Prediction of renal allograft function with early Doppler ultrasonography

Longitudinal non-targeted metabolomic profiling of urine samples for monitoring of kidney transplantation patients

The assessment of kidney function within the first year following transplantation is crucial for predicting long-term graft survival. This study aimed to develop a robust and accurate model using metabolite profiles to predict early long-term outcomes in patient groups at the highest risk of early graft loss. A group of 61 kidney transplant recipients underwent thorough monitoring during a one-year follow-up period, which included a one-week hospital stay and follow-up assessments at three and six months. Based on their 12-month follow-up serum creatinine levels: Group 2 had levels exceeding 1.5 mg/dl, while Group 1 had levels below 1.5 mg/dl. Metabolites were detected by mass spectrometer and first pre-processed. Univariate and multivariate statistical analyses were employed to identify significant differences between the two groups. Nineteen metabolites were found to differ significantly in the 1st week, and seventeen metabolites in the 3rd month (adjusted p-value < 0.05, quality control (QC) < 30, a fold change (FC) > 1.1 or a FC < 0.91, Variable Influence on Projection (VIP) > 1). However, no significant differences were observed in the 6th month. These distinctive metabolites mainly belonged to lipid, fatty acid, and amino acid categories. Ten models were constructed using a backward conditional approach, with the best performance seen in model 5 for Group 2 at the 1st-week mark (AUC 0.900) and model 3 at the 3rd-month mark (AUC 0.924). In conclusion, the models developed in the early stages may offer potential benefits in the management of kidney transplant patients.

Predictive value of the renal resistive index in the immediate postoperative period after kidney transplantation on short- and long-term graft and patient outcomes

INTRODUCTION

During the postoperative stay in the intensive care unit after kidney transplantation, the renal resistive index (RI) is routinely measured. An increased RI, measured months posttransplant, is associated with a higher mortality. We wanted to investigate the value of the RI immediately posttransplant in predicting both short- and long-term outcome.

METHODS

We performed a retrospective single-center study. The RI was collected <48 h posttransplant in patients undergoing kidney transplantations between 2005 and 2014. Short-term outcome was evaluated by delayed graft function (DGF). The long-term endpoints were kidney function and mortality at 30 days, 1 year and 5 years.

RESULTS

We included 478 recipients, 91.4% of whom reached the end of the 5-year follow-up. A higher RI < 48 h posttransplant was significantly associated with DGF. This association was particularly strong in patients receiving grafts from donors after brain death and expanded criteria donors. A higher RI also correlated with mortality and death with functioning graft but not with graft failure. After adjustment for confounders, we found an association between increased RI and DGF, but not with long-term kidney function or mortality.

CONCLUSION

The RI routinely measured <48 h posttransplant is an independent predictor of short-term kidney function.

The role of renal resistive index as a prognostic tool in kidney transplantation: a systematic review

Background

In kidney transplant recipients (KTRs), observational data have reported conflicting findings about the utility of renal resistive index (RRI) in determining outcomes. We aimed to synthesize the current literature and determine the prognostic role of RRI in KTRs.

Methods

We conducted a systematic review to assess the role of RRI in predicting death, graft failure, graft function, and proteinuria. Of the 934 titles/abstracts reviewed, 26 studies were included. There was significant heterogeneity in RRI measurements and thresholds as well as in analytic methods and a meta-analysis could not be performed.

Results

All included studies were observational and included 7049 KTRs. Eight studies analyzed death, of which five reported a significant association with higher RRI. In the remaining three, small sample sizes and lower/multiple RRI thresholds may have limited detection of a statistically significant difference. Three studies investigated all-cause graft failure and an association with RRI was reported but varied by time of RRI measurement. Three out of five studies that analyzed a composite of patient and graft outcomes reported an association with RRI. Evidence analyzing death-censored graft failure, graft failure (unclear if death-censored or all-cause), measures of graft function, and proteinuria were conflicting. Most studies had a moderate to high risk of bias.

Conclusions

RRI likely has a prognostic role in predicting patient outcomes, reflecting patient systemic vascular disease burden rather than graft hemodynamics. Since cardiovascular diseases are a major cause of death and graft loss, RRI may be explored as a non-invasive tool to risk stratify KTRs.

Use of Intraoperative Duplex Ultrasound and Resistance Index Reduces Complications in Living Renal Donor Transplantation

BACKGROUND

The treatment of choice in end-stage renal disease is transplantation. Hemodynamic disturbances can evoke graft loss, while early ultrasound identification of vascular problems improves outcome. The aim of this study was to identify differences in postoperative complications with and without systematic intraoperative Doppler ultrasound use.

METHODS

The primary outcome was the postoperative rate of complications and the secondary aim was to find a predictive resistance index cut-off value, which would show where surgical reintervention was necessary. Over a 10-year period, 108 renal transplants were performed from living donors at our institution. In group 1 (n = 67), intraoperative duplex ultrasound and intraparenchymatous resistance index measurements assessed patients, while in group 2 (n = 41), no ultrasound was performed.

RESULTS

There were no intergroup differences in the overall postoperative complication rate or in benefit to graft or patient survival with Doppler use. However, significantly more vascular complications (10% vs 0%, P = .02) and more acute rejections (37% vs 10%) occurred in group 2 than in group 1. Therefore, an intraoperative cut-off value of the resistance index 0.5 was proposed to justify immediate surgical revision.

