Renal arterial duplex Doppler ultrasound in dogs with urinary obstruction

Recent clinical studies using duplex Doppler sonography identified an alteration in renal arterial blood flow in obstructed hydronephrotic kidneys that reportedly can be used to distinguish obstructive from nonobstructive collecting system dilatation. We attempted to verify these clinical findings and establish the temporal relationship of the alteration in the Doppler spectrum to the onset of urinary obstruction by evaluating surgically induced urinary obstruction in dogs. We performed laparotomies on 11 dogs, with the left ureter isolated and ligated in five dogs, and left intact in six dogs (control group). Duplex Doppler examination of the left renal arteries performed nine times during the first postoperative month identified a statistically significant difference (p less than .05) in the Doppler resistive index calculation between the two groups on days 1, 2, 4, and week 4. A resistive index discriminatory threshold of 0.7 (greater than 0.7, obstructed; less than 0.7, nonobstructed) produced a test sensitivity of 74% and specificity of 77%. We conclude from our study that renal arterial duplex Doppler sonography can detect a change in renal perfusion as a result of urinary obstruction and that this change can be detected as early as 24 hours after obstruction. However, high false-positive and false-negative rates may limit the ability of this modality to reliably distinguish obstructive from nonobstructive collecting system dilatation.     

Clinical Value of Renovascular Resistive Index Measurement in the Diagnosis of Acute Obstructive Uropathy

Purpose

We evaluated the clinical use of the renal resistive index in identifying patients with acute urinary tract obstruction.

Materials and Methods

Of 54 patients with suspected acute urinary tract obstruction who underwent measurements of renal resistive index 19 had unilateral obstruction documented with excretory urography and comprise our study sample. The contralateral nonobstructed kidneys served as controls. Criteria for obstruction were a resistive index of 0.70 or greater or a side to side difference of 0.10 or greater. We calculated sensitivity, specificity, and positive and negative predictive values.

Results

Sensitivity for obstruction was 42% with 11 false-positive cases, specificity was 79%, and positive and negative predictive values were 67 and 57%, respectively.

Conclusions

Renal resistive index measurements are not valuable in detecting acute urinary tract obstruction.     

Diabetes mellitus worsens intrarenal hemodynamic abnormalities in nondialyzed patients with chronic renal failure

Duplex Doppler sonography has been reported to be useful in examining the intrarenal hemodynamic abnormalities in various renal diseases. We investigated the impact of diabetes on intrarenal hemodynamics in patients with chronic renal failure (CRF). The resistive index and pulsatility index of the renal interlobar arteries were measured using duplex Doppler sonography in 90 CRF patients (serum creatinine >130 and <800 mmol/l, mean age 59 +/- 11 years). Forty-eight patients had type 2 diabetes and 42 did not. Twenty-nine age-matched, healthy subjects served as controls. Both resistive index and pulsatility index were greater in CRF patients than in the controls (p < 0.0001). No significant differences existed in age, sex, body mass index, total serum cholesterol, serum creatinine, estimated creatinine clearance, or mean blood pressure between the diabetic CRF and nondiabetic CRF groups. Resistive index and pulsatility index were significantly increased in the diabetic CRF patients compared to the nondiabetic CRF patients (p < 0.0001). Multiple regression analysis of all CRF patients revealed that resistive index was independently affected by the presence of type 2 diabetes (F = 44.535), as well as decreased creatinine clearance (F = 18.157) and age (F = 15.160) (R(2) = 0.559, p < 0.0001). These results clearly demonstrated that intrarenal arterial resistance is significantly increased in CRF patients with type 2 diabetes compared to similar patients without diabetes. The impact of diabetes mellitus and advanced age on intrarenal hemodynamics may be due to intrarenal arteriosclerosis and interstitital lesions. Measurements of RI values in addition to conventional ultrasound imaging may add further information on such renal lesions.     

