July 10, 2024
Bundling preoperative and postoperative administration of erythropoietin (EPO) with intravenous iron supplementation and restrictive transfusion adjusted for central venous oxygen saturation (ScvO2) significantly reduced the need for red blood cell (RBC) transfusion in patients undergoing cardiac surgery and considered to be at high risk of perioperative transfusion, new research suggests.
The combination of interventions led to a roughly 50% reduction in the number of patients needing RBC transfusions from ICU admission to study discharge. In the intervention group, 14.5% of patients required RBC transfusions, compared to 31.2% in the control group, which received standard patient blood management (PBM) care. The findings, published in The Lancet Regional Health, are based on a single-center randomized open-label pilot study of 123 patients.
The median length of follow up to transfusion was reduced for patients in the intervention group compared with those who received standard PBM care — 2.6 versus 3.3 days, respectively, for the control and intervention groups. Long-term risk of anemia was also reduced for patients in the intervention group —30.4% versus 90.24%, respectively, in the first 3 months after hospital discharge.
With an aging population more likely to have chronic diseases, the prevalence of preoperative anemia is increasing and is estimated to affect 20-40% of patients undergoing cardiac surgery. Both preoperative anemia and perioperative RBC transfusion are associated with poorer outcomes following surgery.
Treatment of preoperative anemia with iron and EPO has been shown to reduce mortality following surgery. While lower hemoglobin-based transfusion thresholds are recommended as part of a PBM program, this can translate to persistent postoperative anemia.
The researchers proposed modifying hemoglobin (Hb) transfusion triggers by using ScvO2 to individualize RBC transfusion. ScvO2 is a metabolic marker of anemia tolerance. Two recent studies demonstrated significant reductions in transfusion exposure.[1],[2]
The study included adults scheduled for elective on-pump cardiac surgery with high risk of transfusion defined by needs by the Transfusion Risk Understanding Scoring Tool (TRUST), which stratifies cardiac surgery patients according to their blood transfusion risk. Patients with a TRUST score of 3 or greater (out of a possible 8) were randomized to ultrashort preoperative anemia treatment with intravenous administration of 20 mg/kg ferric carboxymaltose (FCM) and subcutaneous EPO α.
Anemia was initially defined as Hb less than 12 g/dL, though the threshold was later increased to less than 13 g/dL. Iron deficiency was defined as a ferritin plasma concentration of less than 100 μg/L or a transferrin saturation coefficient (TSC) greater than 20%.
Hb levels were monitored before, during, and after surgery. Patients in the intervention group were transfused postoperatively based on the combination of Hb level and ScvO2. An Hb of 8 g/dL or less and ScvO2 no more than 65% triggered transfusion of one RBC unit. Transfusion was repeated if Hb concentration dropped below 8 g/dL and ScvO2 was no more than 65%. Patients were also transfused if ScvO2 was greater than 65% but Hb was less than 7 g/dL. While patients with Hb greater than 8 g/dL ScvO2 more than 65% were not transfused, they could receive EPO and FCM.
The average age of the patients was 70 years, with an average TRUST score of 3.7. The average preoperative Hb level was 12.9 g/dL. Preoperative anemia was present in 48% (30 out of 62) of patients in the intervention group and 57% (35 out of 61) of patients in the control group.
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