The Renal Vascular Response to Acutely Elevated Intrapelvic Pressure: Resistive Index Measurements in Experimental Urinary Obstruction

Abstract

Because RI more closely reflects changes in renal blood flow than pelvic pressure, it can accurately diagnose acute obstruction but only after several hours. Diagnostic accuracy in chronic obstruction may be influenced by these physiologic relationships.

The Evaluation of Renal Hemodynamics with Doppler Ultrasonography

“…In 11 mongrel dogs, the RI range was 0.54 to 0.75 (0.64 ± 0.05) (Dodd et al, 1991a). However, Ulrich et al (1995) reported a 95% CI of 0.46 -0.62 (0.54 ± 0.04) in six mongrel dogs. In a study of healthy Persian cats, main renal artery RI values for the right kidney were 0.52 ± 0.07 and 0.55 ± 0.07 for the left kidney, with an intrarenal RI value obtained from the interlobar arteries of 0.51± 0.07 (Carvalho & Chammas, 2011).…”

“…The lack of response might have been due to a marked decrease in absolute blood flow in chronic high-grade obstruction, decreased filtration pressure produced by a renal cortex functioning at a minimal level or elevated compliance in a capacious dilated collecting system (Ulrich et al, 1995).…”

“…The obstructed to normal kidney RI ratio can also be helpful. Ulrich et al (1995) cited a ration of 1.15 as a diagnostic criterion of acute obstruction. Keller et al (1989) showed that with the RI ratio of ≥1.11, the sensitivity for determining obstruction was 77%, while the specificity for excluding obstruction was 81%, in a study involving 48 patients with unilateral obstruction and 34 healthy controls.…”

Ultrasonographic Examination of Some Vessels in Dogs and the Characteristics of Blood Flow in These Vessels

“…An increased RI was recorded 24 hours following the acute unilateral obstruction in dogs, however, due to the high number of false positive and false negative cases the reliability of the RI examination was limited [16].…”

Managing severe loin pain in pregnancy

“…The normal kidney has an resistive index of <0.7 and there is an increase in the resistive index to a value of >0.7 seen in the obstructed kidney because of the reduction in diastolic velocity and reduced blood flow seen in association with obstruction 15 . The measurement of resistive index reaches diagnostic sensitivity within 3 -4 hours 15,16 . Another role of ultrasound is the assessment of ureteric jets to diagnose an obstructed system 17 , although this technique does require prior experience.…”