Doppler resistive index in benign prostatic hyperplasia: correlation with ultrasonic appearance of the prostate and infravesical obstruction

OBJECTIVE: This study was designed to characterize the resistive index (RI) of prostatic blood flows obtained by transrectal power Doppler sonography (TRPDS) in benign prostatic hyperplasia (BPH). METHOD: In 140 patients with lower urinary tract symptoms, the RI was measured using TRPDS and compared with age and planimetric parameters of the prostate obtained by conventional transrectal sonography. In addition, the RI was related with pressure flow studies. RESULTS: The RI was significantly higher in patients with BPH (0.72+/-0.06, p<0.0001) than those with a normal prostate (0. 64+/-0.04). Although the RI correlated significantly with age and all prostatic planimetric parameters, multiple regression analysis revealed that age and presumed circle area ratio were independent predictors for RI. The RI was also higher in patients with infravesical obstruction than those without (0.74+/-0.06 vs. 0. 70+/-0.05, p<0.005). There was a significant correlation between RI and urodynamic parameters obtained in pressure flow studies. Out of 33 patients with obstruction, 28 (85%) had an RI of 0.7 or more, while 11 out of 24 patients (46%) without obstruction had an RI less than 0.7. CONCLUSION: The RI is promising as a new parameter to estimate the intraprostatic pressure to investigate BPH. Its value to represent urodynamic information during voiding remains to be studied.     

Evaluation of renal transplant dysfunction by duplex Doppler sonography: a prospective study and review of the literature

A disconcertingly wide variation exists in the literature as to the accuracy of duplex Doppler sonography in the detection of acute renal transplant rejection. Sensitivities range from 9% to 76%. In an attempt to explain the disparity of results, we undertook a double-blind prospective study of the accuracy of duplex Doppler ultrasound in the detection of acute rejection in renal transplants. We scanned 49 consecutive patients with a total of 65 biopsies; 46 biopsies in 33 consecutive patients were included in our study. In our population, the prevalence of acute rejection was 61% (28/46). Using a resistive index (RI) cutoff of greater than 0.90 based on the main renal artery flow pattern, the sensitivity of our test was 43%, with a 67% specificity. The positive predictive value was 67%. Our results are contrasted and compared with the published data from other groups in a critical survey of the literature. We conclude that duplex Doppler sonography alone is inadequate to evaluate acute rejection in renal transplants.     

Prospective comparison of nonenhanced helical computerized tomography and Doppler ultrasonography for the diagnosis of renal colic

PURPOSE: We evaluate the accuracy of nonenhanced helical computerized tomography (CT) and Doppler ultrasonography for the diagnosis of renal colic. MATERIALS AND METHODS: Our study includes 109 patients, with 218 kidneys, who presented with unilateral flank pain. All patients underwent nonenhanced helical CT, Doppler ultrasonography and excretory urography (IVP). CT was evaluated for the presence of ureteral stones and manifestation of ureteral obstruction. For Doppler ultrasonography the renal resistive index was measured for the left and right kidneys in each patient, and change in resistive index between ipsilateral and contralateral kidneys was calculated and considered positive for ureteral obstruction with values 0.04 or greater. As a reference standard, absence of obstruction was considered if IVP was negative and the cause of flank pain was confirmed not to be urological. Obstruction was diagnosed not only by positive IVP, but also by patient followup until passage or retrieval of ureteral stones. Results of CT and change in resistive index were compared with those of the reference standard. RESULTS: Unilateral ureteral obstruction was confirmed in 52 patients, while no obstruction was found in 57. Of the 57 patients without ureterolithiasis the change in resistive index results was negative in all patients with a specificity of 100%, while CT was negative in 55 with a specificity of 96%. Of the 52 patients with ureteral obstruction CT was positive in 50, and change in resistive index was positive in 47 with a sensitivity of 96% and 90%, respectively, with a difference of no significant value. CONCLUSIONS: Nonenhanced helical CT and change in resistive index are sensitive and specific tests that can contribute significantly to the diagnosis of acute unilateral renal obstruction. They can replace IVP, particularly in situations in which it is undesirable.     