CONCLUSIONS

This is the first report demonstrating benefits of systematic intraoperative Doppler ultrasound on postoperative complications in renal transplantation from living donors. Our results support surgical revision with a resistance index <0.5.

Renal Doppler Resistance Indices in Kidney Transplant Recipients With Proteinuria

BACKGROUND

The onset of proteinuria in renal transplant recipients may be associated with an increased risk of allograft failure. Little is known about the relationships between factors influencing proteinuria and the Doppler ultrasound (DU) intrarenal resistive index (RI) and pulsatility index (PI) among donor recipients with proteinuria <1000 mg/24 h.

METHODS

We assessed correlations between the DU RI and PI and protein content in 93 selected renal transplant recipients: 62 patients with proteinuria 100 to 299 mg/24 h, 16 patients with proteinuria 300 to 499 mg/24 h, and 15 patients with proteinuria 500 to 999 mg/24 h. All patients underwent transplantation in a single center and were monitored by DU for at least 28 months post-transplantation.

RESULTS

The DU RI values of the proteinuria 100 to 299 mg/24 h, 300 to 499 mg/24 h, and 500 to 999 mg/24 h groups were 0.67 ± 0.05; 0.65 ± 0.04, and 0.64 ± 0.07, respectively, and the PI values were 1.21 ± 0.20, 1.10 ± 0.14, and 1.15 ± 0.22, respectively. Multivariate logistic regression analysis revealed a correlation between group 100 to 299 mg/24 h and RI values, serum creatinine, living donor (R² = 19.6%, P = .05); group 300 to 499 mg/24 h and the RI, PI values, cadaver donor (R² = 17.5%, P = .001); and group 500 to 999 mg/24 h and the RI, PI values, serum creatinine, graft survival (R² = 15.4%, P = .005).

CONCLUSIONS

Among donor recipients with proteinuria <1000 mg/24 h, DU RI values were <0.72 and PI values were <1.41 and correlations were revealed between the incidence of proteinuria and factors such as the RI, PI, and serum creatinine level.

Three-dimensional imaging of living transplanted kidney vasculature by 3D color Doppler ultrasonography

Background: It is of clinical importance to display the vasculature of transplanted kidney in three-dimensional (3D) and in non-invasive way. 3D color Doppler ultrasonographic imaging (3D-CDUI) is a non-invasive technique to display the 3D vasculature of living organs. Objective: Probe into characteristics of 3D vasculature of living transplanted kidney by 3D-CDUI, and evaluate the clinical value of 3D-CDUI on monitoring complications after operation of renal transplant. Methods: Nine patients who received allogeneic transplantation of kidney were monitored with 3D-CDUI. The instruments used included ACUSON Sequoia 512 and TomTec computer station of 3D-CDUI. Using magnetic positioning free-hand scanning, the 3D reconstruction and display of renal tissue structure and blood flow were performed off-line. Results: All patients underwent 3D-CDUI examinations without any side effect or complication. When acute rejection occurred, the 3D distribution change of renal blood flow signal could be observed clearly. During treatment of acute necrosis of renal tubules, changes of renal blood flow signal in 3D color Doppler images could be detected earlier compared with 2D color Doppler images. The position of embolized vassels could be diagnosed accurately by 3D-CDUI. Conclusion: The 3D-CDUI was helpful to improve diagnosis level of ultrasonography by monitoring complications after renal transplantation.

Relationship Between 'Immediate' Resistive Index Measurement After Renal Transplantation and Renal Allograft Outcomes

BACKGROUND

The arterial resistive index, also referred to as the resistive index (RI) or Pourcelot Index, is a measure of pulsatile blood flow. Previous studies have demonstrated the usefulness of the RI as a predictor of allograft outcomes based on RI measurement in the later stages after transplantation. However, there is little evidence of the predictive value of "immediate" RI measurement within 24 hours after transplantation.

METHODS

We performed a retrospective cohort study of 305 adult renal transplants carried out between 2003 and 2013. The associations between immediate RI measurement (within 24 hours after transplantation) and donor, recipient, and surgical factors were analyzed. In addition, the correlations between immediate RI measurement and renal allograft outcomes, including delayed graft function (DGF) and transplant failure (TF), also were evaluated.

RESULTS

From a cohort of 305 patients, 52 were excluded on the basis of on confounding factors. Of the remaining 253 patients, the mean age was 48.4 years, 57.5% were male, and approximately one-third had diabetes. Two hundred twenty-six patients had an RI < 0.8, whereas only 27 had an RI ≥ 0.8. Significant associations were found between elevated RI (≥0.8) and both DGF (odds ratio = 3.22, P = .006) and TF (odds ratio = 3.54, P = .008).

CONCLUSIONS

Immediate RI measurement after renal transplantation is a strong predictor of both DGF and TF.

The predictive value of resistive index obtained by Doppler ultrasonography early after renal transplantation on long-term allograft function

DUSG is a useful diagnostic tool for the follow-up of renal transplant recipients. The measurement of intrarenal arterial RI by DUSG has been proven to predict short-term AF. The aim of the study was to evaluate the predictive value of DUSG performed during the early after RTx on long-term AF. Seventy patients were enrolled into study. DUSG was performed at third and seventh days after RTx. Patients were divided into two groups according to rate of recovery of graft function as patients with normal graft function and abnormal graft function. Although the RI values were correlated with the AF early after transplantation, they were not correlated with long-term AF. However, the rate of recovery of graft function at early period after RTx was correlated with creatinine level at first year and with glomerular filtration rate at first year and last visit. Although the RI has no predictive value for long-term AF, the rate of recovery of graft function at early post-transplantation period has predictive value for long-term AF; patients with higher RI values early after RTx should be followed carefully for the development of chronic allograft injury.

