No rise in renal Doppler resistance indices at peak serum levels of cyclosporin A in stable kidney transplant patients.

BACKGROUND: The measurement of intrarenal resistance indices by duplex ultrasound plays an important role in the follow-up care of renal transplant patients. Increasing resistance indices indicate rejection episodes, but may also occur e.g. in parenchymal renal diseases. As calcineurin inhibitors induce vasoconstriction both in vivo and in vitro, we studied whether peak serum levels of cyclosporin A led to an acute rise in renal resistance indices via the induction of intrarenal vasoconstriction. METHODS: The acute impact of peak serum levels of cyclosporin A on intrarenal resistance indices was studied in 36 patients after allogeneic renal transplantation. All patients were transplanted for > 6 months and received an immunosuppressive treatment comprising cyclosporin A. Intrarenal resistance indices were measured by duplex ultrasound immediately before (trough serum level) and 2 h after (peak serum level) the oral intake of cyclosporin A at the individual maintenance dose. RESULTS: Compared with renal resistance indices measured at trough serum levels [resistive index (RI) 0.72 +/- 0.07; pulsatility index (PI) 1.40 +/- 0.27], values remained unchanged at peak serum levels of cyclosporin A (RI 0.72 +/- 0.08; PI 1.43 +/- 0.31). Renal resistance indices correlated with the age of the patients, but not with mean arterial pressure or time since transplantation. CONCLUSIONS: The oral intake of cyclosporin A does not induce an acute rise in intrarenal resistance indices in stable transplanted patients. Thus, timing of duplex ultrasound examinations with regard to the intake of cyclosporin A is not necessary in these patients.     

Monitoring renal allograft rejection with duplex sonography

Thirty-six renal allograft recipients were monitored by serial duplex Doppler ultrasound studies post-transplant and during early rejection. A separate reproducibility study demonstrated no significant inter- or intra-operator variability in measurements of resistive index of an interlobar artery (RI) (2.1% [1.5%] and 3.2% [2.3%] respectively, mean [standard error] of coefficients of variance). Twenty-one patients had rejection within 3 weeks of transplantation. These grafts showed greater overall rises in the RI, from day 2 to day 5 post-transplant, than the grafts which had no rejection. Eleven of the 21 patients required more than one course of methyl-prednisolone for persistent or recurring rejection. These grafts had higher RI on the day rejection was diagnosed (81 [7.3], median [interquartile range]) compared with the remaining 10 patients (68.6 [8.7]). The 11 grafts with persistent rejection had higher RI (p less than 0.005, Mann-Whitney U-test) on day 2 post-transplant (76 [3.9]) compared with the 10 grafts successfully treated with a single course of methyl-prednisolone (63.2 [10.9]). This study demonstrates that grafts with an RI of greater than 70 on day 2 post-transplant are likely to have rejection requiring additional treatment (sensitivity--100%, specificity--80%). These patients may be candidates for earlier or alternative anti-rejection therapy.     

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.     

