Articles: prothrombin-time.
-
The international normalized ratio, or INR, was introduced in 1983 by the World Health Organization, or WHO, Committee on Biological Standards to more accurately assess patients receiving anticoagulation therapy. The INR mandates the universal standardization of prothrombin time. This article describes the method used to calculate INR, as well as its clinical relevance to the practice of dentistry.
-
A patient with a greatly prolonged international normalised ratio (INR) during the combined use of warfarin and indomethacin is described. In patients on warfarin, non-steroidal anti-inflammatory drugs (NSAIDs) should be avoided as far as possible. If NSAIDs are absolutely necessary, patients should be closely monitored for prolongation of INR and bleeding.
-
Int. J. Pediatr. Otorhinolaryngol. · Feb 1997
The utility of preoperative hemostatic assessment in adenotonsillectomy.
Routine preoperative coagulation screening in patients undergoing tonsillectomy and/or adenoidectomy (T and A) is considered by some to be mandatory. T and A is often the first hemostatic challenge in children; therefore, screening is thought to be useful in predicting patients who may experience postoperative hemorrhage. On the other hand, in today's cost-conscious medical environment, routine screening is considered by some to be an unnecessary added expense. ⋯ Preoperative PT/PTT did not predict intraoperative or postoperative bleeding. In our experience, laboratory screening has a very low positive predictive value in detecting occult bleeding disorders or perioperative hemorrhage; thus, we feel it should be used selectively. Routine preoperative PT/PTT is not recommended to screen T and A patients and does not appear to be cost-effective.
-
Blood Coagul. Fibrinolysis · Jun 1996
Multicenter StudyMulticentric evaluation of heparinase on aPTT, thrombin clotting time and a new PT reagent based on recombinant human tissue factor.
In a multicentric study the influence of heparinase (Hepzyme) was evaluated on activated partial thromboplastin time, thrombin clotting time and prothrombin time using the recombinant human tissue factor and synthetic phospholipid (phosphatidylcholine and phosphatidyl-serine reagent). Hepzyme itself does not have any influence on normal coagulation values of activated partial thromboplastin time (aPTT) and prothrombin time (PT) assays whereas thrombin clotting time was prolonged by 10% (n = 60). In patients treated with unfractionated heparin for recent deep vein thrombosis (n = 47), plasma levels of aPTT, PT and thrombin clotting time (TCT) returned to the normal range in 100%, 97% and 91% after treatment with heparinase, respectively. ⋯ Freezing of plasma samples after treatment with heparinase resulted in a prolongation of the coagulation times in 15% of PT, 7% of aPTT and not of TCT values. The results show that treatment of plasma samples with heparinase abolishes the effect of unfractionated and low molecular weight heparin in vitro and ex vivo in patients during simultaneous treatment with oral anticoagulants. The use of heparinase may be of significance in patients with concomitant treatment of heparin and oral anticoagulants.
-
In order to harmonize the prothrombin time (PT) reporting systems, the World Health Organization, in collaboration with the International Committee on Thrombosis and Hemostasis, and the International Council on the Standardization in Hematology proposed a reporting system, the so-called international normalized ratio (INR). As the calculation of the INR depends on mathematical formula requiring a special calculator or mathematic tables, its derivation is associated with some difficulties and errors. In this article a nomogram is presented, by which derivation of the INR from different PT reporting methods can be easily done within a few seconds.