The association between intraoperative cell salvage and red blood cell transfusion in cardiac surgery - an observational study in a patient blood management centre

Abstract

Introduction: Cell salvage (CS) is an integral part of patient blood management (PBM) and aims to reduce allogeneic red blood cell (RBC) transfusion.

Material and methods: This observational study analysed patients scheduled for elective cardiac surgery requiring cardiopulmonary bypass (CPB) between November 2015 and October 2018. Patients were divided into a CS group (patients receiving CS) and a control group (no CS). Primary endpoints were the number of patients exposed to allogeneic RBC transfusions and the number of RBC units transfused per patient.

Results: A total of 704 patients undergoing cardiac surgery were analysed, of whom 338 underwent surgery with CS (CS group) and 366 were without CS (control group). Intraoperatively, 152 patients (45%) were exposed to allogeneic RBC transfusions in the CS group and 93 patients (25%) in the control group (P < 0.001). Considering the amount of intraoperative blood loss, regression analysis revealed a significant association between blood loss and increased use of RBC units in patients of the control compared to the CS group (1000 mL: 1.0 vs. 0.6 RBC units; 2000 mL: 2.2 vs. 1.1 RBC units; 3000 mL: 3.4 vs. 1.6 RBC units). Thus, CS was significantly associated with a reduced number of allogeneic RBCs by 40% for 1000 mL, 49% for 2000 mL, and 52% for 3000 mL of blood loss compared to patients without CS.

Conclusions: Cell salvage was significantly associated with a reduced number of allogeneic RBC transfusions. It supports the beneficial effect of CS in cardiac surgical patients as an individual measure in a comprehensive PBM program.

Keywords: cardiac surgery; patient blood management; transfusion.; cell salvage.

FIGURE 1

Flow chart of the patients included for analysis

FIGURE 2

Regression analysis of intraoperative blood loss and red blood cell (RBC) units transfused. Scatter plot to evaluate the correlation between the amount of blood loss and number of intraoperative transfused allogeneic RBC units. Values are shown for individual patients of the cell salvage (CS) group (red) and control group (black). Results of linear regression analysis are displayed with 95% confidence interval for both groups (dotted line). The difference between the slopes is significant (P = 0.0002). The regression coefficient provides information about the strength and direction of a relationship, R² – coefficient of determination. R² evaluates the scatter of the data points around the fitted regression line; it indicates the quality of the independent variables (blood loss) and can explain the variance of the dependent variables (RBC units). The R² value is always between 0 (no goodness of fit) and 1 (perfect goodness of fit). Y – RBC units transfused, X – blood loss in mL

FIGURE 3

Regression analysis of intraoperative blood loss and red blood cell (RBC) units transfused with adjusted data. Scatter plot to evaluate the correlation between the amount of blood loss and number of intraoperative transfused allogeneic RBC units. Patients’ data after propensity score matching was used. Values are shown for individual patients of the cell salvage (CS) group (red) and control group (black). Results of linear regression analysis are displayed with 95% confidence interval for both groups (dotted line). The difference between the slopes is significant (P = 0.0004). Regression coefficient provides information about strength and direction of a relationship, R² – coefficient of determination. R² evaluates the scatter of the data points around the fitted regression line; it indicates the quality of the independent variables (blood loss) and can explain the variance of the dependent variables (RBC units). R² value is always between 0 (no goodness of Fit) and –1 (perfect goodness of Fit). Y – RBC units transfused, X – blood loss in mL