Renal artery stenosis: evaluation with colour duplex ultrasonography

Background: Detection of renal artery stenoses (RAS) by means of duplex Doppler ultrasound with direct scanning of the main renal arteries is subject to numerous limitations. Using semiquantitative analysis of the Doppler curve, which can be recorded from intrarenal arteries, it is possible to detect RAs unaffected by the problems of direct Doppler scanning of the renal arteries. Method: Both angiography of the renal arteries and colour duplex ultrasonography (US) of the intrarenal vessels (interlobar arteries) were performed in 214 patients (53.2±15.1 years) with severe arterial hypertension. Angiography was used as 'gold standard' in the diagnosis of RAS and the Doppler results were compared with the subsequent findings on angiography. At angiography, the reduction of diameter >70% was assessed as haemodynamically effective RAS. For the duplex Doppler diagnosis of RAS the following parameters were calculated: (a) resistive index (RI) of each kidney, and (b) side-to-side differences of the resistive indices (&Dgr;RI) between the right and left kidney. Results: Angiography demonstrated 59 RAS (>70%) in 53 patients, including six with bilateral RAS. By means of duplex US we found a significant difference of RI between kidneys with RAS (0.48±0.11) and without RAS (0.63±0.08; P<0.001). In addition, a significant difference of the &Dgr;RI was noted in patients with RAS (24.4%±12.5%) and the controls without RAS (3.6%±2.7%). Using a combination of both RI and &Dgr;RI, threshold values of RI=0.45 resp. &Dgr;RI=8% yields a sensitivity of 92.5% and a specificity of 95.7% in the detection of haemodynamically effective RAS. Conclusion: Colour duplex US with calculation of the RI and &Dgr;RI of intrarenal arteries is a valuable non-invasive test assessing the haemodynamic effects of RAS. Low costs and safety support the use of the Doppler technique in screening for renovascular disease.     

The use of fine-needle intrarenal manometry in the management of renal transplant patients receiving cyclosporine

The pressure inside a renal transplant can be measured by means of a fine (25-G) needle passed into the kidney, and we have shown previously that a rise in pressure to more than 40 mmHg commonly occurs during rejection episodes. A rise was not observed in patients with cyclosporine nephrotoxicity or acute tubular necrosis, so we have now used this test prospectively as part of our management of 37 patients undergoing renal transplantation. Fine needle intrarenal pressure was recorded weekly during the first three weeks after transplantation, with more frequent measures taken in patients with deteriorating or absent renal function. Treatment was dictated by the result of these tests. Deteriorating function in a kidney registering a normal pressure was diagnosed as cyclosporine nephrotoxicity and the dose of cyclosporine was reduced appropriately. A pressure reading in excess of 40 mmHg was regarded as rejection--and, after obtaining a conventional needle biopsy of the kidney, antirejection treatment was commenced immediately. Nineteen episodes of nephrotoxicity were confirmed and there was only one false-positive result. Twenty-eight of twenty-nine rejection episodes (observed in twenty-three patients) were associated with a significant rise in intrarenal pressure and were treated appropriately. In six patients who were oliguric at the time, as a result of posttransplant acute tubular necrosis, this rise in pressure was the first indication of rejection. A high pressure was recorded on the first day that the creatinine rose in two-thirds of the cases. In the remainder the pressure was seen to rise more slowly, particularly when the rejection was of the chronic vascular type and was occurring two months or more after transplantation. Fine-needle intrarenal manometry accurately identified rejection episodes in newly transplanted patients--and, because the results were unaffected by cyclosporine nephrotoxicity and acute tubular necrosis, the test was of most value in monitoring patients with these conditions.     

Role of duplex imaging and fine needle aspiration cytology of renal allografts in monitoring response to anti-rejection therapy

The role of duplex imaging and fine-needle aspiration cytology (FNAC) in monitoring the response to anti-rejection therapy was investigated in 14 of the 22 rejection episodes which occurred in 30 renal allografts recipients. In 9 of these 14 episodes of rejection, with good resolution, both resistive (RI) and pulsatility (PI) indices decreased by significant proportions (p less than 0.05). The FNAC scores also fell significantly with anti-rejection therapy. In 5 other episodes of rejection where the graft continued to deteriorate there was no significant fall of RI and PI (p greater than or equal to 0.2). In a small group of patients, both FNAC and Doppler predicted rejection. In conclusion, both duplex imaging and FNAC have a role in selection and optimal modulation of drugs in the treatment of acute renal allograft rejection.     

