Prospective Observational Study of Flow-Based Platelet Function Using T-TAS and Early Bleeding After Cardiopulmonary Bypass in Adult Cardiac Surgery

Cardiac surgery requiring cardiopulmonary bypass (CPB) is frequently associated with perioperative hemostatic disturbances and clinically significant postoperative bleeding. The mechanisms involved are multifactorial and include platelet activation and dysfunction, hemodilution, inflammatory activation, acquired von Willebrand factor (vWF) abnormalities, fibrinolytic activation, exposure of blood to non-endothelial surfaces, hypothermia, and the effects of systemic anticoagulation and heparin reversal. These alterations contribute to increased transfusion requirements, re-exploration for bleeding, prolonged intensive care unit (ICU) stay, and increased perioperative morbidity.

Conventional coagulation tests incompletely characterize perioperative primary hemostatic dysfunction during cardiac surgery. Standard plasma-based coagulation assays provide limited information regarding platelet thrombus formation under physiologic flow conditions, while platelet aggregometry and viscoelastic testing assess only selected components of the hemostatic process. In addition, several perioperative alterations observed after CPB, particularly abnormalities involving platelet-vWF interactions under shear stress conditions, may not be adequately reflected by conventional laboratory methods.

The Total Thrombus-formation Analysis System (T-TAS) is a microfluidic flow chamber platform that evaluates thrombus formation in whole blood under controlled flow conditions. The Platelet-chip (PL-chip) primarily assesses platelet thrombus formation on collagen-coated microchannels under arterial shear flow conditions, integrating platelet adhesion, activation, aggregation, and vWF-dependent interactions. The AR-chip additionally incorporates activation of the coagulation cascade and fibrin formation. T-TAS therefore provides a functional assessment of thrombus formation under conditions that more closely resemble physiologic blood flow than conventional static coagulation assays or standard aggregometry techniques.

Although T-TAS has been investigated in several thrombotic and bleeding disorders, its perioperative behavior and potential clinical relevance in adult cardiac surgery with CPB remain insufficiently characterized. In particular, the association between post-CPB T-TAS parameters and early postoperative bleeding has not been clearly established, and the relationship between T-TAS and conventional coagulation, viscoelastic, platelet function, and vWF-related laboratory assessments remains incompletely understood in this clinical setting.

This study is a prospective, observational, single-center cohort study conducted at Hospital de la Santa Creu i Sant Pau (Barcelona, Spain). The study is designed to characterize perioperative alterations in flow-based platelet thrombus formation and to evaluate the relationship between T-TAS parameters and early postoperative bleeding after adult cardiac surgery requiring CPB.