Evaluation of The Effect of Acute-normovolemic Hemodilution on Blood Transfusion Rate in Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass: A Prospective Randomized and Controlled Trial : Short title: Acute-normovolemic Hemodilution in CABG.

BACKGROUND: Perioperative use of allogeneic blood products is associated with increased mortality, morbidity, and postcardic therapy. The effectiveness of blood preservation strategies such as acute isovolemic hemodilution (ANH) has been demonstrated with varying degrees of success. This study presents an analysis of the effects of isovolemic hemodilution on blood transfusion in patients undergoing cardiopulmonary bypass.

MATERIAL AND METHODS: We tested the efficacy of ANH in reducing cardiac morbidity during anesthesia prior to cardiopulmonary bypass using a randomized trial. They were divided into two groups: ANH (88 patients) and standard control (88 patients), both selected as CS. The ANH group aimed to achieve a hematocrit level of 28% by performing full blood exchange with colloids. Patients underwent myocardial protection procedures, including cold blood cardioplegia and anesthesia preconditioning. Outcomes were evaluated by measuring cardiac enzymes, including serum troponin I and creatinine phosphokinase. Changes in demand for cardiovascular and cerebrovascular drugs were also taken into account.

RESULTS: Intraoperative fluid balance (crystalloids, colloids, and urine), postoperative fluid balance (crystalloids plus colloids, urine, and chest tube fluid), and RBC concentrate were not statistically different between the two groups (P0.05). However, the results showed that the hematocrit level was more stable in the ANH group than in the control group.

CONCLUSION: Preoperative ANH provides better hematocrit stability and better cardio protection in patients receiving a myocardial perfusion pump; but does not affect water and urine treatment.