Objective: To determine whether bioelectrical impedance-derived phase angle (PA) can be a predictor of red blood cell (RBC) transfusion in patients undergoing cardiac surgery.
Design: An observational retrospective study of prospectively collected data.
Setting: Single center, tertiary referral university hospital.
Participants: The study sample comprised 642 adult patients undergoing elective cardiac surgery.
Interventions: Patient demographic and clinical variables were collected. The body composition of the patients was evaluated by bioelectrical impedance analysis (BIA) the day prior to surgery. The rates of postoperative RBC transfusion were recorded.
Measurements and main results: Among the 642 patients (67.8% men, median age of 66 [range 59-73]) included in the present study, 210 (32.7%) received at least 1 RBC unit postoperatively. Hypertension, preoperative stroke, renal failure, preoperative hemoglobin and hematocrit values, BIA-derived PA, aortic crossclamp time, and cardiopulmonary bypass (CPB) time were associated with the risk of RBC transfusion in the univariate analysis, and were included in the final multivariate regression model. Preoperative stroke (odds ratio [OR] 0.394; 95% confidence interval [CI]: 0.183-0.848; p = 0.017), preoperative hemoglobin values (OR 0.943; 95% CI: 0.928-0.960; p < 0.001), PA <15th percentile (OR 2.326; 95% CI: 1.351-4.000; p = 0.002), and CPB time (OR 1.013; 95% CI: 1.008-1.018; p < 0.001) were identified as independent predictors of RBC transfusion.
Conclusion: Several factors were identified to be associated significantly with postoperative RBC transfusion in patients undergoing cardiac surgery. Among the conventional predictors, the value of the BIA-derived PA was indicated as a potent prognostic tool.
Keywords: bioelectrical impedance analysis; cardiac surgery; phase angle; red blood cell transfusion.
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