Early Assessment of Renal Resistance Index and Long-Term Renal Function in Renal Transplant Recipients

Background. The effect of the intrarenal arterial resistance index (RI) on long-term renal functions is not well known. We examined the predictive value of intrarenal RI on long-term allograft outcomes. Methods. We retrospectively investigated 121 stable renal transplant recipients, followed for a mean of 63.21?±?19.9 months after renal transplant. Patients with complications during the first six months after transplant were not included. Color Doppler ultrasonography was done to calculate the intrarenal RI within the first four weeks after transplant. Results. Older recipient age, high pulse pressure, active smoking, and proteinuria were associated with a higher intrarenal RI. Multivariate analyses revealed that renal RI and donor age were independent predictors of allograft outcome. Kaplan-Meier estimates of cumulative graft survival were significantly worse in patients who had an RI of 0.7 or more than they were in patients who had an RI of less than 0.7 (p?=?.005). Development of chronic allograft nephropathy (CAN) was significantly higher in patients who had an RI of 0.7 or more (p?=?.02). Conclusions. Renal RI determined within the first month after renal transplant predicts long-term allograft function and development of CAN in renal transplant recipients.     

Intrarenal manometry in the diagnosis of acute rejection superimposed on acute tubular necrosis in renal transplantation

We used fine-needle intrarenal manometry as a guide for detection of acute rejection superimposed on protracted oliguric acute tubular necrosis occurring in the postoperative course of human renal transplantation. We followed intrarenal pressure (IRP) in 31 patients who received 32 renal transplants, 12 from living related donors and 20 from cadaveric donors. There were 19 rejection episodes and 10 episodes of transient cyclosporin A (CyA) nephrotoxicity. Nine patients had posttransplant acute renal failure. Levels of IRP (mmHg) in acute rejection were (mean +/- SD) 48.6 +/- 11.1, significantly higher (p less than 0.001) than the levels in CyA nephrotoxicity (28.2 +/- 5.21), acute tubular necrosis (24.5 +/- 5.5) and normal functioning grafts (26.4 +/- 6.63). Antirejection treatment was associated with return to normal of IRP after 10 days. Intrarenal manometry was performed routinely ever 2-3 days in patients who had postoperative acute renal failure. Increments in IRP were detected on the 7-10th postoperative day in 7 patients who had 10-25 days of post-transplant oliguria. Renal biopsy findings were compatible with acute rejection, and the patients responded to intravenous bolus of steroids. We suggest that fine-needle intrarenal manometry is a reliable test for the detection of acute rejection in circumstances when traditional parameters of altered renal function cannot be evaluated.     

Renal transplant blood flow evaluation by ultrasonic duplex scanning

The transplant blood flow was measured renal transplantation by ultrasonic duplex scanner composed of pulsed Doppler flowmeter and real-time B-mode linear scanner in 32 patients. The blood flow information could be obtained from anywhere of interest within the renal transplant. Then blood flow in 3 regions including renal hilum, central echoes and renal parenchyma were measured. The parenchymal peripheral blood flow was not always similar to the hilar central blood flow. Parenchymal blood flow was the most correlated with graft function and decreased remarkably during acute rejection episode. This method enabled detection of occurrence of acute rejection in the course of post-cadaver transplant ATN. Prolongation of delta t (acceleration time) in Doppler spectrogram from parenchyma was also reliable evidence for the deterioration of graft function. Ultrasonic duplex scanning is a useful method in managing post-transplantation patients because intrarenal hemodynamics can be evaluated by this method.     

Relationship of Renal Resistive Index and Cardiovascular Disease in Renal Transplant Recipients

Background

Cardiovascular disease is the primary cause of death in renal transplant recipients, and elevated renal allograft resistive index (RI) has been associated with patient survival.

Objective

To evaluate the predictive value of intrarenal RI on atherosclerotic disease.

Patients and Methods

Ninety-seven patients who had undergone renal transplantation between 1999 and 2001 and had stable renal function were included in the study. Patients with renal artery stenosis, urinary tract obstruction, clinical symptoms of acute rejection, or chronic allograft nephropathy were excluded. Clinical and laboratory information was obtained from the medical records and included demographic data, medications used, body mass index, blood pressure, and laboratory values. Intrarenal RI and carotid intima-media thickness (IMT) were determined using Doppler ultrasonography.