The inability of an early post-transplantation intrarenal resistive index to predict renal allograft function at 12 weeks after engraftment in young adults

Background The intrarenal resistive index (RI) is a promising tool for predicting renal graft outcomes. Due to the complexity of graft function and the presence of diverse contributing factors, however, the available data are inconclusive. Purpose To examine the performance of the RI 1 week after transplant in predicting allograft function at week 12, with an emphasis on the type of intrarenal artery used in the examination. Material and Methods A total of 58 first-time living-donor kidney-allograft-transplantation patients aged less than 50 years underwent Doppler ultrasonography (US) of the intrarenal arteries 1 week after engraftment. The RI was calculated for both the segmental (RI-C) and interlobar-arcuate (RI-P) arteries. Serum creatinine level and the creatinine reduction ratio (CRR) were determined at weeks 1 and 12 post transplantation. Results While the RI did not correlate with serum creatinine level and CRR at week 1, significant correlations were present between the RI and serum creatinine level (r = 0.28, P = 0.03 for both RI-C and RI-P) and CRR (r = -0.25, P = 0.05 for both RI-C and RI-P) at week 12. The sensitivity, specificity, positive predictive value, and negative predictive value of using RI-C in predicting abnormal 12-week serum creatinine level were 51.2%, 52.9%, 72.4%, and 31.3%, respectively; and 53.7%, 47.1%, 70.9%, and 29.6% for RI-P, respectively ( P > 0.99 for all comparisons). Conclusion Early post-transplantation RI correlates significantly with both serum creatinine level and creatinine reduction ratio 12 weeks after engraftment with intermediate predictive accuracy.

High Resistive Index in Transplant Kidneys Is a Possible Predictor for Biopsy Complications

BACKGROUND

Transplant kidney biopsies are performed to determine a histological diagnosis for specific patient treatment. The aim of this study was to investigate if Resistive Index (RI) could be a predictor for biopsy complications.

METHODS

In this study, 220 consecutive transplant kidney biopsies (136 men and 84 women; median age, 55.5 years) were prospectively included. RI (median, 0.7) was measured by use of ultrasound. Histological diagnoses and biopsy complications were registered. Biopsy needles were either 16- or 18-gauge. Biopsies were performed by radiologists and were carried out as an outpatient procedure (70%) or an inpatient procedure (30%). Usually three passes per biopsy were performed.

RESULTS

The overall complication rate was 6.8%, divided into major (4.5%) and minor (2.3%) complications. An RI ≥0.8 predicts major (13.3% versus 3.2%; risk ratio [RR], 4.2; confidence interval [CI], 1.3-14.1; P = .03) and overall biopsy complications (16.7% versus 5.3%; RR, 3.2; CI, 1.2-8.6; P = .04) compared with RI <0.8. In the group <0.8, RI correlated with age (r_s = 0.28, P < .001) and systolic blood pressure (r_s = 0.18, P = .02). In the group ≥0.8, RI correlated with degree of interstitial fibrosis (r_s = 0.65, P = .006) and systolic blood pressure (r_s = 0.40, P = .03). The multiple regression analysis showed that in the group <0.8, the RI correlated only with age (P < .001), whereas in the group ≥0.8, RI correlated only with the degree of interstitial fibrosis (P = .003).

CONCLUSIONS

An RI ≥0.8 indicates greater risk for major and overall biopsy complications and should result in greater caution after biopsy.

Measurement of Internal and External Pressure of Transplanted Kidney: An Underestimated Method of Diagnosis for Renal Grafts

Hardness, or tensity (tonus), of transplanted kidney can change in the course of various pathologic conditions. Manual examination (with palpation), which is most frequently used to evaluate this transplanted organ, is not objective. First attempts of objective evaluation were described in the medical literature in the 1980s. They consisted of evaluation of intrarenal pressure by puncturing the kidney, connecting an intravenous drip line, and measuring the pressure in centimeters of water column. Examination of a group of subjects revealed significant differences in mean measurements, especially in patients with acute rejection process compared with the control group. However, use of this method was not continued, owing to its invasiveness. Our own diagnostic method, described here, is measurement of external kidney pressure (tonus). Two types of devices (tonometers) are described, as well as a project of a future tonometer functioning on the basis of electronically measured differences in values of forces used above the graft and above the symmetric part of the abdomen causing identical deflection of abdominal wall. Thirty-two patients (including control group) were examined with the use of this method. Statistically significant differences were revealed between patients with acute graft rejection and chronic graft nephropathy compared with the control group. The method described here can be a valuable supplement to other currently used noninvasive means of renal graft evaluation, including ultrasonography, Doppler, and elastographic examinations.

