Role of sonographic hepatorenal index and renal resistive index in monitoring of acute kidney injury after liver transplantation.

Background: Acute kidney injury (AKI) is a frequent complication after liver transplantation (LT). How to realize the early diagnosis of AKI, perform active intervention, and reduce the mortality of post-LT patients is an urgent problem to be solved.

Aim: To investigate the accuracy of hepatorenal index (HRI) and renal resistive index (RRI) in monitoring of early AKI after LT.

Methods: This observational study included adult deceased-donor LT recipients at our center between February 2022 and February 2023 with no preoperative renal dysfunction. The HRI and RRI were recorded once per day in the postoperative period through to postoperative day (POD) 7. We followed up with the patients at 1 month after LT. The patients were divided into the AKI and non-AKI groups according to the Kidney Disease Improving Global Outcomes criteria.

Results: Of 121 patients were included in the study (mean age: 50.18 ± 8.88years; female: 17.36%). AKI developed in 53 patients (43.80%). The AKI and non-AKI groups were similar in terms of their baseline characteristics. An HRI of ≤ 1.12 on POD 1 detected AKI with a sensitivity of 62.30% and a specificity of 87.80% [area under the receiver operating characteristic curve (AUC) = 0.801, P < 0.01]. An RRI of ≥ 0.65 on POD 1 detected AKI with a sensitivity of 87.80% and a specificity of 67.60% (AUC = 0.825, P < 0.01). The HRI combined with the RRI was more effective at detecting AKI than either the HRI or RRI alone (AUC = 0.890, P < 0.01). The HRI increased as AKI resolved while the RRI decreased as AKI resolved.

Conclusion: The HRI and RRI are non-invasive bedside indices that can identify the occurrence and recovery of early AKI after LT.