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Objective To study the effect of hyperhydration with normal saline and frusemide on the renal resistive index (RI) in children with equivocal obstructive uropathy. Patients and methods Twelve children (24 kidneys) with unilateral or bilateral hydronephrosis underwent isotopic diuretic renography and Doppler ultrasonography. All children had equivocal obstruction of the hydronephrotic kidneys with half-time drainage (T/2) values of 10-20 min. Doppler studies were carried out both at baseline and after the infusion of normal saline and frusemide. Results Of the 24 kidneys, five were normal and 19 were hydronephrotic; compared with normal kidneys, the hydronephrotic units had a significantly lower glomerular filtration rate (GFR) and longer T/2. At baseline, the mean RI values of normal and hydronephrotic kidneys were not significantly different (0.70, sd 0.03 and 0.71, sd 0.04, respectively). After the infusion of saline and frusemide, the mean RI of hydronephrotic kidneys (0.67, sd 0.07) was significantly ( P=0.01) higher than that of normal kidneys (0.60, sd 0.02), but the response of RI in hydronephrotic kidneys was variable. Based on the RI at baseline and after infusion, hydronephrotic kidneys could be categorized into three groups. Group 1 ( n=6) had an RI<0.7 before and after infusion, group 2 ( n=6) had a baseline RI>0.7 and <0.7 after infusion, and in group 3 ( n=7) both RIs were >0.7. Kidneys in group 3 had the lowest GFR and the highest T/2 values. Five of these seven hydronephrotic kidneys eventually had deteriorating GFRs requiring surgical correction; the GFR of the remaining hydronephrotic kidneys remained stable. Conclusion In children with equivocal obstructive uropathy based on diuretic renography, the determination of RI before and after infusion of normal saline and frusemide could be helpful in distinguishing obstructed from non-obstructed kidneys. [ABSTRACT FROM AUTHOR] more...

Objectives To study the changes in renal resistive index (RI) and renal function with time during different grades of partial unilateral ureteric obstruction, and to determine the correlation between the ultrasonographic and renographic findings. Materials and methods Ten dogs underwent right partial ureteric obstruction; grade 1 (mild) obstruction was applied in five dogs (group A) and grade 3 (moderate and severe) obstruction in the other five (group B). All dogs were assessed using excretory urography, diuretic renography with the calculation of half-time drainage (Tn) and bilateral renal Doppler ultrasonography before the experiment began, after one week of obstruction, and every 2 weeks during 8 weeks of obstruction. Results In both groups, after the induction of right ureteric obstruction, there was a progressive decrease of effective renal plasma flow (ERPF) and a progressive increase of the RI of the right kidney at the end of the first and second weeks of obstruction, with an almost stable value thereafter. The decrease of ERPF and the increase of RI in the right kidney were correlated with the degree of obstruction. There was also a dramatic increase of Tn of the right kidney that correlated with the degree of obstruction. Concomitantly, there was a significant compensatory increase of ERPF and a significant decrease of the RI of the left kidney in both groups. The compensatory increase in ERPF limited the loss in total ERPF in both groups. The contribution of obstructed kidney to the total ERPF was significantly reduced in both groups. At the end of the eighth week, taking all kidneys together, there was a statistically significant negative correlation between the ERPF and RI, and between ERPF and Tn, and a positive correlation between Tn and RI. Conclusions Unilateral partial ureteric obstruction increased the RI and Tn and decreased the ERPF of the corresponding kidney, together with a decrease of RI and an increase in ERPF of the contralateral kidney. The more severe the obstruction, the greater the increase in RI and Tn and the decrease in ERPF. After the obstruction stabilized, RI and T n were positively correlated. [ABSTRACT FROM AUTHOR] more...