A GDP strategy is effective in reducing AKIN stage 1 AKI. Further studies are needed to define perfusion interventions that may reduce more severe levels of renal injury (AKIN stage 2 or 3).

Introduction: Patients refusing blood products in cardiac surgery present challenges for cardiopulmonary bypass. Accurate detail of the modifiable factors of cardiopulmonary bypass relating to acute kidney injury is previously unreported in this patient population. Methods: A total of 118 adult Jehovah’s Witness patients refusing transfusion were propensity matched to 118 adult patients accepting transfusion from the 30,942 patients in the Australian and New Zealand Collaborative Perfusion Registry. The primary endpoint was acute kidney injury. Intraoperative and bypass management characteristics were also compared between early (2007-2012) and late (2013-2018) cohorts along with the acceptance or refusal of transfusion. Results: In patients accepting transfusion, 49% received a blood product. In patients refusing transfusion, acute kidney injury was lower (8% vs. 22%; p = 0.003) cell salvage use was higher (70% vs. 22%; p < 0.001), as was use of haemofiltration (8% vs. 4%; p = 0.03) and tranexamic acid in the early period (87% vs. 62%, p = 0.004) but not late (100% vs. 97%; p = 0.15). There was no difference in modifiable cardiopulmonary bypass factors (mean arterial pressure, minimum oxygen delivery (DO2i), retrograde autologous prime, circuit prime volume) between the two groups; however, prime volume decreased and DO2i increased over time for both. Patients refusing transfusion had lower postoperative blood loss (p = 0.02) and shorter postoperative length of stay (p < 0.001) with no difference in morbidity (p = 0.46) or mortality (p = 0.68). Conclusion: Refusal of transfusion in patients undergoing cardiopulmonary bypass was associated with reduced acute kidney injury, hospital stay and postoperative blood loss, while not impacting mortality.

Acute kidney injury (AKI) following cardiopulmonary bypass (CPB) is associated with increased mortality, requirement for dialysis, and longer intensive care unit (ICU) and hospital length of stay. Rewarming during CPB and poor oxygen delivery have been associated with AKI; however, the role of temperature management on AKI has not been clearly defined. This study aims to evaluate the role of hyperthermia during CPB and the temperature upon admission to the ICU on AKI following cardiac surgery, using the RIFLE (renal Risk, Injury, Failure, Loss of renal function and End-stage renal disease) criteria. To determine whether CPB hyperthermia (measured as the cumulative time the arterial outlet temperature >37°C) and ICU admission temperature were independent risk factors for AKI, data from 1393 consecutive adult patients undergoing isolated on-pump coronary artery bypass graft (CABG), valve repair and/or replacement and valve/CABG procedures was analysed using a logistic multivariate model. After testing for interaction, we incorporated covariates having a p-value <0.1. AKI was defined according to the RIFLE criteria as an increase in serum creatinine >50% from baseline to peak value postoperatively. Overall, 12.3% of patients developed AKI with a 4.5-fold increase in in-hospital mortality. Variables found to be independent predictors of AKI included CPB hyperthermia (Odds ratio [OR] 1.03 per minute increase [95% confidence interval (CI) 1.01-1.05]; p = 0.01), ICU admission temperature ([OR] 1.44 per degree increase [(CI) 1.13-1.85]; p<0.001), minimum CPB haemoglobin ([OR] 0.83 per g/dL increase [(CI) 0.71-0.97]; p = 0.02), use of intra-aortic balloon pump ([OR] 2.69 [(CI) 1.24-5.82]; p = 0.01) and ICU readmission ([OR] 3.13 [(CI) 1.73-5.64]; p<0.001). Avoiding arterial outlet hyperthermia may help decrease AKI following cardiac surgery using CPB. Both intraoperative and postoperative temperature management strategies should be the focus of future randomised studies to determine optimal interventions.