Association between Early Resistive Index Measurement and Early Graft Function and Long-Term Graft Survival after Kidney Transplantation: an Evidence-based Clinical Review

BACKGROUND

resistive index (RI) is highly utilised to assess the graft function using Doppler ultrasonography. The RI has been shown as the best ultrasound parameter to assess kidney allograft dysfunction. Several studies have established the role of the RI as a predictor of transplant failure. However, these studies were using RI measurement in the later stages post transplantation. The present study has conducted to identify the association between early RI measurement and early graft function represented as delayed graft function (DGF) and immediate graft function (IGF), as well as long-term graft survival.

METHODS

an evidence-based clinical review of studies published before May 2018 was conducted from Medline, Science Direct, EMBASE and Cochrane databases. Studies on early measurement of RI whereby the primary or secondary goals of the study related to graft function and/or graft survival were included. Studies using late RI measurement and without RI value groups were excluded. The Mantzel-Haenzel method was used to analyse pooled risk ratio and 95% confidence interval, while the heterogeneity of the study was calculated through I2 value. Data analysis was performed using Review Manager 5.3.

RESULTS

nine studies with a total of 1802 patients who had undergone a kidney transplant were analysed. DGF was found in 19% (193/1015) of the low RI group and in 42.8% (337/787) of the high RI group (RR 2.04 (95% CI 1.72 - 2.41), p < 0.00001, I2 = 28%). IGF was found in 39.5% (62/157) of the low RI group and in 10.5% (28/268) of the high RI group (RR 0.26 (95% CI 0.17 - 0.40), p < 0.00001, I2 = 0%). Long-term graft survival, with follow up between 60-144 months, was found in 83% (701/845) of the low RI group and in 69.4% (395/569) of the high RI group (RR 0.82 (95% CI 0.72 - 0.93), p = 0.002, I2 = 63%).

CONCLUSION

the results of this study emphasise the association between early measurement of RI and early graft function, and long-term graft survival. An elevated RI provides the chance of recognizing the patients with poor long-term prognosis, from the first moment after kidney transplant.

Can transplant renal scintigraphy predict the duration of delayed graft function? A dual center retrospective study

Introduction

This study focused on the value of quantitatively analyzed and qualitatively graded renal scintigraphy in relation to the expected duration of delayed graft function after kidney transplantation. A more reliable prediction of delayed graft function duration may result in a more tailored and patient-specific treatment regimen post-transplantation.

Methods

From 2000 to 2014, patients with early transplant dysfunction and a Tc-99m MAG3 renal scintigraphy, within 3 days post-transplantation, were included in a dual center retrospective study. Time-activity curves of renal scintigraphy procedures were qualitatively graded and various quantitative indices (R20/3, TFS, cTER, MUC10) were combined with a new index (Average upslope). The delayed graft function duration was defined as the number of days of dialysis-based/functional delayed graft function.

Results

A total of 377 patients were included, with a mean age (± SD) of 52 ± 14 years, and 58% were male. A total of 274 (73%) patients experienced delayed graft function≥ 7 days. Qualitative grading for the prediction of delayed graft function≥ 7 days had a sensitivity and specificity of respectively 87% and 65%. The quantitative indices with the most optimal results were cTER (76% sensitivity, 72% specificity), and Average upslope (75% sensitivity, 73% specificity).

Conclusions

Qualitative renal scintigraphy grading and the quantitative indices cTER and Average upslope predict delayed graft function ≥ 7 days with a high sensitivity. This finding may help to support both clinicians and patients in managing early post-operative expectations. However, the specificity is limited and thus renal scintigraphy does not reliably help to identify patients in whom the course of delayed graft function is longer than anticipated.

Perfusion of kidney graft pyramids and cortex in contrast-enhanced ultrasonography in the determination of the cause of delayed graft function

BACKGROUND

The aim of this study was to assess the usefulness of a new ultrasound technique - contrast-enhanced ultrasound examination (US-CE) - using sulphur hexafluoride in the early post-transplant assessment of graft perfusion. Time-intensity curves (TIC) were compared with hemodynamic flow parameters (resistive index: RI) in patients with good early graft function (EGF) and acute rejection (AR) or acute tubular necrosis (ATN) as a cause of delayed graft function (DGF).

