Thrombolytic

6 c. apTT is the activated partial thromboplastin time test which is used to determine the most effective dosage of some medication such as heparin that prevent blood clots. When activators are used the test is called apTT. The test is termed partial due to the absence of the tissue factors from the reaction mixture. Mixing studies are performed in which a patient's plasma is initially mixed at 50:50 dilution with normal plasma. The apTT also measures how well the coagulation sequences of the intrinsic pathway( factors Xll, Xl, lX,Vlll ) and the common pathway ( factors X, V, ll, and fibrinogen ) are functioning. An elevated apTT could indicate disorders of any coagulation factors except Vll and Xlll. Clinical condition associated with an elevated apTT include DIC, von Willebrand's disease, and liver disease. Drugs that may affect apTT include chlorpromazine, codeine, phenothiazine, salicylate, and warfarin. But it is used to monitor the patient's response to heparin therapy.

The target apTT values for a patient with a pulmonary embolism ( PE ) depends on the amount of heparin given. For example, for subcutenaneous treatment with unfractioned heparin, 250 U/kg is given every 12 hours to obtain an apTT with the therapeutic range at 6to8 hours. The heparin dosage should prolong the apTT to range that corresponds to a plasma heparin level of 0.2 to 0.4 U/ml, by protamine sulfate, or 0.3 to 0.6 U/ml, by amidolytie anti-factor Xa assay (grade Al ).

6. D. Thromolytic agents are agents which dissolve blood clots. All thrombolytic agents act systematically and have the potential to lyse a fresh platelet-fibrin clot anywhere and cause bleeding at the site.. Their therapy is only recommended for patients with acute massive pulmonary embolism who are hemodynamically unstable and not prone to bleeding. Intracranial disease, recent surgery, trauma, and hemorrhagic disease are contraindicated to thrombolytic therapy. The approved thrombolytic agents to treat PE and venous thromboembolism are: urokinase, streptokinase, and recombinant tissue plasminogen activator (tPA). Heparin therapy is not administered concurrently with thrombolytics, however, thrombolytic therapy is followed by administration of heparin then warfarin.