Role of color Doppler ultrasound in the evaluation of renal transplantation from living donors

PURPOSE

The aim of this study was to evaluate the same kidney before and after transplantation to assess the ability of the allograft to restore blood flow, time required to achieve functional recovery after surgery and the possibility of differentiating normal from pathological allografts using color Doppler ultrasound (CDUS) flow indices: resistive index (RI)/renal cortical ratio (RCR) and scintigraphy.

MATERIALS AND METHODS

79 living donors and 79 recipients. Donors underwent renal CDUS and scintigraphy. CDUS was repeated on the allograft 24 h, 3, 15 and 30 days after transplantation, and scintigraphy 3-5 days after transplantation. Recipients were divided into two groups on the basis of clinical and biochemical values: (A) well-functioning allografts and (B) acute pathology. Results of CDUS, RI and RCI were compared to results of scintigraphy, biochemical values and biopsy.

RESULTS

Group (A) n = 60 (76 %), group (B) n = 19 (24 %); RI sensitivity was 93 %, specificity 83 %. In group (A) positive predictive value (PPV) was 94 % and in group (B) 90 %. RCR using receiver operating characteristic curve analysis yielded sensitivity 100 % and specificity 98.3 %. Scintigraphy mean values of glomerular filtration ratio and T max before transplantation were in group (A): 50.32 ml/min and 4.87 min; after transplantation 46.88 ml/min and 4.96 min; in group (B): 48.68 ml/min and 4.63 min, after transplantation 27.89 ml/min and 10.53 min, respectively. Pearson's correlation coefficient between preoperative and postoperative results of scintigraphy was significant in group (A) (glomerular filtration ratio = 0.85, T max = 0.70) and not significant in group (B) (glomerular filtration ratio = 0.40, T max = 0.08).

CONCLUSION

This study shows that CDUS, RI and RCR are useful in postoperative evaluation of transplanted kidneys as these parameters can, after only 24 h, confirm the good condition of the allograft despite still excessive blood parameter values.

Relation of resistive and pulsatility indices with graft function after renal transplant

OBJECTIVES

There are conflicting data regarding the use of some measured indices by Doppler ultrasound such as the resistive index and the pulsatility index in predicting renal allograft dysfunction. This study sought to evaluate the association of early postoperative Doppler indices and 3-month serum creatinine levels in renal transplant recipients.

MATERIALS AND METHODS

During a 1-year period, all patients who underwent renal transplant at our hospital were recruited into a prospective study. Doppler ultrasound was performed on all patients 6 days and 3 months after the transplant and the resistive index and the pulsatility index were calculated for each patient. Then, the association between these indices and 3-month outcomes of patients were investigated.

RESULTS

Thirty-eight patients including 21 men (mean age, 36.6 ± 13.1 y) were evaluated. There was a positive correlation between the resistive index and the pulsatility index at 6 days after transplant and the serum creatinine measured at the same day (P < .001 and r=0.570 for resistive index; P < .001 and r=0.547 for pulsatility index). There was also a positive correlation between the pulsatility index and the resistive index at 6 days after transplant and 3-month serum creatinine level (P = .009 and r=0.420 for resistive index; P = .009 and r=0.417 for pulsatility index). There were negative correlations between the resistive index and the pulsatility index on the sixth day after surgery and creatinine clearance measured at 6 days and 3 months after transplant.

CONCLUSIONS

This study reveals a strong-to-medium correlation between the resistive index and the pulsatility index, serum creatinine level, measured 6 days after transplant.

Color Doppler indexes in early phase after kidney transplantation and their association with kidney function on six month follow up

BACKGROUND

Doppler ultrasonography (DU) and measurement of its indexes, resistive index (RI) and pulsatility index (PI), is used to investigate transplanted kidney hemodynamic status and function. The aim of this study was to determine the correlation between Doppler indexes in the early phase after transplantation with long-term transplanted kidney function.

MATERIALS AND METHODS

In this cross-sectional study on 38 newly kidney transplant patients, we performed DU with assessment of its indexes within 48 hours, 1 week, and 6 months after kidney transplantation. Serum creatinine after stability and 6 months after kidney transplantation were assessed. Cyclosporine level was measured 1 week after kidney transplantation and compared with DU indexes.

RESULTS

About 71% of kidney transplanted patients reached their normal initial creatinine level(cr<1.5 mg/ dl) and 28% of all patients were involved in kidney dysfunction after 6 months (increase in basic creatinine level more than 25%).There was no significant difference between mean RI and PI in patients with normal and disturbed kidney function based on creatinine level in early posttransplantation period but there was linear correlation between mean RI and PI within 48 hours and 1 week with kidney function after 6 months. Also no association between cyclosporine level and RI and PI was shown. There was a direct association between age and the levels of RI and PI 6 months after transplantation.

CONCLUSION

This study suggests assessment of RI and PI in early period after transplantation and can be used as predictive parameters for long-term function of transplanted kidney and RI more than 0.80 in early phase after transplantation has an acceptable sensitivity and specificity to predict long-term kidney dysfunction.

