Highly positive intraoperative fluid balance during cardiac surgery is associated with adverse outcome

Abstract

Hemodilution and increase in capillary permeability occurring with cardiopulmonary bypass (CPB) impose a risk for tissue edema and blood transfusion that may result in an increased complication rate after coronary artery bypass grafting (CABG). Of the 1280 consecutive patients undergoing isolated on-pump CABG, total fluid balance at the end of the operation was less than or equal to 500 mL in 1155 (Group 1) and more than 500 mL in 125 (Group 2). During CPB, blood was added to the reservoir only when the hematocrit fell to 17% or less and crystalloid solution only when the pump flow index fell below 2.0 L/min/m2. Anesthetic, surgical, and postoperative management and diagnoses were the same in all patients, and a single surgical and anesthesia team performed all operations. No patient was excluded from the study. Results: Hypertension, diabetes, chronic obstructive pulmonary disease, New York Heart Association (NYHA) Class III - IV, use of angiotensin converting enzyme (ACE) inhibitors, chronic renal failure, and female gender were the significant preoperative risk factors for increased volume replacement during CPB. The groups were similar in body mass index, preoperative hematocrit values, total fluid balance in the intensive care unit (ICU), and total chest tube output. However, red blood cells’ transfusion rate, readmission rate to the ICU and length of hospital stay were significantly higher in Group 2 patients. Multiple logistic regression revealed that age < 70 years ( p < 0.001, Odds Ratio (OR): 2, 95% CI: 1.4 - 2.8), and total fluid balance > 500 mL at the end of the operation ( p < 0.01, OR: 2.2, 95% CI: 1.5-3.2) were the predictors of increased length of stay. For transfusion of red blood cells, age > 70 years ( p < 0.0001, OR: 2.3, 95% CI: 1.6-3.3), and total fluid balance > 500 mL at the end of the operation ( p < 0.001, OR: 2, 95% CI: 1.3-2.9) were the only significant risk factors. This study suggests that intraoperative volume overload increases blood transfusion and length of hospital stay in patients undergoing CABG.