Intraoperative Anemia and Single Red Blood Cell Transfusion During Cardiac Surgery: An Assessment of Postoperative Outcome Including Patients Refusing Blood Transfusion.

OBJECTIVES: Increasing evidence suggests benefits from restrictive red blood cell transfusion (RBC) thresholds in major surgery and critically ill patients. However, these benefits are not obvious in cardiac surgery patients with intraoperative anemia. The authors examined the association between uncorrected hemoglobin (Hb) levels and selected postoperative outcomes as well as the effects of RBCs.

DESIGN: Cohort study with prospectively collected data from a cardiac surgery registry.

SETTING: A major cardiac surgical hospital within the Netherlands, which is also a referral center for Jehovah's Witnesses.

PARTICIPANTS: Patients (23,860) undergoing cardiac surgery between 1997 and 2013.

INTERVENTIONS: Comparisons were done in patients with intraoperative nadir Hb<8 g/dL and/or an Hb decrease ≥ 50%. Comparison (A) between Jehovah's Witnesses (Witnesses) and matched non-Jehovah's Witnesses (non-Witnesses) transfused with 1 unit of RBC, and comparison (B) between patients given 1 unit of RBC intraoperatively versus matched non-transfused patients.

MEASUREMENTS AND MAIN RESULTS: Postoperative outcomes were myocardial infarction, renal replacement therapy, stroke, and death. With propensity matching, the authors optimized exchangeability of the compared groups. Adverse outcomes increased with a decreasing Hb both among Witnesses and among non-Witnesses. The incidence of postoperative complications did not differ between Witnesses and matched non-Witnesses who received RBC (adjusted odds ratio 1.44, 95% confidence interval 0.63-3.29). Similarly, postoperative complications did not differ between patients who received a red cell transfusion and matched patients who did not (adjusted odds ratio 0.94, confidence interval 0.72-1.23).

CONCLUSION: Intraoperative anemia is associated with adverse outcomes after cardiac surgery, and a single RBC transfusion does not seem to influence these outcomes.