Renal transplant ultrasound: a pictorial review

Renal transplantation is considered the optimal treatment in patients with end-stage renal disease. Ultrasound is usually the first choice imaging modality for evaluating renal transplant anatomy and perfusion. It is important to be aware of how to image a renal transplant, the normal sonographic appearances and relevant pathological processes. Renal transplant ultrasound imaging includes duplex vascular evaluation and the operator must have a sound knowledge of both normal and abnormal Doppler waveforms. Complications following renal transplantation are usually assessed with ultrasound. The time frame in which complications can occur stretches from the immediate postoperative period to months or years following transplantation. A knowledge of the anticipated complications relative to that timescale helps to focus the examination. This pictorial review aims to demonstrate the appearances of the normal renal transplant as well as potential complications. These include vascular (renal vein thrombosis, renal artery stenosis, pseudoaneurysm and arteriovenous fistulae), parenchymal (acute rejection, acute tubular necrosis and malignancy) and urological (ureteric stricture and renal calculi) complications.

Impact of early kidney resistance index on kidney graft and patient survival during a 5-year follow-up

BACKGROUND

Resistance index (RI) measured by Doppler sonography during the early post-transplant period reflects interstitial oedema within the transplanted kidney. We have prospectively analysed the relationship between RI measured shortly after kidney transplantation (KTx), patient and graft survival, as well as kidney graft function during a 5-year follow-up.

METHODS

RI was measured at the second to fourth day after KTx in 364 consecutive patients, who were divided into tertiles, according to baseline RI value (Group 1: RI < 0.73, Group 2: RI between 0.73 and 0.85 and Group 3: RI > 0.85). The kidney graft function [estimated glomerular filtration rate (eGFR)] during the follow-up period was calculated according to the Modification of Diet in Renal Disease formula.

RESULTS

During the 5-year follow-up period, 23 patients died (2.6 versus 6.5 versus 9.6% in RI tertiles, respectively) and 59 lost their kidney graft (12.1 versus 17.7 versus 18.4%, respectively). Survival analyses showed that the effect of RI was significant for a combined outcome [graft loss or death; hazard ratio (HR) = 10.88] and in relation to death, it was of borderline significance (HR = 45.3, P = 0.09). The effect of delayed graft function (DGF) was only significant on graft loss (HR = 1.73). eGFR in the highest tertile was lower than in the lowest tertile during the entire follow-up period.

CONCLUSIONS

High RI values measured in segmental arteries in the very early post-transplant period predict worse kidney graft function and increased risk of all-cause graft loss, including patient death in the 5-year follow-up period. (ii) The predictive value of RI is not completely independent from the adverse influence of DGF on the premature graft loss.

Prognostic impact of renal arterial resistance index upon renal allograft survival: the time point matters

BACKGROUND

The renal arterial resistance index (RI) is reported to be a significant predictive parameter for renal allograft failure or death. The influence of the time point after renal transplantation on its predictive power has not been sufficiently evaluated. We performed a retrospective analysis of RI and its power to predict renal allograft failure or death with special emphasis on the time point of RI measurement.

METHODS

The present analysis is based on ultrasonographically recorded intrarenal arterial RI measurements, routinely obtained in our outpatient department, over a period of 13 years. Altogether, 88 patients with an RI measurement 0-3, 3-6 and 12-18 months after transplantation were included and retrospectively stratified into two groups according to the RI: those with an index >0.75 and those with an index of ≤0.75.

RESULTS

Twenty patients (23%) reached the combined end point, i.e. allograft failure with a return to dialysis or death. The RI measured early after transplantation (0-3 and 3-6 months) did not predict the end point, whereas the RI obtained between 12 and 18 months showed a significant predictive value for renal transplant failure or death in a univariate approach [Wald test, P = 0.0013, hazard ratio (HR) 4.787, 95% confidence interval (CI) 1.846-12.411]. At 12-18 months after transplantation, 14% (12 patients) of the study population had an RI >0.75. Seven (58%) of these patients reached the end point versus 13 of 76 patients (17%) with an RI ≤0.75. In a multivariate Cox model, the RI measured between 12 and 18 months after transplantation exhibited the highest hazard ratio (HR 6.191, 95% CI 2.288-16.756, P = 0.0003) for transplant failure or death.

CONCLUSION

In our hands, the RI obtained during the first 6 months after transplantation failed to predict renal allograft failure or death, whereas the RI measured 12-18 months after transplantation appeared useful to predict long-term allograft outcomes.

Doppler parameters in renal transplant dysfunction: correlations with histopathologic changes

OBJECTIVES

The aim of this study was to assess the relationship between intrarenal Doppler parameters and histopathologic changes shown on kidney biopsy in renal transplant dysfunction.

METHODS

We retrospectively reviewed the records of 113 patients (61 men and 52 women; age range, 22-76 years; mean age ± SD, 50.9 ± 12.7 years) who underwent both transplanted kidney sonography and biopsy from May 1, 2007, to May 31, 2009. Doppler parameters of the interlobar arteries, including the peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI), were compared with kidney biopsy findings. According to histopathologic findings, the 113 patients were divided into two groups: 1, interstitial fibrosis/tubular atrophy and vascular/glomerular sclerosis (n = 79); and 2, edematous changes in glomeruli without fibrosis (n = 34). The correlations between Doppler parameters and histopathologic findings were statistically analyzed.

RESULTS

There were statistically significant differences in the PSV and EDV of the interlobar arteries between groups 1 and 2. Both the PSV and EDV in group 1 were significantly lower than those in group 2 (P < .001). There was no significant difference in the RI of the interlobar arteries between the two groups (P > .05). There were no significant differences in the PSV, EDV, and RI of the main renal artery between the two groups (all P > .05).

