Contributing factors to heparin resistance during cardiopulmonary bypass.

Abstract

Since the risk factors for heparin resistance (HR) before cardiopulmonary bypass (CPB) have not been fully clarified, this study investigated the contributing factors for HR after the initial unfractionated heparin (UFH) dose of 500IU/kg. We retrospectively analyzed the data of 371 patients who underwent CPB surgery, with the initial UFH dose of 500IU/kg, between May 2017 and December 2021. We defined HR as the failure to achieve activated clotting time (ACT) of > 480s after the initial UFH dose of 500IU/kg. HR was observed in 36 patients (9.7%) (HR group), while HR was not observed in 335 patients (control group). The HR group included significantly more patients with preoperative use of UFH, with significantly higher white blood cell counts, fibrinogen, fibrinogen degradation products, D-dimer, and C-reactive protein, and lower hemoglobin and albumin. The multivariable logistic regression analysis identified albumin (OR: 3.09, 95% CI 1.3504-7.0845, p = 0.0075) and fibrinogen (OR: 0.99, 95% CI 0.9869-0.9963, p = 0.0003) as independent predictors for HR. Using the Youden index, the cutoffs of albumin and fibrinogen were calculated as 3.8g/dL and 303mg/dL, respectively. The receiver operating characteristic curves showed the predictive performance of albumin (area under the curve (AUC): 0.78, sensitivity: 65%, specificity: 81%) and fibrinogen (AUC: 0.77, sensitivity: 56%, specificity: 88%). The incidence of HR after the initial UFH dose of 500IU/kg was 9.7%. The preoperative albumin < 3.8g/dL and fibrinogen > 303mg/dL were independent predictors for HR.