Alterations of mesenteric blood flow after cardiopulmonary bypass: a Doppler sonographic study

OBJECTIVE: Mesenteric ischemia after cardiopulmonary bypass is a serious complication associated with high mortality. It was the aim of this study to investigate mesenteric blood flow with the help of Doppler sonography in asymptomatic patients before and after cardiopulmonary bypass and cardiac surgery. DESIGN: Observational study of consecutive patients. SETTING: Nonuniversity cardiac center. PARTICIPANTS: Twenty-five patients undergoing elective coronary revascularization with normal left ventricular function and stable postoperative circulations with no need for catecholamines. MEASUREMENTS AND MAIN RESULTS: Preoperative and postoperative color and CW-Doppler sonography of the superior mesenteric artery. Diameter of the superior mesenteric artery and the Doppler flow profile were analyzed. Preoperative and postoperative hemodynamic data were measured by using a pulmonary artery thermodilution catheter. Mesenteric systolic flow velocity was 135 +/- 11 cm/s preoperatively and 193 +/- 13 cm/s postoperatively (p < 0.05). The corresponding preoperative and postoperative values of diastolic flow velocity were 14 +/- 4 and 4 +/- 2 cm/s (p < 0.05) and the values of mean flow velocity were 24 +/- 3 and 17 +/- 2 cm/s (p < 0.05), respectively. The preoperative Pourcelot resistive index was 0.87 +/- 0.05, and the preoperative Gosling pulsatility index was 4.6 +/- 0.5. Both indices increased postoperatively to values of 0.98 +/- 0.04 and 9.5 +/- 0.7, respectively (p < 0.05). Preoperative and postoperative hemodynamic data did not differ significantly. CONCLUSION: The postoperative changes in the flow velocities and the increases of the resistive and pulsatility index are indications of rigidity of the mesenteric vascular bed and decreased mesenteric perfusion after cardiopulmonary bypass.     

Assessment of obstruction in adult ureterocele by means of color Doppler duplex sonography

AIM: The purpose of this study is to present a method for identifying a ureteral obstruction in unilateral orthotopic ureterocele by means of conventional sonography and color Doppler duplex sonography. We focus on the measurement of the ureterocele dimensions, the degree of dilation it causes to the ipsilateral upper urinary tract, the registration of urine out-flow from the ureteral orifice into the bladder and its spectral analysis. MATERIAL AND METHOD: Over 2 years at our institutions, 8 adult patients (7 women, 1 man) were diagnosed as having a single system orthotopic ureterocele. Four of them presented with lumbar pain, dysuria and recurrent urinary tract infections, while the remainder were asymptomatic and diagnosed accidentally. The diagnosis was based on serial sonography of the upper and lower urinary tract confirmed by intravenous pyelography and cystoscopy. We also performed color Doppler duplex sonographic evaluation of the urine jets ejected from both ureteral orifices into the bladder. Using the flow spectral study we analyzed the waveforms and measured their duration and flow rate. The study was completed with a comparative analysis of the data obtained from both ureteral orifices. RESULTS: Cystic dilation of the lower ureteric extremity into the bladder was presented in all cases. Upper urinary tract dilation, of various grades, was present in 4 of 8 patients. Differences in urine jets between those derived from the ureterocele and those from the healthy contralateral ureteral orifice were significant in those patients with dilation of the upper urinary tract. The differences concerned mainly the frequency and symmetry of the jets as well as the pattern, duration and velocity of their waves. The 4 above-mentioned patients, with dilated upper urinary tracts and waveforms differentiated from the contralateral ones, were characterized as obstructive. On the other hand, the remaining 4 patients with subclinical ureterocele showed insignificant differences in urine jets and waveforms, and were found to be non-obstructive. CONCLUSION: Conventional sonography of the urinary tract in combination with color Doppler duplex sonography of the ureteral jets can be used in an attempt to diagnose and evaluate a unilateral orthotopic (single system) ureterocele and assess the necessity of intervention to identify the obstruction.     

The place of diuretic enhanced Doppler sonography in distinguishing between obstructive and non-obstructive hydronephrosis in children

OBJECTIVE: In an attempt to differentiate obstructive from non-obstructive dilation of the renal collecting system in children, a prospective clinical study was carried out. MATERIAL AND METHODS: During duplex Doppler sonography examination in 23 children resistive index (RI) and pulsatility index (PI) and RI ratio values before and after intraverous furasemide administration were compared with the findings obtained with diuretic renogram examination (t(1/2)). RESULTS: Evaluation of the results demonstrated that diuresis RI and PI determination may aid differentiation of severely obstructed renal units from those with slight (equivocal) or no obstruction. CONCLUSION: Kidneys with severe UPJ obstruction tended to have more elevated RI and PI values than the non-obstructed or equivocally obstructed ones. Again, determination of RIR values for each kidney showed the same elevation in severely obstructed kidneys, while non-obstructive or indeterminately obstructed ones demonstrated statistically insignificant changes.     

