Using anti-Xa level for adjusting intravenous unfractionated heparin infusion in peripartum thromboembolic disease

Background Intravenous unfractionated heparin infusion is often used to minimize the duration of time without anticoagulation around delivery in pregnant patients with high thrombotic risk. Activated partial thromboplastin time is commonly used to monitor and adjust heparin dose. However, using activated partial thromboplastin time is problematic in pregnancy because activated partial thromboplastin time response to unfractionated heparin is attenuated due to elevated Factor VIII levels and may lead to incorrect dosing. Case We report a case of deep venous thrombosis occurring in a term pregnancy managed by intravenous unfractionated heparin adjusted using anti-Xa level around the time of delivery. We modified the intravenous unfractionated heparin nomogram by using anti-Xa levels instead of activated partial thromboplastin time and observed lower dosing of unfractionated heparin than otherwise required to achieve and maintain target levels. Conclusion This report demonstrates the feasibility and effectiveness of using anti-Xa level to monitor and adjust intravenous unfractionated heparin infusion in pregnancy.

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The Therapeutic Range for Heparin Therapy: Relationship between Six Activated Partial Thromboplastin Time Reagents and Two Heparin Assays

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650358 ◽

1996 ◽

Vol 75 (05) ◽

pp. 734-739 ◽

Cited By ~ 60

Author(s):

S Kitchen ◽

F E Preston

Keyword(s):

Unfractionated Heparin ◽

Therapeutic Range ◽

Partial Thromboplastin Time ◽

Warfarin Therapy ◽

Normal Subjects ◽

Heparin Therapy ◽

Thromboembolic Disease ◽

Activated Partial Thromboplastin Time ◽

Therapy Relationship ◽

The Relationship

SummaryThe activated partial thromboplastin time (APTT) is the most commonly used test for laboratory monitoring of unfractionated heparin therapy. Since there are differences between APTT reagents in respect of responsiveness to heparin the widely used therapeutic range of 1.5-2.5 (APTT ratios) may not be appropriate for all reagents.The aim of this study was to assess the relationship between 6 different APTT reagents using a manual technique, 2 of these reagents used in combination with a coagulometer, a heparin assay by protamine titration and a chromogenic anti-Xa assay. Samples from 42 patients treated with unfractionated heparin for thromboembolic disease were studied, 12 of whom were receiving warfarin therapy with International Normalised Ratios (INR) of >1.3.For normal subjects, APTT results were highly dependent on the method used and statistically significant differences were noted. The ratio of patient to mean normal APTT was calculated for each APTT method. When 30 samples from heparinised patients (with INRs of <1.3) were analysed manually, the APTT ranges equivalent to 0.2-0.4 u/ml heparin by protamine titration (by regression analysis) were 1.6-1.9 for Boehringer reagent (the least responsive) up to 2.2-2.9 for Instrumentation Laboratory reagent (the most responsive). The concentration of heparin associated on average with APTT ratios of 1.5-2.5 varied approximately twofold to threefold between reagents.

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The use of activated partial thromboplastin time versus antifactor Xa assay in monitoring continuous unfractionated heparin infusion therapy in obstetric intensive care unit

Ain-Shams Journal of Anesthesiology ◽

10.1186/s42077-019-0021-2 ◽

2019 ◽

Vol 11 (1) ◽

Author(s):

Hany V. Zaki ◽

Marwa A.K. Elbeialy ◽

Ahmed M. Soliman

Keyword(s):

Intensive Care Unit ◽

Intensive Care ◽

Unfractionated Heparin ◽

Partial Thromboplastin Time ◽

Activated Partial Thromboplastin Time ◽

Infusion Therapy ◽

Heparin Infusion ◽

Antifactor Xa

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Monitoring Heparin Therapy: Relationships between the Activated Partial Thromboplastin Time and Heparin Assays Based on Ex-Vivo Heparin Samples

Thrombosis and Haemostasis ◽

10.1055/s-0038-1645678 ◽

1990 ◽

Vol 63 (01) ◽

pp. 016-023 ◽

Cited By ~ 41

Author(s):

A M H P van den Bessekaar ◽

J Meeuwisse-Braun ◽

R M Bertina

Keyword(s):

Partial Thromboplastin Time ◽

Plasma Sample ◽

Ex Vivo ◽

Correlation Coefficients ◽

Heparin Therapy ◽

Thromboembolic Disease ◽

Activated Partial Thromboplastin Time ◽

Venous Thromboembolic Disease ◽

Venous Thromboembolic

SummaryFive different APTT reagents, two amidolytic anti-ITa assays, one amidoiytic anti-Xa assay, and one coagulometric anti-Xa/ anti-IIa assay were used to assess the effect of heparin in patients treated for venous thromboembolic disease. Good correlations were observed between lug-transformed APYE> determined with the various reagents (correlation coefficients: 0.92-0.96).Nevertheless there were important differences in the slopes of the lines of relationship between the APTT reagents.Good correlations were observed between the anti-Xa and anti-IIa assay results (correlation coefficients: 0.92-0.97). However, the amidolytic anti-Xa activity was significantly higher (p <0.001) than the two amidolytic anti-IIa activities. Less good correlations were observed between the log-transformed APTTs and the anti-Xa or anti-IIa activities (correlation coefficients: 0.64-0.78). The correlations were improved by transforming the APTT into APTT-ratio, i.e. the ratio of the patient’s APTT to the same patient’s APTT after removal of heparin from the plasma sample by means of ECTEOLA-cellulose treatment. The correlation coefficients of log (AFTT-ratio) with anti-Xa or anti-IIa ranged from 0.76 to 0.87.For both APTT and amidolytic heparin assay, the response to in vitro heparin was different from the response to ex vivo heparin.Therefore, equivalent therapeutic ranges should be assessed by using ex vivo samples rather than in vitro heparin. Because of the response differences between the APTT reagents, it is not adequate to define a therapeutic range for heparin therapy without specification of the reagent.

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