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The incidence of heparin resistance in patients operated with the use of extracorporeal circulation
Brzek, Vladimír ; Harrer, Jan (advisor) ; Tošovský, Jan (referee) ; Gwoździewicz, Marek (referee)
Heparin resistance occurs in about 20% of population. In that case, after application of a usual dose of heparin (2-3 mg/kg) ACT will not be sufficiently extended. Aim: To determine the real incidence of heparin resistance in patients scheduled for a cardiac surgical procedure. To determine whether there is an association between preoperative treatment with heparin and the incidence of heparin resistance. Also, to establish whether there is an association between platelet count, patients' age, and heparin resistance. Patients and methods: A total of 624 patients scheduled for on-pump surgery were included into a prospective study over a period of three years. Preoperative and intraoperative activated clotting time (ACT) values were recorded. Additionally, four factors referred to in the relevant literature as potential causes of developing heparin resistance were monitored in all patients: age 65 years, preoperative platelet count ≥ 300 × 109/l, preoperative administration of various types of heparin, antithrombin concentration ≤ 60%, and a combination of all. Patients were considered heparin-resistant if a heparin dose ≥ 5 mg/kg had not produced an anticoagulation response with ACT ≥ 480 s. Our data were evaluated using the test of agreement of relative frequency and the χ2 test. Results: In our...
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