Acute normovolemic haemodilution to reduce allogeneic red blood cell transfusion in patients undergoing coronary artery bypass grafting. An observational study.

Background and objective: Patients undergoing cardiac surgery consume more than 50% of blood transfusions, and such transfusions have been associated with increased morbidity and mortality. Evidence in blood-saving techniques has increased the use of acute normovolemic haemodilution (ANH) in high-risk settings. The aim was to determine the incidence of allogeneic red blood cell transfusion perioperatively in acute normovolemic haemodilution (ANH) patients undergoing coronary artery bypass grafting (CABG).

Materials and methods: This prospective observational cohort study was conducted in the Cardiac OR and ICU over 6 months, involving elective CABG patients aged 35-70 with ASA status III and IV. Haemoglobin and haematocrit levels were assessed preoperatively, intraoperatively and 24 h postoperatively.

Results: In a cohort of 50 ANH patients, 44% (22/50) required allogeneic blood transfusion perioperatively, with 24% (12/50) intraoperatively, 14% (7/50) in the ICU and 6% (3/50) both intraoperatively and postoperatively. Lower intraoperative haemoglobin levels during CPB were significantly associated with increased transfusion odds in both univariable (OR, 0.25; 95% CI, 0.10-0.49, p = 0.001) and multivariable analyses (Adj. OR, 0.24; 95% CI, 0.09-0.62, p = 0.003), and prolonged surgical duration was a significant predictor in multivariable analysis (Adj. OR, 2.18; 95% CI, 1.01-4.73, p = 0.044). Additionally, prolonged wound healing was significantly more frequent in the patients requiring allogeneic blood transfusions (p = 0.044) highlighting potential postoperative complications.

Conclusion: Our study highlights the varying RBC transfusion rates in CABG patients, with lower intraoperative haemoglobin levels and prolonged surgical duration significantly increasing transfusion needs. These findings emphasise the importance of optimising intraoperative management to minimise transfusions and improve patient outcomes.