Results

At linear regression analysis, RI was significantly correlated with recipient age, C-reactive protein concentration, systolic blood pressure, pulse pressure, body mass index, smoking, and carotid IMT. At multivariate linear regression analysis, only pulse pressure was an independent predictor of intrarenal RI.

Conclusion

Intrarenal RI is associated with traditional cardiovascular risk factors and carotid IMT. Elevated intrarenal graft RI may be predictive of cardiovascular disease in renal transplant recipients without complications.     

Renal scintigraphy findings in allograft recipients with increased resistance index on Doppler sonography

AIM: The measurement of intrarenal resistance indices (RIs) by doppler ultrasound plays an important role in the evaluation of renal transplant recipients. Although an elevated RI was initially considered to be specific for rejection, later studies revealed this parameter as a nonspecific marker of transplant dysfunction. In this study, we analysed Tc-99m DTPA renal scintigraphy findings in patients with increased RI during the early posttransplantation period. METHODS: This study included 22 patients with increased RI on doppler sonography during the first week after transplantation. Twenty-two recipients with uncomplicated early postoperative courses were used as a control group. An RI value >0.7 was considered pathologic. All patients underwent Tc-99m DTPA renal scintigraphy just after doppler sonography. In addition to visual interpretation of images, renogram curves were evaluated for patterns suggestive of acute tubular necrosis and acute rejection. Glomerular filtration rate (GFR) was calculated using computer software. Perfusion time-activity curves were assessed for the presence of peak and plateau patterns to calculate this ratio (P:PL). RESULTS: The mean value for P:PL in patients with increased RI and in the control group were 1.37 +/- 0.33 and 1.53 +/- 0.47, respectively (P < .05). The mean value for GFR was significantly lower in the patient group compared with control subjects. Six patients had normal perfusion and function (27%). Perfusion pattern and renogram changes were suggestive of acute tubular necrosis in 5 patients and acute rejection in 6 patients. These diagnoses were confirmed later with serial scintigraphic changes or biopsy results. Three patients had an accumulation pattern on the renogram suggesting partial obstruction. CONCLUSION: During the early posttransplantation period an increased RI on doppler sonography was seen in both normal functioning grafts and those with allograft dysfunction. Renal scintigraphy with perfusion and renogram patterns highly suggestive of specific allograft pathologies seemed to provide useful information to distinguish early postoperative renal allograft pathologies.     

A correlation between direct and indirect Doppler ultrasonographic measures in transplant renal artery stenosis

Screening for transplant renal artery stenosis (TRAS) with Doppler ultrasonography (DUS) is increasingly used in the era of kidney transplantation. Direct Doppler study of the stenotic site is a time- consuming and difficult method that requires an angle of interrogation parallel to the vessel. The aim of this study was to assess the correlation between the direct-PSVs (peak systolic velocity at the stenotic site), PSVs/PSVi (PSVi, peak systolic velocity of the adjacent iliac artery)-and indirect-intrarenal arterial resistive index (RI), perfusion index (PI), acceleration time (AT)-DUS findings in the kidney transplant recipients with TRAS. We performed 26 DUS studies of both intrarenal and main renal arteries in 19 TRAS patients (who had PSVs > 150 cm/s, PSVs/PSVi > 2). The mean values of PSVs and PSVs/PSVi were 212 +/- 44.19 cm/s and 2.77 +/- 0.77, respectively. The mean intrarenal RI, PI, and AT were 0.48 +/- 0.065, 0.70 +/- 0.12, and 177.8 +/- 54.6 msec, respectively. A significant negative correlation was found between PSVs and intrarenal RI (Pearson correlation coefficient (r) = -0.4, two-tailed P = .043). No correlation was found between intrarenal PI or AT and the direct DUS findings (P > .05). With a cutoff level of 0.55 for intrarenal resistive index, the sensitivity of this parameter to detect proximal renal arterial stenosis was about 85%. Conclusively, PSVs and intrarenal RI were negatively correlated. Intrarenal resistive index can be used as an screening measure for detection of TRAS.     

