Intraoperative Perfusion Strategies during Heart Transplantation: Are We Optimizing Renal Protection?

Purpose Acute kidney injury (AKI) is a an important complication following heart transplant (HTX). In this study, we evaluated incidence of AKI after HTX and whether nadir hemoglobin (Hgb), nadir oxygen delivery (DO2) and average DO2 on cardiopulmonary bypass (CPB) were risk factors for AKI. Methods A retrospective, single-institution study of 233 adults undergoing HTX between August 2012 and February 2018 was conducted. AKI was defined as serum creatinine increase ≥0.3mg/dL within 48 hours or ≥50% within 7 days according to Kidney Disease: Improving Global Outcome criteria. Perfusion and laboratory data were examined to calculate nadir values. Chi-square for categorical variables and unpaired t-test for continuous variable were used to detect significant differences between those who did and did not develop AKI. Clinically or statistically significant variables were entered into a multivariable logistic regression model. Hosmer-Lemeshow goodness of fit was used to assess model strength. Results There were no significant differences in age, gender, race, baseline creatinine or baseline GFR between those who did and did not develop AKI (See Table 1). Overall 30-day and 60-day mortality were 2.6% (6/233) and 3.4% (8/233), respectively. Nadir DO2 and average DO2 were significantly different between those with and without AKI (218.86 ml/m2 versus 232.21 ml/m2, p=0.04, and 267.20 ml/m2 versus 281.36 ml/m2, p=0.01, respectively) while nadir Hgb approached significance (8.10 g/dl versus 8.46 g/dl, p=0.057). On multiple regression analysis, higher average DO2 decreased AKI risk (OR 0.991, CI95%=0.983-0.999, and OR 0.987, CI95%=0.975-1.000, respectively). Conclusion This is the largest modern study to examine the relationship between intraoperative perfusion strategy and post op AKI in HTX. Higher oxygen deliver on CPB is associated with a decrease in AKI.