The progress of prothrombin time measurement

Abstract

Warfarin is the most widely used medicine for oral anticoagulant therapy (OAT). It inhibits the synthesis of coagulation factors II, VII, IX, and X in the liver and results in the production of inactive or partially active versions of these factors. Inactive coagulation factors interfere with prothrombin time measurement (Quick and Owren PT) measuring the sum of coagulation activity and inhibition. The narrow therapeutic range here involves a danger of serious complications and the risk of bleeding or thrombosis. The new-generation PT method can measure coagulation activity and inhibition separately. This new technique promotes patient care and anticoagulant medication (warfarin, dicoumarol) based on coagulation activity in vivo. Both therapy and laboratory controls should be unquestionably accurate and based solely on in vivo coagulation activity. Inactive coagulation factors (inhibition) render measurement, calibration, and harmonization. The use of the new-generation PT method based on measurement of coagulation activity in vivo could develop vitamin K antagonist (VKA) therapy for the marked benefit of patients.

Anticoagulation: Past, Present, and Future Therapies

“…Dosing considerations for heparin depend on factors such as patient weight, age, and medical condition, with dose adjustments guided by activated partial thromboplastin time (aPTT) or anti-factor Xa levels [19]. Landmarks developments in anticoagulation research and therapy [8][9][10][11][12][13][14][15].…”

The Choice between Plasma-Based Common Coagulation Tests and Cell-Based Viscoelastic Tests in Monitoring Hemostatic Competence: Not an either–or Proposition

“…2 57 58 59 60 Nevertheless, anti-Xa assays have been proposed as an accurate method of monitoring unfractionated heparin in cases of heparin resistance, lupus anticoagulant, and in other clinical circumstances. 1 2 57 61 62 63 64 65 66 67 While TEG and ROTEM do not correlate with the PT for patients on warfarin, they have been used with success in treating surgical and medical patients who are on unfractionated heparin. 11 68 69 70 71…”

“…During clot formation, fibrin polymers attach to the wall of the cup and to the pin, creating torsion as the system rotates (►Fig. 1). Two of the most common platforms that directly assess the measures of elastic shear are TEG 5000 and ROTEM.…”

“…CCTs are considered highly reproducible, and they generally are not associated with operator error. 1 2 3 7 16 However, their longer turnaround time may result in improperly balanced transfusion of scarce blood components which increases blood product waste, treatment costs, morbidity, and mortality. 7 29 30 CCTs only provide a single snapshot in time and shed light on a fraction of the entire coagulation process in the formation of the lifespan of the clot.…”

“…These plasma-based models were based on a reductionist approach which primarily emphasized the role of clotting factors. [1][2][3][4] The common coagulation tests (CCTs)-partial thromboplastin time (PTT), international normalized ratio (INR), and prothrombin time (PT)-provide a plasma-based assessment of clotting factor activity. CCTs evaluate only the first 5 to 10% of fibrin formation and do not assess clot strength/stability, the activity of natural anticoagulants, or the complex interaction between the endothelium, platelets, and clotting factors.…”