Optimal Therapeutic Level of Heparin Therapy in Patients With Venous Thrombosis

Abstract

Our findings demonstrate that no association exists between supratherapeutic APTT responses and bleeding, which is in direct contrast to the observed association between subtherapeutic APTT responses and recurrent venous thromboembolism.

Heparin and Low-Molecular-Weight Heparin Therapy for Venous Thromboembolism: Will Unfractionated Heparin Survive?

“…12,14,27 Treatment is further complicated by the fact that the aPTT response exhibits diurnal variation in patients who receive a constant infusion of intravenous heparin. 28 A peak response occurs at 3 AM, and if the heparin infusion is reduced in response to the high aPTT, levels could be subtherapeutic later in the day. 28 Sensitivity varies widely for the various thromboplastins used to perform the aPTT; even with the same thromboplastin, different coagulometers may yield different results.…”

“…28 A peak response occurs at 3 AM, and if the heparin infusion is reduced in response to the high aPTT, levels could be subtherapeutic later in the day. 28 Sensitivity varies widely for the various thromboplastins used to perform the aPTT; even with the same thromboplastin, different coagulometers may yield different results. 29 Therefore, each laboratory must correlate its aPTT results with a therapeutic range of 0.35 to 0.70 U/mL.…”

“…29 Although subtherapeutic aPTT values correlate strongly with recurrent thromboembolism, the relationship between supratherapeutic aPTT and bleeding (aPTT ratio 2.5 or more) is less definite. 28 Indeed, bleeding during heparin therapy more closely relates to underlying clinical risk factors than to aPTT elevation above the therapeutic range. 28,30,31 The main adverse effects of unfractionated heparin therapy include bleeding, thrombocytopenia, and osteoporosis.…”

“…28 Indeed, bleeding during heparin therapy more closely relates to underlying clinical risk factors than to aPTT elevation above the therapeutic range. 28,30,31 The main adverse effects of unfractionated heparin therapy include bleeding, thrombocytopenia, and osteoporosis. Patients predisposed to bleeding associated with heparin therapy include those who have had recent surgery or trauma, or who have other clinical factors, such as peptic ulcer, occult malignancy, liver disease, hemostatic defects, age >65 years, or female gender.…”

“…Patients predisposed to bleeding associated with heparin therapy include those who have had recent surgery or trauma, or who have other clinical factors, such as peptic ulcer, occult malignancy, liver disease, hemostatic defects, age >65 years, or female gender. 28,31 The management of this bleeding depends on its location and severity, the risk of recurrent VTE, and the aPTT results. If bleeding occurs, heparin should be discontinued temporarily or permanently, and those patients with recent VTE may be candidates for inser-tion of an inferior vena cava filter.…”