CONCLUSIONS

The PSV and EDV of the interlobar artery have statistical correlations with histopathologic types in renal transplant dysfunction. Both the PSV and EDV in interstitial fibrosis/tubular atrophy and vascular/glomerular sclerosis seem lower than those in glomerulopathy without fibrosis. Hence, the PSV and EDV of the interlobar artery may potentially be used as hemodynamic indicators for monitoring the progress of renal transplants.

Impact of herniorraphy technique on testicular perfusion: results of a prospective study

BACKGROUND

Inguinal hernia repair is one of the most frequently performed operations. The Lichtenstein hernia repair is the most popular hernia repair technique in general surgical practice. However, totally extraperitoneal-preperitoneal hernia repair technique has been frequently used technique recently. The aim of this prospective, randomized, clinical study was to evaluate testicular perfusion after these 2 procedures.

METHODS

In our prospective randomized study, 32 male patients, aged 33 to 72 years who fulfilled the inclusion criteria underwent elective herniorraphy for groin hernia. The patients were randomly assigned into either Lichtenstein hernia repair (n=16) or totally extraperitoneal-preperitoneal hernia repair (n=16) group according to their admittance. Color Doppler ultrasonography of the testes was performed on all patients 1 day before the operation, 3 days and 6 months after the operation.

RESULTS

The results of the resistive index of the both groups; Lichtenstein hernia repair and totally extraperitoneal-preperitoneal hernia repair are statistically insignificant in all preoperative, early and late postoperative periods (P>0.05).

CONCLUSIONS

Either Lichtenstein hernia repair or totally extraperitoneal-preperitoneal hernia repair does not effect the testicular perfusion.

Parameters of Doppler ultrasound at five days posttransplantation as predictors of histology and renal function at one year

INTRODUCTION

In our center, a Doppler ultrasound (DU) is performed at 5 days after transplantation. The normal upper limit of flow velocity (FV) in the renal artery is 200-250 cm/s. The resistance index (RI) is considered elevated when >0.8. Elevation of the RI can be shown in all the forms of graft dysfunction.

OBJECTIVE

The objective of this study was to evaluate the capacity of the DU to predict the prognosis of graft function and histological damage at 1 year.

METHODS

We examined a retrospective cohort of patients undergoing renal transplantation between January 2004 and May 2007. The renal function was evaluated with serum creatinine measurements and glomerular filtration rate (GFR) estimates by the quadratic Modification of Diet in Renal Disease study equation. The biopsy specimen was evaluated according to the Banff 1997 classification.

RESULTS

The overall average age was 35 years, and 58% of the subjects were men. Eight cases (25.8%) showed abnormal DU. The Delta among those with normal DU was -0.94 versus 0.27 +/- 0.39 with abnormal DU (P < .005). There was no significance as far as the biopsy at 1 year.

CONCLUSIONS

Renal DU allows physicians to suspect complications at the first posttransplantation year. It shows a tendency to elevated blood pressure, as well as increased deterioration of renal function over the first year.

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.

Prediction of the severity and outcome of acute tubular necrosis based on continuity of Doppler spectrum in the early period after kidney transplantation

BACKGROUND

Doppler flow spectrum, quantified in the segmental arteries of the graft early after kidney transplantation (KTx), reflects the exacerbation of interstitial oedema. In some patients, the spectrum is characterized by the absence of blood flow during part or during the whole diastole of the cardiac cycle. We have previously observed that such discontinuous flow is associated with a more severe clinical course of acute tubular necrosis (ATN). In order to further verify this hypothesis, we have quantified prospectively the timing of blood flow in Doppler spectrum within the cardiac cycle.

METHODS

Doppler sonography was performed in 173 recipients between 2 and 4 days after KTx. A total of 18 patients with a diagnosed episode of acute rejection or primary graft non-function were excluded from the analysis. Fifty-three out of 155 patients (34%) developed ATN, defined as a requirement for more than one haemodialysis session after KTx. In patients with a discontinuous spectrum of flow, we have quantified the ratio of time during the whole cardiac cycle in which the flow is present [flow time index (FTI) expressed as %].

RESULTS

The discontinuous spectrum of flow was present in 35 out of 53 (66.0%) patients with ATN but only in 6 out of 102 (5.9%) patients with immediate or slow graft function. The relative risk of ATN occurrence for patients with discontinuous spectrum of flow was 5.98 (3.83-9.34) and the duration of ATN in these patients was twice as long-12 (10-14) versus 6 (5-8) days. In patients with ATN a significant correlation was found between FTI and duration of ATN (r = -0.357, P = 0.035).

CONCLUSION

The discontinuous spectrum of flow in the segmental arteries of the kidney graft in the early period after KTx is typical for ATN and predicts its duration.

Impact of slit and nonslit mesh technique on testicular perfusion and volume in the early and late postoperative period of the totally extraperitoneal preperitoneal technique in patients with inguinal hernia

AIMS

Using slit and nonslit mesh in laparoscopic totally extraperitoneal preperitoneal (TEPP) inguinal hernia repair are well-known approaches. The aim of this prospective, randomized, clinical study was to assess testicular perfusion after these procedures.

METHODS

In the study period, 40 male patients with unilateral inguinal hernia were assigned into 2 equal groups as follows: slit (S) and nonslit (NS). TEPP hernia repair was performed in all patients. In the 2 groups, testicular arterial blood flow and testis volumes were measured by Doppler ultrasonography preoperatively, on the 5th postoperative day, and 6 months postoperatively, respectively.