MATERIAL/METHODS

US-CE was conducted in order to assess graft perfusion in the early period after kidney transplantation (72-120 hours) in 63 kidney allograft recipients: 35 with EGF and 28 with DGF. The DGF patients were later diagnosed based on graft biopsy as AR (n = 10) or ATN (n = 18). Time-intensity curves were compared with hemodynamic flow parameters typically assessed in post-operative graft diagnostics (e.g., RI).

RESULTS

In the examination with US-CE in EGF patients, the regular inflow of contrast medium was demonstrated in all regions of the graft. In patients with DGF, a delay in the inflow of the contrast medium was observed, as well as significant differences in the time of inflow to the regions of interest between those 2 groups. There was a significantly longer inflow time of the contrast medium to the cortex and renal pyramids in patients with AR than in ATN recipients.

CONCLUSIONS

US-CE may be a valuable diagnostic tool in the determination of the cause of DGF.

[The usefulness of ultrasonography and Doppler ultrasound in renal transplantation]

OBJECTIVES

The aim of the study is to analyze the usefulness of ultrasound and Doppler ultrasound for the evaluation of transplant donors and recipients, for renal transplant follow-up and for the resolution of surgical complications after renal transplant.

METHODS

Abdominal ultrasound was performed in donors and recipients of renal grafts. In the recipients with vascular risk factors a Doppler ultrasound of the iliac and lower limb arteries was systematically done. Doppler ultrasound was performed in the first and seventh day after renal transplant, as well as for graft dysfunction at any moment.

RESULTS

Recipient ultrasound informs about the existence of acquired renal cystic disease and Doppler ultrasound allows evaluating the vascular state of high risk recipients. In the immediate post-transplant period ultrasound studies are useful for detection of vascular complications, graft obstruction and to control the evolution of acute rejection and acute tubular necrosis. Finally, ultrasound is the technique of choice in the endourological management of surgical complications after renal transplant.

CONCLUSION

Ultrasound under urologic control is essential in the evaluation of the kidney transplant recipient, post-transplant follow-up and in the resolution of surgical complications.

The Myocardial Performance Index detects chronic cardiac allograft dysfunction sooner than other methods

AIM

Many noninvasive techniques have been proposed for the early detection of chronic heart graft dysfunction. Diastolic dysfunction may precede systolic dysfunction, and often is prominent; therefore, the aim of the study was to investigate the clinical and prognostic value of a Doppler-derived index of both systolic and diastolic function in heart transplanted patients (Myocardial Performance Index, MPI).

METHODS

The MPI was measured in 63 consecutive patients (mean age 55 years, 49 men and 14 women) in sinus rhythm with an orthotopic heart transplantation for at least 1 year (mean 5.3 years) and in 63 age and sex-matched controls. A complete clinical examination was performed at the time of enrollment and was repeated after 3 months.

RESULTS

At 3 months, 11 patients (17.5%) presented events (heart failure, hospitalisation or cardiac death). Patients were divided into 2 groups: Group A (52 patients) without events in the follow-up and Group B (11 patients) with events. The values of MPI in Group B (0.55+/-0.19) were significantly higher than values in Group A (0.34+/-0.18, P=0.001). Whereas the values of the index did not differ significantly between Group A and control group (0.34+/-0.18 vs 0.33+/-0.10, P=NS). In the univariate analysis, the population of heart transplanted patients was dichotomised in subgroups by a cut-off MPI of 0.47 and a cut-off ejection fraction (EF) of 50%. Nine patients (41%) with MPI=or>0.47 presented events, while only 2 patients (5%) with MPI<0.47 had any event (P<0.001; c2 12.9). Six patients (85%) with EF<50% had events, while only 5 patients (9%) with EF=or>50% had an event (P<0.001; c2 14). In the multivariate analysis only MPI (chi squared=22.6, P=0.018) and EF (chi squared=20.8, P=0.025) were significant independent predictors of heart failure or cardiac death. By looking at Kaplan-Meyer curves, MPI seems to be better than EF in the earlier detection of graft dysfunction.

CONCLUSION

MPI, as a combined systolic and diastolic index, may detect graft dysfunction earlier than EF.