High resistive index of the radial artery is related to early primary radiocephalic hemodialysis fistula failure

Forty-nine patients who had received radiocephalic hemodialysis fistula construction were evaluated with duplex Doppler ultrasonography to characterize the Doppler indices of the feed radial arteries just proximal to the site of anastomosis. Forty-four patients had fistulas with good function, and 5 patients had fistulas with inadequate blood flow or thrombosis within 4 weeks after the operation. A preliminary study showed extensive variability in peak systolic velocity and end-diastolic velocity in the feed arteries. The resistive index dropped significantly 1 week after the operation and remained relatively constant over the following 5 weeks. In the success group, the mean resistive index measured 1 week after operation was 0.40+/-0.06. It was higher than that of the failure group (mean resistive index: 0.52+/-0.06). Among patients with well-functioning fistulas, diabetic patients had higher resistive indices than did non-diabetic patients (0.44+/-0.04 vs. 0.37+/-0.06). Our results suggest that a higher resistive index of the feed artery is closely related to early autogenous primary hemodialysis fistula failure.     

Role of resistive index in renal colic

We studied the role of duplex Doppler ultrasonography in the diagnosis of renal obstruction caused by ureteral calculi. Using duplex Doppler sonography, we evaluated the intrarenal hemodynamics of 27 patients who presented to the emergency department with renal colic. We performed Doppler ultrasonography on patients in whom US did not reveal any pathology causing renal colic and calculated and compared mean RI values of normal and obstructed kidneys and ΔRI values of each group. Threshold levels for the diagnosis of urinary tract obstruction (mean RI ≥ 0.70 and ΔRI ≥ 0.08) were used to determine the sensitivity and specificity of Doppler sonography for the diagnosis of urinary tract obstruction. Patients were investigated for revealing calculi diagnosis either by stone excretion history, intravenous pyelography or non contrast enhanced urinary computed tomography. A total of 162 intrarenal arterial Doppler recordings were made on 54 kidneys. Of the 16 patients with urinary obstruction, 11 (68%) had sonographic evidence of pelvicalyceal dilatation. The mean RI of the 16 obstructed and 11 unobstructed kidneys was 0.69 ± 0.04 and 0.61 ± 0.06 (mean ± standard deviation), respectively. The difference between the mean RI values for each group was statistically significant (P < 0.05). Mean RI values of the contralateral kidneys in the obstructed group and unobstructed group were 0.61 ± 0.03 and 0.59 ± 0.05, respectively. Also ΔRI value (0.07 ± 0.02) of obstructed kidney group was statistically higher than the ΔRI value (0.01 ± 0.03) of the unobstructed group (P < 0.05). The mean RI of the 16 obstructed kidneys (0.69 ± 0.04) was significantly greater than that of the 16 unobstructed contralateral kidneys (0.61 ± 0.03) (P < 0.05). This study supplements the existing evidence that, in acutely obstructed kidneys, renal Doppler recording can demonstrate altered renal perfusion before pelvicalyceal system dilatation and distinguish obstructed and unobstructed kidneys evaluated with suspicion of renal colic.     

Dilated renal collecting systems: differentiating obstructive from nonobstructive dilation using duplex Doppler ultrasound

Two patients with ileal loop urinary diversions, studied with real-time and Doppler sonography ("duplex sonography") of the kidneys, were shown to have dilated intrarenal collecting systems. Resistive index measurements calculated from the Doppler signal correctly identified obstructive dilatation in 1 case and nonobstructive dilatation in the other.     

