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

Abstract

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 (P_rvO₂), may be useful. The aim of this study was to explore the correlation between P_rvO₂ 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 P_rvO₂ 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 (%ΔSCr) and P_rvO₂. A GLM was also performed to determine the association of P_rvO₂ 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). P_rvO₂ was negatively correlated with SCr5 (ρ = -0.53, P = .003), and positively correlated with GFR5 (ρ = 0.49, P = .001) and %ΔSCr (ρ = 0.47, P = .002). A higher P_rvO₂ was associated with an increase in GFR in univariable (β = 1.24, 95% CI, 0.56-1.93, P = .001) and multivariable (β = 1.24, 95% CI, 0.53-1.94, P = .001) analyses. No association was found between P_rvO₂ and SGF.

Conclusion: P_rvO₂ 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.