Shear-Induced Pathway of Platelet Function in Cardiac Surgery

Abstract

The conlribulion of plalelel dysfunclion to Ihe impaired hemostasis afler cardiac surgery remains to be established, because Ihere is no sensilive method to assess platelet funclion. Measurement of the shear-induced pathway of platelet function, an importanl mechanism in inducing hemostasis, became possible by a novel shear-inducing technique, the in-vitro bleeding test (Thrombostat 4000). By using this test, the changes in plalelet function during cardiopulmonary bypass and their conlribulion 10 hemostasis were investigated in patients undergoing cardiac surgery. Platelet function is quickly impaired shortly after Ihe slarl of cardiopulmonary bypass, and partly recovered al Ihe end of cardiopulmonary bypass. The function of aspirin-Ireated platelets is more severely affecled Ihan of nonaspirin platelets during cardiopulmonary bypass. Furthermore, Ihe degree of platelet dysfunclion at Ihe end of Ihe operation, but neither the platelet number nor Ihe activated clotting lime, was significantly correlated with hlood loss from the chest drain after cardiac surgery. These results indicate the significant and variable effects of cardiopulmonary bypass on Ihe shear-induced pathway of platelel function. Moreover, the impairment of Ihis function of platelets appears to be a major cause of excessive bleeding in patients after cardiac surgery. Therefore, Ihe routine use of Ihe shear-inducing lesl seems helpful to make a proper diagnosis and design Ihe Iherapy for bleeders after cardiac surgery.Plalelet dysfunction is considered to be a major cause of excessive bleeding in patients after cardiopulmonary bypass. 1-3 The problem of excessive bleeding becomes larger in cardiac surgery because most patients suffering from coronary artery disease are now treated with aspirin before operation" Despite many investigations on this topic, no useful method has been established to assess platelet dysfunction during and after cardiopulmonary bypass. 5.6 Therefore, no clear evidence has been collected about the contribution of platelet dysfunction to the impaired hemostasis after cardiac surgery. With recent techniques inducing shear-stress, a standard measurement of the shear-induced pathway of platelet function has become possible 7 -J 1 Although the role of the shear-induced pathway remains to be established among other platelet functions, it has to be concluded 12 that the shear-induced pathway of platelet function is an important mechanism of platelet function contributing to hemostasis. In the present study, we hypothesized that the shear-induced pathway of platelet function is a main function of platelets inducing hemostasis, and investigated the change of platelet function during cardiopulmonary bypass and its correlation to the hemostatic status of patients after cardiac surgery. A novel shear-inducing technique, the invitro bleeding test (Thrombostat 4000), was used. PATIENTS AND METHODS Patients and ProtocolPatients undergoing elective, primary coronary artery bypass grafting surgery were selected for the study. 66

A Study of Platelet Activation during Human Cardiopulmonary Bypass and the Effect of S-Nitrosoglutathione

“…The impairment of bleeding time and aggregation predict bleeding complications and are not accounted for by the initial dilutional fall in platelet count (2). Similarly, the impairment of shear-induced platelet activation conelates with blood loss and is independent of the change in platelet count (12).…”

Innate immunity, coagulation and surgery

“…Increased postoperative bleeding after CPB has been attributed to impairment of hemostatic system by for e.g. platelet dysfunction (77), hyperfibrinolysis (78), hemodilution (79) and excessive activation of both the intrinsic and extrinsic pathway by blood contact with extracorporeal surfaces (80)(81). Therefore, it is imperative that during such procedures, hemostasis screening and careful monitoring of blood components and coagulation factors are carried out (82)(83).…”

Gelatin Use Impairs Platelet Adhesion during Cardiac Surgery

“…Platelet plug formation under shear-stress was tested in a shear-inducing device (Thrombostat 4000R, VDG-von der Goltz, Seeon, Germany, and Bax ter Diagnostica AG, Dudingen, Switzerland) (13,14). Briefly, citrated blood…”