Captopril renography and duplex Doppler sonography in the diagnosis of renovascular hypertension

Background. The purpose of this prospective study was to determine the clinical usefulness of captopril renal scintigraphy and duplex Doppler sonography in detecting haemodynamically significant renal artery stenosis (⩾60%) and predicting cure or improvement of hypertension following revascularisation. Methods. Twenty-eight patients with moderate or high index of clinical suspicion of renovascular hypertension underwent both captopril renal scintigraphy and duplex Doppler sonography before undergoing renal angiography. Patients with angiographically proved (⩾60%) RAS were treated by percutaneous transluminal renal angioplasty unless it was contraindicated. Results. The results of captopril renal scintigraphy and duplex Doppler sonography were compared by renal angiography of 45 renal arteries in 28 patients. Eleven renal arteries were excluded from further comparison, because no accurate Doppler signal could be obtained. The sensitivity and specificity of captopril renal scintigraphy in the identification of RAS (⩾60%) was 78% and 81% respectively. The sensitivity of duplex Doppler sonography was 83% and the specificity was 81%. Positive predictive values of both tests for blood pressure cure or improvement after PTRA were 86% for CRS and 85% for DDS. Conclusions. Captopril renal scintigraphy and duplex Doppler sonography are comparable tests for detection of patients with haemodynamically significant renal artery stenosis (⩾60%). Positive predictive values of both tests for cure or improvement of hypertension after percutaneous transluminal renal angioplasty are good and comparable.     

Comparison of selective internal iliac pharmaco-angiography, penile brachial index and duplex sonography with pulsed Doppler analysis for the evaluation of vasculogenic (arteriogenic) impotence

Between July 1987 and February 1988 selective internal iliac angiography was performed before and after intracavernous injection of papaverine plus phentolamine in 43 patients with erectile dysfunction. In 63% of the patients stenosis or occlusion of the pudendal artery was found. The penile brachial index was calculated and duplex sonography with pulsed Doppler analysis was performed in 23 patients. Angiography and penile brachial index correlated in only 39% of the patients, whereas selective internal iliac angiography and duplex sonography correlated in 91% (21 of 23). In 2 patients duplex sonography with pulsed Doppler analysis rendered better information about penile arterial perfusion than did angiography.     

Resistive index in renal colic: a prospective study

OBJECTIVE: To study the role of Doppler ultrasonography (DU) in the diagnosis of acute unilateral renal obstruction. PATIENTS AND METHODS: In all, 117 patients with suspected renal colic were evaluated by intravenous urography (IVU) and DU, with determination of the resistive index (RI) and the difference between the RI of ipsilateral and contralateral kidneys (deltaRI). RI and deltaRI were considered positive with values of > or = 0.70 and > or = 0.06, respectively. IVU results were considered the 'gold standard' with which renal DU findings were compared. RESULTS: IVU showed both kidneys to be normal in 49 patients and unilateral ureteric obstruction with a normal contralateral kidney in 68. The mean (SD) RI was 0.73 (0.05) in 68 obstructed kidneys, significantly higher than the mean RI of 0.64 (0.05) in 166 normal kidneys (P<0.001). The deltaRI in patients with unilateral obstruction was significantly higher than that in patients with both kidneys normal, at 0.09 (0.05) and -0.001 (0.02), respectively (P<0.001). For all the patients, RI was sensitive in 77% and specific in 83%, and deltaRI was sensitive in 88% and specific in 98%. Obstructed kidneys showing delayed pelvicalyceal filling with excretion of contrast medium (n=42) had significantly higher values of RI and deltaRI than obstructed kidneys without delayed filling (n=26). The RI and deltaRI were more sensitive in the former group. Among patients with obstruction, the RI did not relate to the time of delay of filling with contrast medium, the duration of renal colic or the level of ureteric obstruction. CONCLUSIONS: Renal DU is a sensitive and highly specific test that can contribute significantly to the diagnosis of acute unilateral renal obstruction. It can replace the IVU, particularly in situations where IVU is undesirable.     

Role of duplex Doppler sonography in diagnosis of acute allograft dysfunction—time to stop measuring the resistive index?

