Perioperative activation of hemostasis in vascular surgery patients

Background: Perioperative activation of hemostasis could play an important role in the occurrence of postoperative cardiac events. The authors conduct ed a prospective study to assess platelet function, coagulation, and fibrin olysis status during and after infrarenal aortic surgery. Methods: Seventeen patients were studied. Excluded were patients with preop erative coagulopathies or liver disease, or cardiac or renal insufficiency; patients receiving anticoagulant treatment, antiplatelet agents, nonsteroi dal antiinflammatory agents, fresh frozen plasma, or platelet concentrates; and patients undergoing reoperation and septic patients. Blood samples wer e drawn before induction (T1), 1 h after incision (T2), 1 h after extubatio n (T3), 24 h postoperatively (T4), 48 h postoperatively (T5), and at day 7 (T6). The following tests were performed: platelet count, platelet aggregat ion, platelet flow cytometry for CD62 and CD63, usual coagulation tests, th rombin- antithrombin complexes, plasminogen activator inhibitor 1. Results: A significant increase of adenosine diphosphate-induced platelet a ggregation was observed postoperatively at T4 and T5. This was not associat ed with a change of flow cytometry profile. No increase of thrombin-antithr ombin complex levels was observed. A higher fibrinogen rate was detected at T5 and T6. Greater amounts of plasminogen activator inhibitor 1 were detec ted at T3 and T4. Thus, thrombin generation was limited and fibrinolysis wa s impaired postoperatively. Platelets were not activated in the postoperati ve period, as shown by flow cytometry, but were prone to be activated, as s hown by aggregation studies. Conclusion: The association of more easily activated platelets with a highe r fibrinogen rate and a temporary shut down of fibrinolysis during the earl y postoperative period may indicate an increased thrombotic risk in patient s undergoing major vascular surgery.