The use of duplex Doppler ultrasonography to evaluate renal allograft dysfunction

This study evaluated the utility of duplex Doppler sonograms (DS) and the resistive index (RI) in the identification and differential diagnosis of various causes of renal allograft dysfunction. The efficacy of DS and RI was studied either during acute episodes of allograft dysfunction or during periodic posttransplantation longitudinal analyses. The unique features of each renal allograft results in poor correlative value for single isolated measurements of RI. We observed that the highest RIs were in ATN and that an RI of 0.9 was not specific for acute vascular rejection. Also, an RI of 0.9 was rare in acute cellular rejection. RI could not distinguish acute rejection, chronic rejection, CsA toxicity, or obstruction, although the mean RI was significantly different from normal in these groups. Serial studies of RI did document a change at the time of a clinical event compared to baseline. It is concluded that RI is not specific to any one clinical entity.     

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.     

Effect of pulsatile left ventricular assist system implantation on Doppler measurements of renal hemodynamics in patients with advanced heart failure

The effects of left ventricular assist system (LVAS) implantation on renal hemodynamics remains to be fully elucidated. We evaluated renal function and intrarenal blood flow in five advanced heart failure patients who had been supported with a Toyobo LVAS for bridge to heart transplantation. Renal function expressed as estimated glomerular filtration rate (eGFR) was calculated using the modified formula of Modification of Diet in Renal Disease. Mean blood velocities in the bilateral segmental arteries during systolic and diastolic perfusion were measured using duplex Doppler sonography, and renal vascular resistance (resistive index [RI]) of the segmental arteries was defined as (peak systolic velocity [PSV]-end-diastolic velocity [EDV])/PSV. All studies were performed before and after implantation (mean duration of support, 15.6±10.9 months). LVAS implantation significantly improved eGFR (42.7±7.9 to 64.1±16.3mL/min, P<0.05). Beat-by-beat measurements of heart rate did not change significantly. Mean PSV decreased significantly (38.2±8.9 to 28.3±2.2cm/s, P<0.05), and mean EDV increased significantly (8.3±3.2 to 11.3±1.3cm/s, P<0.05), and thus, mean RI was significantly improved (0.79±0.06 to 0.60±0.04, P<0.01). In conclusion, in advanced heart failure patients, pulsatile LVAS implantation is associated with improved renal function, and this improvement may be mediated in part through an improvement of intrarenal hemodynamics.     

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.     

Duplex sonographic measurements in allografted kidneys: a cross-sectional study

Objectives

The measurement of color Doppler sonography indices, such as resistive index (RI) and pulsatility index (PI), can help in the evaluation of an transplanted kidney. The aim of this study was to determine the correlation between Doppler sonography indices and demographic paraclinical findings in transplanted kidneys.

Methods

A cross-sectional study was performed on 47 (27 male and 20 female) unrelated living renal transplanted patients.

Results

The mean age, body mass index (BMI), time since transplantation, pulse pressure index (PPI), intrarenal RI and PI were 38 ± 13 years, 25 ± 4.5, 48 ± 31 months, 0.34 ± 0.06, 0.69 ± 0.06, and 1.3 ± 0.3, respectively. There were significant negative correlations between time since transplantation and intrarenal RI and PI (r = −.38, P < .01; r = −.4, P < .01, respectively). There was a significant correlation between patient age, creatinine clearance, and intrarenal RI (r = .30, P = .039; r = .3, P = .043, respectively). There were no significant correlations between intrarenal RI, PI, and BMI, cyclosporine trough level, PPI, recipient and donor sexes, and rejection episodes. Diabetic patients displayed higher RI (0.76 ± 0.02 vs 0.68 ± 0.06, P = .048) and patients with serum high-density lipoprotein (HDL) level < 40 mg/dL had higher PI than patients with HDL ≥ 40 mg/dL (1.6 ± 0.4 vs 1.2 ± 0.3, P = .006).