Measurement of vascular resistive index (RI) by duplex Doppler sonography (DDS) has been proposed as a non-invasive technique to detect the presence of acute rejection in renal allograft recipients. Our aim was to evaluate the clinical utility of this technique. From 107 patients we reviewed 159 biopsies that were performed from 1993 to 2001 for the investigation of acute allograft dysfunction. Histological findings were correlated with RI measurements by contemporaneously performed DDS. The majority of biopsies were carried out within the first 3 months post-transplantation (111/159). Sixty-eight biopsies showed acute rejection, 91 biopsies had findings other than rejection (acute tubular necrosis, CyA toxicity, recurrent GN). Using a threshold mean RI value of 0.9, the test had a specificity for acute rejection of 89%, but a sensitivity of just 6%. If the threshold was lowered the sensitivity rose, but specificity declined sharply. Average RI in the rejection group was not higher than in controls (0.73+/-0.11 vs 0.74+/-0.11, respectively). We conclude that measurement of RI by DDS does not contribute to the diagnosis of acute allograft dysfunction.     

Doppler ultrasonographic indices after renal transplantation as renal function predictors

OBJECTIVES: Doppler ultrasonography is mostly used for assessment of both graft and native kidney vascular status. In this study, correlation between Doppler sonographic indices and transplanted kidney function was evaluated. METHODS: In our retrospective study, we reviewed data on 273 renal transplanted (RTx) patients. The Doppler ultrasonographic evaluation included resistive index (RI), pulsatility index (PI) in interlobar arteries as well as stenosis (TRAS) or thrombosis of renal arteries and veins. Serum creatinine (Cr) and cyclosporine levels (CsA) were measured just prior to sonography. RESULTS: The mean age of 154 male and 119 female patients was 36.67 +/- 13.13 years. Both RI and PI showed significant linear correlations with serum Cr (P = .033 and P = .002, respectively). Also, direct linear correlations existed between patient age and RI and PI values (P = .004; r = +.174 and P = .003; r = +.183 respectively). The prevalence of TRAS was 11.35%. Among patients with TRAS or thrombosis the mean Cr level (2.08 +/- 1.7 mg/dL) was significantly higher than that among patients without TRAS or thrombosis (1.48 +/- 0.97 mg/dL; P = .004). Despite this finding, RI and PI were significantly lower among patients with TRAS or thrombosis than those with a patent renovascular tributary (0.59 +/- 0.15 vs 0.65 +/- 0.11; P = .029 vs 1.02 +/- 0.40 vs 1.18 +/- 0.46; P = .049). CONCLUSIONS: Both RI and PI were two valuable Doppler ultrasonographic markers to evaluate renal allograft function and related vascular complications.     

The relationship of penile rigidity and intracavernous vascular resistance in potent men during intracavernous pharmacological testing

PURPOSE: We studied the relationship of penile rigidity and intracavernous vascular resistance in potent men during intracavernous pharmacological testing. MATERIALS AND METHODS: Enrolled in our study were 19 potent men undergoing intracavernous pharmacological testing for various reasons. Hemodynamic changes in response to the intracavernous injection of 20 microg. prostaglandin E1 were assessed by color Doppler sonography with simultaneous RigiScan (Dacomed Corp., Minneapolis, Minnesota) monitoring of penile rigidity. The relationship of penile rigidity and intracavernous vascular resistance was determined by correlating hemodynamic data with recorded penile rigidity values. RESULTS: Maximal mean rigidity plus or minus standard deviation of the penile tip and base after intracavernous injection of prostaglandin E1 was 76.8% +/- 8.5% and 97.3% +/- 4.7%, respectively. Penile tip and base rigidity correlated positively with the resistive index (r = 0.69 and 0.75, p <0.0001) and negatively with end diastolic velocity (r = -0.62 and -0.70, respectively, p <0.0001). The formula, rigidity = -128 + 195 x resistive index, was derived to describe the linear regression of penile base rigidity and the resistive index. The formula, rigidity = 59.8 - 3.3 x end diastolic velocity, was derived to describe the linear regression of penile base rigidity and end diastolic velocity. CONCLUSIONS: Penile rigidity correlated strongly with intracavernous vascular resistance in potent men during intracavernous pharmacological testing. The resistive index and end diastolic velocity of the cavernous arteries may each be used to estimate penile rigidity quantitatively.     

