Intraoperative Oxygen Delivery and Acute Kidney Injury after Liver Transplantation

Abstract

Although intraoperative hemodynamic variables were reported to be associated with acute kidney injury (AKI) after liver transplantation, the time-dependent association between intraoperative oxygen delivery and AKI has not yet been evaluated. We reviewed 676 cases of liver transplantation. Oxygen delivery index (DO₂I) was calculated at least ten times during surgery. AKI was defined according to the Kidney Disease Improving Global Outcomes criteria. The area under the curve (AUC) was calculated as below a DO₂I of 300 (AUC < 300), 400 and 500 mL/min/m² threshold. Also, the cumulative time below a DO₂I of 300 (Time < 300), 400, and 500 mL/min/m² were calculated. Multivariable logistic regression analysis was performed to evaluate whether AUC < 300 or time < 300 was independently associated with the risk of AKI. As a sensitivity analysis, propensity score matching analysis was performed between the two intraoperative mean DO₂I groups using a cutoff of 500 ml/min/m², and the incidence of AKI was compared between the groups. Multivariable analysis showed that AUC < 300 or time < 300 was an independent predictor of AKI (AUC < 300: odds ratio [OR] = 1.10, 95% confidence interval [CI] 1.06-1.13, time < 300: OR = 1.10, 95% CI 1.08-1.14). Propensity score matching yielded 192 pairs of low and high mean DO₂I groups. The incidence of overall and stage 2 or 3 AKI was significantly higher in the lower DO₂I group compared to the higher group (overall AKI: lower group, n = 64 (33.3%) vs. higher group, n = 106 (55.2%), P < 0.001). In conclusion, there was a significant time-dependent association between the intraoperative poor oxygen delivery <300 mL/min/m² and the risk of AKI after liver transplantation. The intraoperative optimization of oxygen delivery may mitigate the risk of AKI.

Keywords: acute kidney injury; liver transplantation; oxygen content; oxygen delivery.

Figure 1

Comparison of oxygen delivery index (upper), cardiac index (middle) and arterial oxygen content (lower) during liver transplantation between the patients with and without acute kidney injury. The time points compared were as follows: anesthesia induction (T1), 1 h after anesthesia induction (T2), 30 min (T3) and 1 h (T4) after the beginning of the anhepatic phase, 5 min before (T5) and after (T6) graft reperfusion, 20 min after reperfusion (T7), 40 min after reperfusion (T8), 5 min after the completion of biliary reconstruction(T9), and at the end of surgery (T10). * Significant difference between groups.

Figure 2

The cubic spline function curves of the multivariable-adjusted relationship between the area under the threshold of oxygen delivery index (DO₂I) of 300 mL/min/m² (AUC < 300) (upper left) or the cumulative time below the threshold of DO₂I of 300 mL/min/m² (time < 300) (upper right) or mean DO₂I during surgery (lower left), or nadir DO₂I during surgery (lower right) as continuous variables and the risk of acute kidney injury after liver transplantation.