Role of Renal Venous Oxygen Pressure for Renal Function Monitoring After Related Living-Donor Kidney Transplantation: Cohort Study

Background. Monitoring of renal function after kidney transplantation (KT) is performed by measuring serum creatinine (SCr), urine volumes (UV), and glomerular filtration rate (GFR). Other methods based on oxygen metabolism, such as the renal venous oxygen pressure (PrvO2), may be useful. The aim of this study was to explore the correlation between PrvO2 and SCr, UV, and GFR 5 days after KT (SCr5, UV5, and GFR5, respectively). Methods. We conducted a prospective cohort study in adults scheduled for living donor KT. A venous blood sample was taken from the renal vein after declamping the renal artery, and blood gas determinations were made. Correlation analyses between PrvO2 and SCr5, UV5, and GFR5 were done by calculating Spearman's correlation coefficient with generalized linear models (GLM). A Spearman's correlation analysis was performed between the percentage decrease in SCr (%DSCr) and PrvO2. A GLM was also performed to determine the association of PrvO2 with slow graft function (SGF). Results. The study included 42 patients, of whom 67% were men. The median age was 31 years (IQR, 27-43.5). PrvO2 was negatively correlated with SCr5 (r = -0.53, P = .003), and positively correlated with GFR5 (r = 0.49, P = .001) and %DSCr (r = 0.47, P = .002). A higher PrvO2 was associated with an increase in GFR in univariable (b = 1.24, 95% CI, 0.56-1.93, P = .001) and multivariable (b = 1.24, 95% CI, 0.53-1.94, P = .001) analyses. No association was found between PrvO2 and SGF. Conclusion. PrvO2 could be used to monitor renal function in the first 5 days after related living -donor KT, given its good correlation with SCr and GFR.