Renal resistive index as a predictor of acute kidney injury in patients undergoing living donor liver transplantation—a prospective observational study

Abstract

Background

The incidence of acute kidney injury (AKI) following liver transplantation ranges from 40 % to 60 %. Early prediction or diagnosis of AKI could significantly enhance patient outcomes. Our study aimed to determine the role of the Renal Resistive Index (RRI) via ultrasound-Doppler imaging in predicting AKI and identifying other potential factors associated with it.

Methodology

We conducted a single-center, prospective study involving 78 subjects who underwent adult living donor liver transplantation (LDLT) between March 2023 and December 2023. Ultrasound Doppler RRI was measured preoperatively and then daily until postoperative day (POD) 5.

Results

Patients who developed AKI within the first 5 POD showed an increasing RRI on POD1, while others experienced a gradual decline in RRI following LT. In our study, preoperative RRI predicted AKI on POD1 with an area under the curve (AUC) of 0.67 at a cut-off of ≥0.68. Moreover, POD2 RRI predicted AKI on POD3 with a superior AUC of 0.87 at the same cut-off. Given the proximity of the median to the optimal cutoff point, we explored expressing the values as relative renal resistance and calculated the ratio between RRI and the Hepatic artery resistive index, referred to as the RH ratio. Our findings indicate that the POD2 RH ratio predicted AKI on POD3 with an AUC of 0.71 at a cut-off of ≥0.90. The incidence of AKI on POD3 was 41.7 % when the POD2 RRI was ≥0.68 and 27.5 % when the POD2 RH ratio was ≥0.9. When both the RH ratio and RRI exceeded their respective cutoff values on POD2, the incidence of POD3 AKI was 52.9 %.

Conclusion

RRI measurement via Doppler is a noninvasive, simple bedside procedure that can predict AKI in the immediate postoperative period after LDLT.