Perioperative Monitoring of Primary and Secondary Hemostasis in Coronary Artery Bypass Grafting

Abstract

On-pump cardiac surgery is accompanied by complex alterations of hemostasis. The excessive postoperative bleeding has been attributed to acquired platelet dysfunction, impaired plasmatic coagulation, and increased fibrinolysis. The characterization of the hemostatic defects responsible for bleeding is crucial for specific treatment and optimal clinical management of the patient. For rapid determination of platelet-dependent primary hemostatic capacity (PHC), the Platelet Function Analyzer PFA-100 system is available. To evaluate the PFA performance in perioperative monitoring, a study was performed in 49 patients selected for low bleeding risk undergoing selective primary coronary artery bypass grafting (CABG). We compared PHC with Simplate bleeding time (BT) and platelet aggregometry. Furthermore, we analyzed global hemostasis by thromboelastography (TEG) and plasmatic coagulation by standard clotting tests prothrombin time (PT, Quick), activated partial thromboplastin time (aPTT), thrombin time (TT) and clotting factors and fibrinolysis by batroxobin (reptilase) time (RT). In all patients BT was postoperatively increased by 1.5- to 2-fold irrespective of perioperative complications and decreased to mildly prolonged values on the first postoperative day (1st day). In patients without complications, PHC in both collagen-adenosine diphosphate closure time (CADP-CT: 83 seconds preop, 78 seconds postop, and 74 seconds 1st day) and collagen-epinephrine closure time (CEPI-CT: 98 seconds preop, 95 seconds postop, 85 seconds 1st day) remained nearly stable. Apart from a patient with postoperative moderate thrombocytopenia, in bleeding patients no other significant defect of postoperative platelet hemostatic capacity was observed. However, on 1st day, the PHC of those patients was significantly reduced compared with non-bleeding patients. In patients with postoperative myocardial ischemia, increased PHC was identified by significantly shorter postoperative CADP-CT (66 seconds vs. 83 seconds) than in uncomplicated patients. By aggregometry, partial platelet dysfunction was observed in some patients without correlation to bleeding complications. In seven of 9 patients the postoperative bleeding complication was attributed to prolonged heparin anticoagulation and/or mildly enhanced fibrinogenolysis/fibrinolysis by TEG and standard plasmatic coagulation tests (TEG: k time 18 minutes vs. 8 minutes; aPTT: 47 seconds vs. 32 seconds; TT: 18.0 seconds vs. 12.3 seconds) and (RT: 19.5 seconds vs. 17.7 seconds). The impairment of PHC, platelet aggregation, and clotting factors observed on the 1st day in bleeding and in intra-aortic balloon pump (IABP) patients are most likely secondary effects, for example, loss of active platelets and clotting factors, to the primary postoperative bleeding or implantation of the IABP. In conclusion, our data indicate that in standard CABG procedures highly variable alterations of the hemostatic system occur after cardiopulmonary bypass (CPB) even in patients with assumed low operative risks. For id...

Perioperative Coagulation Management and Control of Platelet Transfusion by Point-of-Care Platelet Function Analysis

“…Recent studies have shown that, compared to conventional coagulation management, TEG/ ROTEM-based POC coagulation management enables reduction of transfusion requirements and costs in cardiac and liver surgery [7,30,33,34,127,128]. Furthermore, TEG/ROTEM may be helpful to identify patients with elevated risk of postoperative thrombotic complications including myocardial infarction [78,129]. However, it must be considered that impaired primary haemostasis because of von Willebrand syndrome or the effect of antiplatelet drugs -like ASA or clopidogrel -cannot be detected by ROTEM analysis.…”

“…Cho et al [119] demonstrated in their study that residual heparin effects can be detected more sensitively by TEG/heparinase-TEG than by activated clotting time (ACT) / heparinase-ACT. Furthermore, the use of heparinase enables monitoring of haemostasis even in completely heparinised patients during cardiopulmonary bypass [78,110,118,120,121]. As the ROTEM system allows measurement at a large temperature range (30-40 °C), the effects of hypo-and hyperthermia on the coagulation system can be verified [22,122].…”

“…Therefore, PFA-100 results are not easy to interpret during surgery. The predictive value of PFA-100 for postoperative blood loss in routine cardiac surgery is low, but postoperative shortening of CT values may be helpful to identify patients with hyperreactivity of platelets associated with the risk of myocardial lesion and ischaemia [74,[76][77][78]. Whereas ASA resistance detected by Born aggregometry (incidence 5.5%) in a study conducted by Gum et al [79] resulted in a three-fold increase in major adverse events (death, myocardial infarction, or cerebrovascular accident) within 2 years of ASA therapy in cardiovascular patients, in the same study population ASA resistance detected by PFA-100 (incidence 9.5%) was not associated with an increase in major adverse events [80].…”

A comparison of low vs conventional‐dose heparin for minimal cardiopulmonary bypass in coronary artery bypass grafting surgery

“…The heparin required for anticoagulation during CPB must be reversed by an equivalent dose of protamine [11][12][13]. The interplay of inflammation and coagulation cascades has led many clinicians to argue in favour of a high-dose heparin regimen during conventional CPB [14,15].…”

Combined Application of Tranexamic Acid and Thrombelastography in Pediatric Epilepsy Surgery

“…The viscoelastic changes are recorded and finally converted to a curve. It may help doctors evaluate coagulation fuction to decrease the risk for bleeding and reduce the allogeneic blood transfusion in cardiac surgery with cardiopulmonary bypass and in liver surgery (6,(22)(23)(24). TXA reversibly blocks the lysine binding sites of plasminogen, prevents activation of plasmin and stops lysis of polymerized fibrin.…”