Time-dependent changes of resistive index in acute renal obstruction during nonsteroidal drug administration

OBJECTIVE: To evaluate Doppler ultrasonography (DUS) and assess time-dependent changes of the renal resistive index (RI) in acute unilateral renal obstruction during treatment with nonsteroidal analgesic for the relief of renal colic. PATIENTS AND METHODS: In 31 patients with symptoms of renal colic, treated with ketoprofen, unilateral obstruction was confirmed by intravenous urography. The patients were divided into four groups according to the duration of their symptoms, i.e. < 23 h, 24-47 h, 48-72 h and > 72 h. In each patient, the RI was measured over the arcuate, segmental and renal arteries of both kidneys using DUS. The values obtained in the obstructed kidney were compared with those for the contralateral kidney. RESULTS: The mean (sd) RIs for all 31 patients were 0.71 (0.05) for the obstructed and 0.60 (0.05) for the contralateral kidney (P < 0.001), the mean difference (dRI) being 0.12 (0.07). In those with obstruction for < 23 h the mean RI of the obstructed kidney was 0.70 (0.05) and of the contralateral healthy one 0.62 (0.07). Values of RI were similar in the group with obstruction for 24-47 h and 48-71 h. In those with obstruction for > 72 h the mean RI of the obstructed kidney was 0.69 (0.07) and of the contralateral one 0.60 (0.04), with a dRI of 0.09 (P < 0.005). The RI was 87% sensitive and 90% specific for detecting renal obstruction. CONCLUSION: Although the patients were given ketoprofen, their mean RI for the obstructed kidney remained above the discriminatory threshold (> 0.70) during the first 71 h of obstruction. Only in those obstructed for > 72 h was the mean RI on the obstructed side slightly below the threshold, but the difference between the kidneys was significant. The measurement of RI is a reliable diagnostic method for detecting acute renal obstruction. With a longer duration of symptoms, the difference in RI between the kidneys becomes clinically more relevant.     

Duplex sonographic registration of age and diabetes-related loss of renal vasodilatory response to nitroglycerine.

BACKGROUND: Nitroglycerine effects dilatation of the vas afferens in the kidney by its active metabolite nitric oxide (NO). In diabetic nephropathy, NO appears to cause hyperfiltration and proteinuria. The aim of this study was to investigate the potential of duplex Doppler ultrasonography in recording changes in resistive indices following nitroglycerine and whether the extent of changes in diabetic nephropathy is reduced as a result of the arteriolar dilatation mediated by NO. METHODS: Fifty-three subjects made up three groups: group 1, 12 young healthy volunteers (5 male, 7 female, 28+/-6 years); group 2, 21 older healthy volunteers (7 male, 14 female, 62+/-8 years); group 3, 20 patients (13 male, 7 female, 56+/-18 years) with mild diabetic nephropathy. The resistive index (RI) was measured in the interlobar arteries before, and 1, 3 and 5 min after administration of 0.8 mg sublingual nitroglycerine. RESULTS: The initial RI of 0.592 decreased in group 1 by 10.8% (P<0. 01) after nitroglycerine, in group 2 the initial figure of 0.631 decreased by 5.9% (P<0.01), and in group 3 the initial figure of 0. 669 decreased by 3.4% (P<0.01). Initial RI values differed significantly between groups 1 and 3 (P<0.01) and groups 1 and 2 (P<0.01), as did values between all healthy volunteers (groups 1 and 2, n=33) and patients with nephropathy (P<0.005). The extent of DeltaRI differed significantly between groups 1 and 3 (P<0.01), 1 and 2 (P<0.02), and between all volunteers and group 3 (P<0.003). In groups 1 and 2 the initial RI was dependent on age (P<0.03), in group 3 on age and creatinine clearance (P<0.02 and P<0.05 respectively). DeltaRI correlated with age in the healthy subjects (P<0.01) and with duration of diabetes in diabetic nephropathy (P0. 03). CONCLUSIONS: Haemodynamic changes in renal perfusion caused by nitroglycerine can be detected using duplex ultrasonography. In healthy subjects, DeltaRI declines with increasing age. In diabetic nephropathy patients, the response to nitroglycerine is reduced. The increased initial RI in such patients suggests fixed arteriolar damage.