kidney and a significant decrease of the RI of the left kidney compared to baseli ne RI in both groups. Infusion of normal saline and administration of furosemide caused a further significant increase of the RI of the obst ructed kidney and a further significant decrease of the RI in the nono bstructed kidney in both groups. Conclusion: In unilateral partial ure teral obstruction, addition of intravenous normal saline and furosemid e cause the RI to increase in obstructed kidney and to decrease in non obstructed kidney. Such a divergent response may be useful for the dev elopment of a pharmacologically challenged Doppler examination to diag nose better potentially obstructed kidneys.