The impact of body mass index on intraoperative and postoperative blood transfusion amounts in coronary artery bypass surgery

Aims: The relationship between obesity, bleeding volume, and transfusion requirements during and after coronary artery bypass surgery remains unclear. This study aimed to investigate the impact of body mass index (BMI) on the amount of intraoperative and postoperative blood transfusions in patients undergoing coronary artery bypass grafting (CABG). Methods: This retrospective study included 288 patients who underwent isolated cardiopulmonary bypass for CABG between 2011 and 2017. Patients were stratified into five BMI categories: underweight (<18.5 kg/m²), normal weight (18.5–24.9 kg/m²), overweight (25.0–29.9 kg/m²), and obese (30.0 kg /m2 <= BMI < 35.0 kg/m2), and morbid obese (BMI >= 35.0 kg/m2). Demographic data, pump times, cross-clamp times, and the amounts of intraoperative and postoperative blood transfusions were retrospectively collected. Results: Among the patients, obese and morbidly obese individuals comprised 38.2% of the cohort, while underweight patients accounted for only 1.0%. The number of bypassed vessels and mean cross-clamp times did not significantly differ between the BMI groups. The mean amount of blood transfused during surgery ranged from 1.66 to 3.43 units, with the highest amounts observed in the morbidly obese group. However, no significant differences were found in the amount of blood transfused postoperatively between the BMI groups. Conclusion: Patients at the extremes of the BMI spectrum, specifically morbidly obese individuals, required higher amounts of blood transfusions intraoperatively compared to other groups. In contrast, postoperative transfusion amounts were comparable across all BMI categories. These findings underscore the importance of tailoring perioperative management strategies based on BMI levels to optimize patient outcomes.