Articles: prothrombin-time.
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The Nurse practitioner · Sep 1995
Review Case ReportsInternational Normalized Ratio (INR): an improved way to monitor oral anticoagulant therapy.
Oral anticoagulant therapy may be inappropriately managed and thus potentially place the warfarin-treated patient at an increased and unnecessary risk of bleeding or thromboembolic complications. This management issue is largely due to variations in measuring the pro-thrombin time. ⋯ This article focuses on the appropriate use of the INR to monitor patients' responses to warfarin sodium therapy. It is vitally important for health care providers to be aware of the INR, to use it in clinical practice, and to interpret it correctly.
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J. Cardiothorac. Vasc. Anesth. · Aug 1995
Comparative StudyDetermination of normal versus abnormal activated partial thromboplastin time and prothrombin time after cardiopulmonary bypass.
The study's objective was to determine the prothrombin time (PT) and activated partial thromboplastin time (aPTT) values that differentiated normal from excessively bleeding patients immediately after cardiopulmonary bypass (CPB). ⋯ The aPTT and PT values that produce the maximal sensitivity and specificity in the ROC analysis may be helpful to differentiate patients who are bleeding excessively from those patients who are not after CPB and to guide transfusion of blood products. New whole blood coagulation devices with rapid turn-around times had similar predictive value for bleeding tendency compared with standardized laboratory tests.
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Antiphospholipid (aPL) antibodies include anticardiolipin (aCL) and lupus anticoagulant (LA) antibodies. LA antibodies recognize the complex of lipid-bound (human) prothrombin, in this way inhibiting the phospholipid-dependent coagulation reactions, whereas aCL antibodies are directed towards beta 2-glycoprotein I (beta 2-GPI) bound to an anionic lipid surface. According to their behavior in coagulation reactions, we have divided aCL antibodies into two groups: aCL-type A, which inhibit the phospholipid-dependent coagulation reactions because they enhance the binding of beta 2-GPI to the procoagulant phospholipid surface; and aCL-type B antibodies, which are devoid of anticoagulant properties. ⋯ We ruled out the possibility that platelet contamination of plasma could account for the observed coagulation profiles, as the two patterns were reproduced in platelet-free plasma. In addition, we performed clotting tests in plasma in the presence of phospholipids and calcium after addition of factor IXa or factor Xa. The assay performed with factor Xa was more sensitive to the presence of aCL-type A antibodies, while the assay performed with factor IXa was preferentially sensitive to LA-containing plasmas, supporting the earlier findings with the dRVVT and KCT assays.(ABSTRACT TRUNCATED AT 400 WORDS)
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Anesthesia and analgesia · Feb 1995
Packed red cells in acute blood loss: dilutional coagulopathy as a cause of surgical bleeding.
The purpose of this study was: 1) to define coagulation abnormalities in patients who receive red cell concentrates rather than whole blood for large volume blood loss (greater than 0.5 blood volume); and 2) to determine when coagulation abnormalities lead to increased bleeding in the massively transfused surgical patient. We studied 32 ASA physical status I or II patients (mean age 15.6 +/- 2.3 yr) who lost more than 50% of their blood volume during elective posterior spinal stabilization. Crystalloid solutions and packed red cell concentrates were used to replace blood and fluid losses. ⋯ A coagulation profile (prothrombin time [PT] and activated partial thromboplastin time [aPTT], platelet count, and fibrinogen) was measured at the conclusion of operation in these patients. In 17 patients, increased surgical bleeding as a result of decreased clot formation and increased bleeding from the wound was present. In these 17 patients at the time increased bleeding was diagnosed, hemostatic tests (PT, aPTT, fibrinogen, platelet count, and coagulation factor assays V, VIII, and IX) were obtained.(ABSTRACT TRUNCATED AT 250 WORDS)
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The contribution of platelet dysfunction to the impaired hemostasis after cardiac surgery remains to be established, because there is no sensitive method to assess platelet function. Measurement of the shear-induced pathway of platelet function, an important mechanism in inducing hemostasis, became possible by a novel shear-inducing technique, the in-vitro bleeding test (Thrombostat 4000). By using this test, the changes in platelet function during cardiopulmonary bypass and their contribution to hemostasis were investigated in patients undergoing cardiac surgery. ⋯ These results indicate the significant and variable effects of cardiopulmonary bypass on the shear-induced pathway of platelet function. Moreover, the impairment of this function of platelets appears to be a major cause of excessive bleeding in patients after cardiac surgery. Therefore, the routine use of the shear-inducing test seems helpful to make a proper diagnosis and design the therapy for bleeders after cardiac surgery.