The effect of urinary partial oxygen pressure measurements on the prediction of acute kidney injury (AKİ) in the postoperative period in liver transplant recipients

Objective: In our study, we aimed to investigate the efficacy of urine partial oxygen pressure level measurements in the early recognition of acute kidney injury (AKI), which is frequently encountered in the postoperative period in liver transplant surgery. Materials and Methods: Our prospective, single-center study was conducted at the Inonu University Faculty of Medicine, Turgut Ozal Medical Center Liver Transplant Institute, between August 17, 2023, and March 25, 2024. After excluding patients with fulminant hepatic failure requiring emergency transplantation, hepatic encephalopathy, preoperative hepatorenal or hepatopulmonary syndromes, cadaveric transplants, and those outside the age range of 18–65 years, 99 patients out of a total of 139 liver transplant recipients were included. Urine samples were collected at three time points: surgical initiation (T1), surgical completion (T4), and 24 hours postoperatively (T5). These samples were analyzed using a blood gas analyzer to measure partial oxygen pressure levels. Plasma NGAL levels were also measured 24 hours postoperatively. Patients were categorized into two groups based on the presence or absence of acute kidney injury (AKI), as defined by kidney disease improving global outcomes (KDIGO) diagnostic criteria. Results: Urine partial oxygen pressure (PuO2) values of 99 patients included in the study were compared between the groups and statistical significance was observed only at the postoperative 24th hour (T5) time point, which was higher in Group AKI. There was a significant difference between the groups in FiO2 at the end of the operation (T4) and lactate at the end of the operation. The difference was found to be higher in the ABH group. When NGAL values were analyzed, the mean value of all patients was 124.63±157.5 pg/mL, 64.981(1-608.5) in the control group and 68.39(1-671) in the AKI group and there was no significant difference between the groups (p>0.05). A total of 37 patients developed AKI but no patient developed permanent renal failure. It was observed that the group with AKI was hemodynamically anstable, more acidotic and needed vasopressor support more. Conclusion: In conclusion, we found that noninvasive intermittent PuO2 measurements were inadequate in predicting ABH in our study, but we believe that more prospective studies should be conducted on the subject. Keywords: Liver transplantation, postoperative acute kidney injury (AKI), plasma neutrophil gelatinase-associated lipocalin (NGAL), urinary partial oxygen pressure (PuO₂) , kidney disease improving global outcomes (KDIGO)