Association Between Intra‐Aortic Balloon Pump Support and Whole Blood Viscosity Following Cardiopulmonary Bypass

ABSTRACT Background The present study aimed to evaluate the association between intra‐aortic balloon pump (IABP) support and whole blood viscosity (WBV) following cardiopulmonary bypass (CPB). Methods In this prospective observational study, 80 patients undergoing CPB were included. Of these, 40 patients received perioperative IABP support, while 40 patients served as the control group. Whole blood viscosity was measured preoperatively and postoperatively across a range of shear rates (0.6–60 s −1 ). Postoperative viscosity values and changes in viscosity (ΔWBV) were compared between groups. Multivariable linear regression analysis was performed to assess the independent association between IABP use and postoperative WBV, adjusting for key clinical variables. Results A decrease in whole blood viscosity was observed after CPB in both groups. Postoperative viscosity values were significantly lower in the IABP group at lower shear rates (0.6 s −1 : 5.35 ± 1.19 vs. 6.71 ± 1.96, p < 0.001; 0.8 s −1 : 4.77 ± 1.07 vs. 5.64 ± 1.52, p < 0.001; 1 s −1 : 4.08 ± 0.93 vs. 5.05 ± 1.22, p < 0.001). In multivariable analysis, IABP use remained independently associated with lower WBV at both 0.6 s −1 ( β = −1.58, p = 0.007) and 1 s −1 ( β = −0.94, p = 0.016). No consistent differences were observed at higher shear rates. Conclusions IABP support is independently associated with reduced whole blood viscosity at lower shear conditions following CPB. These findings may reflect alterations in hemorheological behavior and may have implications for microcirculatory flow and tissue perfusion.