Conclusions

Intrarenal RIs did not decrease over a few years after transplantation. They can be a useful, feasible predictor of graft function. However, future multicenter trials should be performed to prove the predictive power of RI determination as a marker of renal function.     

Improved diagnosis of early kidney allograft dysfunction by ultrasound with echo enhancer--a new method for the diagnosis of renal perfusion.

BACKGROUND: Conventional ultrasound parameters such as the resistance index (RI) are only of limited use in the diagnosis of early allograft dysfunction. We, therefore, performed a prospective study to compare the value of ultrasound contrast media (USCM) with conventional US in the diagnosis of early allograft dysfunction. METHODS: A total of 48 consecutive kidney recipients underwent US examination after USCM administration 4-10 days after transplantation. Arterial inflow was determined in the interlobar artery and renal cortex using time-intensity curve (TIC) software. The difference in time-to-peak intensity between these two vascular territories was determined, and a perfusion quotient (PQ) was defined as the ratio of TIC increase of interlobar artery to renal cortex. Three patients with segmental loss of renal perfusion demonstrated by Doppler US were excluded. RESULTS: Nineteen patients had an uneventful clinical course (control group); PQ was 1.2 +/- 0.4. Seven patients with a large perirenal haematoma, without rejection had an increased PQ (P < 0.05) and a prolonged time difference (P < 0.05). Based on clinical and histological criteria, the remaining patients were classified as acute tubular necrosis (ATN) (n = 7), non-vascular rejection (n = 7) or vascular rejection (n = 5). RI determination could not discriminate these groups. Patients with ATN (PQ = 1.6 +/- 0.7) or non-vascular rejection (PQ = 1.1 +/- 0.6) had a lower PQ than patients with vascular rejection (PQ = 2.2 +/- 0.8, P < 0.05). The time difference in all three subgroups was longer compared with controls. CONCLUSIONS: USCM might be superior in the diagnosis of early kidney allograft dysfunction compared with conventional US by means of RI determination. Perirenal haematoma, ATN and vascular rejection are associated with characteristic changes of the TIC.     

Assessment of radiocontrast media induced renal vasoconstriction by color coded duplex sonography

INTRODUCTION: Changes in renal hemodynamics are suspected to be one of the major pathogenetic correlates in radiocontrast media-induced nephrotoxicity. We investigated whether color-coded duplex sonography is an appropriate method to document changes in intrarenal vascular resistance, after intravenous injection of the low-osmolar contrast material lopamidol. METHODS: Intrarenal arterial doppler wave forms were analyzed every minute after intravenous injection of 100 mL lopamidol in 10 patients during a voiding cystourogram-procedure. The Resistive Index (RI) of each flow curve, reflecting intrarenal flow resistance, was calculated and compared to the mean of four RI measurements taken before contrast media application. RESULTS: One minute after injection of Iopamidol the RI remained unchanged compared to the baseline standard of 0.70. In measurements obtained 2, 3, 4, and 5 minutes after lopamidol injection a statistically significant rise was seen: (minute 2: 0.74, p < 0.001/minute 3: 0.75, p = 0.001/minute 4: 0.72, p =0.018/minute 5: 0.74, p = 0.031). During the further course, the resistive indices decreased progressively and showed no significant difference in comparison with the baseline standard value. CONCLUSION: Color coded duplex sonography is a simple method to detect changes in renal flow resistance after application of radiocontrast media. Based on our results, we believe that the analysis of intrarenal arterial doppler flow profiles constitutes an ideal method to investigate pathophysiologic mechanisms of radiocontrast media-induced nephrotoxicity, as well as pharmacological concepts in nephroprotectivity.     

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.