title: The effects of thrombocytopenia on the activated coagulation time.
abstract: The activated coagulation (clotting) time (ACT) is widely used to monitor heparin therapy during cardiopulmonary bypass (CPB). Since thrombocytopenia occurs during and for some time after CPB, we considered the possibility that thrombocytopenia may affect the ACT. Blood samples were obtained from 12 healthy volunteers. Thrombocytopenic samples were created by a differential centrifugation technique. Blood samples from five thrombocytopenic patients were also studied. The platelet counts of the control citrated whole blood samples were 254,000 +/- 35,000/microL (mean +/- SD), whereas the platelet counts of the thrombocytopenic citrated samples were 49,000 +/- 8000/microL. There were no significant differences in the ACTs between these two groups (143 +/- 8 vs 145 +/- 9 s, respectively, P = 0.16). There were also no significant differences in the ACTs of the heparinized control samples compared with the ACTs of the heparinized thrombocytopenic samples. The platelet counts of the five thrombocytopenic patients were 43,000, 18,000, 16,000, 8000, and 7000/microL, and the ACTs of the unanticoagulated samples were 162, 240, 191, 210, and 215s, respectively. We conclude that the ACT is not affected by moderate thrombocytopenia and therefore this test may be used in patients who are moderately thrombocytopenic.
authors.affiliation: Department of Anesthesiology, Mount Sinai Medical Center, New York, New York 10029, USA.
authors.forename: T
authors.initials: T
authors.lastname: Ammar
authors.forename: C F
authors.initials: CF
authors.lastname: Fisher
authors.forename: K
authors.initials: K
authors.lastname: Sarier
authors.forename: B S
authors.initials: BS
authors.lastname: Coller
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use; D002315:Cardiopulmonary Bypass; D002498:Centrifugation; D006400:Hematocrit; D006493:Heparin / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use; D006801:Humans; D010314:Partial Thromboplastin Time; D010976:Platelet Count; D011517:Prothrombin Time; D013921:Thrombocytopenia / Q000097:blood / Q000503:physiopathology*; D014914:Whole Blood Coagulation Time
chemical_list: D000925:Anticoagulants; D006493:Heparin