Preoperative anemia and nadir hemoglobin (Hb) during cardiopulmonary bypass (CPB) have been identified as significant risk factors for blood transfusion during cardiac surgery. The aim of this study was to confirm the association between preoperative anemia, perioperative fluid management, and blood transfusion. In addition, the proportion of elective cardiac surgery patients presenting for surgery with anemia was identified to examine whether the opportunity exists for timely diagnosis and intervention. Data from referral until hospital discharge were comprehensively reviewed over a 12-month period for all nonemergency cardiac surgical patients operated on in our institution. Of the 342 patients identified, elective cases were referred a median of 35 days before preoperative clinic and operated on a median of 14 days subsequently. Subacute cases had a median of 3 days from referral to surgery. As per the World Health Organization (WHO) criteria for anemia, 24.2% of elective and 29.6% of subacute patients were anemic. Blood transfusion was administered to 46.2% of patients during their admission. Transfusion was more likely in patients who were female (odds ratio [OR]: 2.45, 95%confidence interval [CI]: 1.28-4.70), had a low body mass index (BMI) (OR: .89, 95% CI: .84-.94), preoperative anemia (OR: 5.15, 95% CI: 2.59-10.24), or renal impairment (OR: 5.44, 95% CI: 2.42-12.22). Hemodilution minimization strategies reduced the Hb fall during CPB, but not transfusion rates. This study identifies a high prevalence of preoperative anemia with sufficient time for elective referrals to undergo appropriate diagnosis and interventions. It also confirms that low red cell mass (anemia and low BMI) and renal impairment are predictors of perioperative blood transfusion. Perfusion strategies to reduce hemodilution are effective at minimizing the intraoperative fall in Hb concentration but did not influence transfusion rate.
Keywords: anemia; blood management; cardiac surgery; cardiopulmonary bypass.