RESULTS

No statistically significant difference was found between the preoperative, 5th day postoperatively, and 6-month arterial resistance index (ARI) results when comparing the S and NS groups in ultrasonographic testicular blood flow studies. There was no statistically significant difference of testicular volume between the preoperative period, the 5th postoperative day, and 6 months postoperatively in the 2 groups.

CONCLUSIONS

According to the results, no statistically significant difference was found in terms of testicular perfusion and volume between those 2 methods of TEPP repair for inguinal hernia.

Vascular complication and Doppler ultrasonographic finding after renal transplantation

OBJECTIVES

Vascular complications are common after renal transplantation. In this study we correlated Doppler sonographic indices and transplant kidney function.

METHODS

We reviewed data on 244 renal transplant patients. Doppler ultrasonographic evaluation was performed during the first 2 weeks after renal transplantation. We determined resistive index (RI) and pulsatility index (PI) in the interlobar arteries and thrombosis of renal and lower limb veins. Serum creatinine (Cr) and cyclosporine levels were evaluated prior to sonographic assessment.

RESULTS

The mean age of the 142 male and 102 female patients was 36.31 +/- 3.30 years. Prevalence of real artery stenosis was 9.5%. In these patients the mean serum Cr level (2.21 +/- 1.83 mg/dL) was significantly higher than among patients with patent renovascular tributary (1.49 +/- 1.00 mg/dL; P=.03). RI and PI were also significantly correlated with serum Cr(P=.05 and .001, respectively). There was no relationship between cyclosporine level or panel-reactive antibody with RI and PI. Retransplant patients showed higher RI than first renal allograft recipients (0.72 +/- 0.16 vs 0.63 +/- 0.11; P=.006). Serum Cr level was higher among renal allograft recipients with Doppler evidence of thrombosis of the lower limb veins (3.1 +/- 0.98 mg/dL versus 1.56 +/- 1.13 mg/dL; P=.04).

CONCLUSIONS

RI and PI are two valuable Doppler ultrasonographic markers to determine renal allograft function and related vascular complications.

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 >or= 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.

Inguinal hernia repair protects testicular function: a prospective study of open and laparoscopic herniorraphy

BACKGROUND

Despite the frequency of open and laparoscopic herniorraphy the effect of the hernia and subsequent repair on testicular function is unknown. Our objective was to determine if there is an association between inguinal hernia and hernia repair on testicular function.

STUDY DESIGN

Thirty-seven men aged 18 to 70 years were enrolled in a prospective internally controlled cohort study. They underwent Doppler ultrasonography and serum testicular hormone analysis pre- and post- either open Lichtenstein's repair or laparoscopic totally extraperitoneal hernioplasty. These surrogates of testicular function were measured up to 6 months postrepair.

RESULTS

Thirty-seven consecutive patients underwent either Lichtenstein (n = 17) or totally extraperitoneal hernioplasty (n = 20) hernia repair as per surgeon preference. Preoperatively there was a significant elevation in the sonographic resistive index (RI) in the affected (hernia) side compared with the normal side (0.601, 0.569; p < 0.001). This elevation in RI was reversed posthernia repair at a median followup of 6.1 months. Inguinal hernia or repair did not affect testicular volume. The choice of either Lichtenstein or totally extraperitoneal hernioplasty hernia did not significantly alter the testicular function.

CONCLUSIONS

Patients with inguinal hernia have an elevated testicular vascular resistance, which is reversed after repair. The choice of laparoscopic or open herniorraphy did not affect reversal of this surrogate of testicular function.

Early assessment of renal resistance index after kidney transplant can help predict long-term renal function

BACKGROUND

Color Doppler ultrasonography of intrarenal arterial resistance index (RI), performed early after kidney transplant, has proven to reliably predict short-term allograft function. The aim of this study was to assess whether it could also predict long-term renal function.

METHODS

We retrospectively analysed 76 kidney transplant patients who underwent RI assessment within 1 month after the transplant, subdivided into two groups according to RI values, lower (group A) or higher (group B) than its median value (0.635).

RESULTS

Compared with group A subjects, the patients of group B were older at the time of transplant (42 +/- 9 vs 35 +/- 8 years; P = 0.001), the donor age was also older (41 +/- 16 vs 33 +/- 13 years; P = 0.02) and had a slightly higher proteinuria (0.54 +/- 0.5 vs 0.32 +/- 0.2 g/24 h; P = 0.02). Serum creatinine, ciclosporin or tacrolimus trough level, arterial blood pressure, number of human leukocyte antigen (HLA) mismatches, anti-hypertensive medications and incidence of delayed graft function were not significantly different between the two groups. By univariate analysis, RI turned out to directly correlate with the recipient age, donor age and daily proteinuria (P = 0.007, P = 0.0007 and P = 0.02, respectively). Multivariate analysis showed that only donor and recipient age maintained their independent predictive value on RI. Kaplan-Meier analysis, considering a serum creatinine increase >50% as the endpoint of the study, showed a statistically significant different graft survival in the two groups (log-rank test = 5.489; P = 0.01). The univariate relative risk of deterioration of graft function among patients with higher RI was 3.77. Proteinuria and recipient age increased the risk as well.

