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 conducted a prospective study to assess platelet function, coagulation, and fibrinolysis status during and after infrarenal aortic surgery.
METHODS: Seventeen patients were studied. Excluded were patients with preoperative coagulopathies or liver disease, or cardiac or renal insufficiency; patients receiving anticoagulant treatment, antiplatelet agents, nonsteroidal antiinflammatory agents, fresh frozen plasma, or platelet concentrates; and patients undergoing reoperation and septic patients. Blood samples were drawn before induction (T1), 1 h after incision (T2), 1 h after extubation (T3), 24 h postoperatively (T4), 48 h postoperatively (T5), and at day 7 (T6). The following tests were performed: platelet count, platelet aggregation, platelet flow cytometry for CD62 and CD63, usual coagulation tests, thrombin--antithrombin complexes, plasminogen activator inhibitor 1.
RESULTS: A significant increase of adenosine diphosphate--induced platelet aggregation was observed postoperatively at T4 and T5. This was not associated with a change of flow cytometry profile. No increase of thrombin--antithrombin complex levels was observed. A higher fibrinogen rate was detected at T5 and T6. Greater amounts of plasminogen activator inhibitor 1 were detected at T3 and T4. Thus, thrombin generation was limited and fibrinolysis was impaired postoperatively. Platelets were not activated in the postoperative period, as shown by flow cytometry, but were prone to be activated, as shown by aggregation studies.
CONCLUSION: The association of more easily activated platelets with a higher fibrinogen rate and a temporary shut down of fibrinolysis during the early postoperative period may indicate an increased thrombotic risk in patients undergoing major vascular surgery.