Doppler ultrasonographic evaluation of the early changes in renal resistive index in cirrhotic patients undergoing liver transplantation.

Abstract

Renal vasoconstriction commonly occurs in decompensated liver cirrhosis and is entirely reversible after hepatic transplantation. In this study we evaluated by Doppler ultrasonography the changes of renal vascular resistance occurring during the first month after transplantation. In 16 cirrhotic patients the intrarenal resistive index at the level of interlobar arteries and the blood urea nitrogen and serum creatinine levels were measured before (range, 1 to 34 days) and after transplantation (days 1, 3, 7, 14, 30). Before transplantation the median resistive index value was 0.69 (95% CI, 0.65 to 0.71) and eight of 16 patients showed abnormal values (0.70 or more). After transplantation, the median resistive index was significantly decreased on all the evaluation days, and no patient had abnormal values on posttransplantation day 7. No significant correlation was found between resistive index and serum creatinine or blood urea nitrogen levels. Doppler ultrasonography is a simple tool to evaluate the recovery of normal intrarenal arterial resistance levels after liver transplantation. One week appears to be the optimal timing to evaluate the renal resistive index in the posttransplantation period.

Intrarenal resistance index for the assessment of acute renal injury in a rat liver transplantation model

“…Colour coded duplex sonography is the accepted method to assess kidney perfusion after transplantation [12,17,24,26]. A widely used Doppler parameter is the intrarenal RI.…”

“…Although the precise cause of the renal injury after LT remains elusive and is likely multifactor [2,5,7-9], renal vascular tone is one of the factors closely related to the effective renal perfusion and subsequent renal function [10-12]. In many cases, such as hemorrhagic shock, immediate elevations in renal RI have been reported and renal injury may occur as a functional disorder secondary to splanchnic pooling of blood, reduced effective arterial volume and compensatory activation of vasopressor systems leading to increased renal vascular tone [13].…”

“…The pathophysiology of human liver transplantation was more complex than hemorrhage shock, and there would be acute changes in intraoperative hemodynamics resulting from suprarenal inferior vena cava (IVC) occlusion, secondary to ischemia-reperfusion injury in the liver in the procedure [3,6], and would induce major changes in renal vascular tone. However, limited data related to renal vascular tone and renal function directly after reperfusion existed during LT [11,12]. …”

“…The Doppler waveform analysis of the kidneys, semiquantified as the RI, has accumulated for both acute and chronic renal diseases [11,12,14,15]. It has also been thought to indirectly reflect the degree of resistance in the intrarenal vasculature [16] and is gaining growing attention as an important factor predicting the occurrence of AKI in critical care patients [14,17].…”

The role of ultrasonography in the study of medical nephropathy

“…Evaluation of intraparenchymal RI values can provide early signals of nephropathy and/or predict impaired renal function before alteration of clinical-biochemical values in a number of pathologies, such as hemolyticeuremic syndrome [36], ATN [31], and hepaticerenal syndrome [37]. Repeated evaluations are obviously required in order to achieve early detection of possible variations in RI values.…”