Determinants of the serial changes in measurements of renal allograft Doppler resistive index in the first postoperative month

Abstract

Introduction: The role of single Doppler-derived renal resistive index (RI) in renal allograft management is still a controversial issue, however detection of changes in serial duplex scanning has been reported as more valuable. This study aimed to test the hypothesis that early change in RI following transplantation may be related to factors associated with delayed graft function (DGF). Material and methods: 113 patients were included, in whom two RI measurements were performed within 30 days post-transplant. According to an RI change (equal to or more than 10%) in the second measurement, patients were assigned to decrease (Group I), no change (Group II), or increase (Group III) group. Results: 30 subjects had a decrease, 55 had no change, and 28 had an increase in the second RI measurement. The donors were younger in Group III in comparison to Group II. In comparison to Group I, Group III had a higher frequency of deceased donor, DGF, and presence of tubular necrosis and tubular vacuolization in peri-implantation biopsies. Conclusion: the increase of RI during the first weeks of the postoperative period seems to be associated with DGF and with tubular necrosis / tubular vacuolization in peri-implantation biopsies, likely related to ischemia reperfusion injury.

Serial changes in renal allograft resistive index

“…In this issue, Moura-Neto et al 1 evaluated the role of serial RI in the immediate postoperative period to assess delayed graft function due to ischemia-reperfusion injury in 113 renal transplant patients. The study excluded patients with histology-proven acute rejection, hydronephrosis of grade 2 or higher, and peritransplant collections causing marked compression, as these conditions may also cause elevated RIs.…”

“…This is consistent with studies that have shown RI elevation on immediate postoperative Doppler ultrasound as a predictor of acute tubular necrosis (ATN) and delayed graft function 2 , 3 . While most studies evaluate RI on a single early postoperative Doppler ultrasound, Moura-Neto et al 1 incorporated two serial measurements of RI over four weeks and evaluated interval change. This approach of analyzing change over serial studies has been used by other authors and may be more reflective of the allograft characteristics than a single measurement, particularly in the early postoperative period.…”

“…Multiple studies have shown that a normal RI in the immediate post-operative period is a good predictor for immediate graft function. Moura-Neto et al 1 add to this literature by reporting that decreasing RI in the first few post-operative weeks is associated with better serum creatinine and lower likelihood of requiring dialysis.…”