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.

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.

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).

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.