CONCLUSIONS

Our data seem to suggest that early determination of RI can help predict long-term graft function in kidney transplant recipients.

Tissue Pulsatility Index: A New Parameter to Evaluate Renal Transplant Perfusion

BACKGROUND

: Chronic allograft nephropathy (CAN) is characterized by loss of parenchymal perfusion. We applied therefore the novel parameter Tissue Pulsatility Index (TPI) to quantify transplant perfusion in the long-term surveillance of renal transplants.

METHODS

: Color Doppler sonographic videos of renal transplants from 38 renal transplant recipients were recorded under defined conditions. TPI was calculated as ratio of the difference of mean systolic and diastolic velocities of the entire region and the average velocity.

RESULTS

: TPI was significantly different between the proximal and distal cortical layers (1.12 vs. 1.56, respectively P=0.000). In patients with elevated creatinine as a measure of compromised function, significantly (P=0.016) higher values (TPI=1.70) were found at distal cortical level compared to patients with normal creatinine (TPI=1.34). After transplantation, TPI rises significantly: 1.10 in 0-1 years vs. 1.41 in 1-2.9 years, P=0.002; 1.10 in 0-1 years vs. 1.37 in 3-4.9 years, P=0.000; 1.10 in 0-1 years vs. 1.31 in 7-8.9 years, P=0.049). TPI declines later on in our population to significantly lowered values in the group more than 9 years after transplantation (1.10 in 0-1 years vs. 0.94 in >9 years, P=0.044).

CONCLUSION

: With the novel TPI, we could demonstrate significant differences between proximal and distal cortical perfusion, between compromised and well-functioning transplants, and could observe significant changes of transplant perfusion at various points at the posttransplantation time scale.

The Intrarenal Vascular Resistance Parameters Measured by Duplex Doppler Ultrasound Shortly After Kidney Transplantation in Patients With Immediate, Slow, and Delayed Graft Function

BACKGROUND

Evaluation of pulsatility (PI) and resistive (RI) indexes by duplex Doppler ultrasound shortly after kidney transplantation reflects the exacerbation of interstitial edema. The aim of study was to characterize factors that influence PI and RI in patients with immediate (IGF), slow (SGF), or delayed (DGF) kidney graft function.

PATIENTS AND METHODS

PI and RI were measured in 200 transplanted patients at 2 to 4 days postoperatively. We excluded patients with acute rejection episodes within the first month. IGF, which was defined as serum creatinine <264 micromol/L at 3 days, SGF, which was defined as creatinine >264 micromol/L by day 3 with a maximum of one dialysis, and DGF, which was defined as more than 1 dialysis were observed in 33.3%, 41.5%, and 25.2% of patients, respectively. The examined donor parameters were age, hypotensive episodes, catecholamine infusion, central venous pressure, and glomerular filtration rate. The recipient factors were age, history of hypertension, diabetes mellitus, ischemic heart disease, and stroke. Additionally cold ischemia time (CIT), HLA mismatch, and PRA were analyzed.

RESULTS

The lowest PI and RI values were observed among patients with IGF (PI 1.37 [1.28 to 1.46]; RI 0.72 [0.69 to 0.74]); moderate values in SGF (PI 1.65 [1.52 to 1.78]; RI 0.78 [0.76 to 0.80]) and the highest values in DGF (PI 2.09 [1.83 to 2.35]; RI 0.83 [0.80 to 0.86]) differences that were highly significant. Hypotensive episodes and catecholamine infusion in the preharvest period had essential impacts on PI or RI values in the early posttransplant period. There was no significant correlation between PI or RI values and CIT. A slower ATN resolution was observed in DGF patients with higher PI values.

CONCLUSION

Ischemic injury, which occurred mainly prior to organ harvesting, played a dominant role determining intrarenal resistance in the early posttransplant period.

Renal Artery Resistance Index, Thyroid Hormones, and Thyroid Volume in the Early Kidney Transplants Recipients

BACKGROUND

Thyroid hormones could affect renal function, and, on the other hand, renal dysfunction may affect thyroid function. Disturbances of concentrations of thyroid hormones are often associated with thyroid gland enlargement. The aim of the study was to assess the function and morphology of the thyroid (volume and hormones concentration) and kidney function after transplantation (creatinine concentration and resistance index [RI] of transplant artery).

MATERIAL AND METHODS

The group included 13 females, 19 males; aged 19-69 years, mean 44.75 +/- 14.8 years after transplantation with stable graft function. Thyroid volume, renal artery RI, creatinine concentration, and concentrations of T3, rT3, FT3, FT4, and TSH were estimated the day before surgery, and at 1, 3, 6, and 10 days after transplantation.

RESULTS

The statistical analysis revealed a negative correlation between delta RI (difference between RI at 3 and 6 days after transplantation) and serum creatinine concentration, 10 days after transplantation (r = -0.63; P < 0.01). We also observed a negative correlation between creatinine serum concentration at 10 days after transplantation and delta thyroid volume (Delta Vol; r = - 0.48; p < .05), a positive correlation between delta FT4 (Delta FT4) serum concentration, and delta creatinine (Delta Crea; r = 0.73; P < .001).

CONCLUSIONS

The dynamics of RI changes in the transplant kidney artery between 3 and 6 days after transplantation may predict graft function. Together with improved kidney function at 10 days after transplantation, we observed a regression of goiter.