scholarly journals Preparation of lyophilized partial thromboplastin time reagent composed of synthetic phospholipids: usefulness for monitoring heparin therapy

1997 ◽  
Vol 43 (7) ◽  
pp. 1215-1222 ◽  
Author(s):  
Anton M H P van den Besselaar ◽  
Jacoline Neuteboom ◽  
Joyce Meeuwisse-Braun ◽  
Rogier M Bertina
Keyword(s):  
Oral Anticoagulation ◽  
Partial Thromboplastin Time ◽  
Colloidal Silica ◽  
Factor Xa ◽  
Heparin Therapy ◽  
International Committee ◽  
Heat Degradation ◽  
Intravenous Heparin ◽  
Aptt Reagent ◽  
Apparently Healthy

Abstract To contribute to the development of a reference reagent for monitoring heparin therapy, a lyophilized partial thromboplastin time (PTT) reagent was prepared from synthetic dioleoylphosphatidylcholine, dioleoylphosphatidylserine, and dioleoylphosphatidylethanolamine, with colloidal silica as activator. The reagent, coded 91/558, was contained in sealed glass ampoules; it deteriorated in a heat degradation experiment, but its activity remained constant for at least 4 years when stored at −70 °C. Within- and between-run precision with this reagent complied with the requirements proposed by the International Committee for Standardization in Haematology (ICSH) Panel on PTT. The response of this reagent and of two other reagents to heparin added to pooled normal plasma was nonlinear. Citrated samples from 58 patients receiving intravenous heparin and from 24 apparently healthy volunteers were tested with reagent 91/558, with Automated APTT (Organon Teknika), with Manchester APTT reagent, with an anti-factor Xa assay, and with an anti-factor IIa assay. The correlation of APTT with anti-Xa and anti-IIa activity was poor. The best correlation was observed between reagent 91/558 and the Organon Teknika reagent. Correlations were improved when individual patients’ samples were replaced by pooled plasmas from heparinized patients, in whom the effect of oral anticoagulation was minimal. These results suggest that preparation of a lyophilized synthetic phospholipid reagent is feasible for use in monitoring heparin therapy.

scholarly journals Design and Implementation of an Anti–Factor Xa Heparin Monitoring Protocol

2020 ◽  
Vol 31 (2) ◽  
pp. 129-137
Author(s):  
Tanya Williams-Norwood ◽  
Megan Caswell ◽  
Barbara Milner ◽  
Joseph C. Vescera ◽  
Kelly Prymicz ◽  
...  
Keyword(s):  
Unfractionated Heparin ◽  
Partial Thromboplastin Time ◽  
Factor Xa ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Monitoring Protocol ◽  
Protocol Conversion ◽  
Therapeutic Anticoagulation ◽  
Intravenous Heparin ◽  
Heparin Dosage

Background: The VA Northeast Ohio Healthcare System introduced a new nurse-driven anti–factor Xa (anti-Xa) protocol for monitoring unfractionated heparin to replace the previous activated partial thromboplastin time protocol. Objective: To design, implement, and evaluate the efficacy of the anti-Xa monitoring protocol. Methods: An interdisciplinary team of providers collaborated to develop and implement a nurse-driven, facility-wide anti–factor Xa protocol for monitoring unfractionated heparin therapy. The effectiveness of this protocol was evaluated by retrospective analysis. Results: We reviewed 100 medical records for compliance with the new anti-Xa monitoring protocol. We then evaluated 178 patients whose anticoagulation was monitored with the anti-Xa assay to determine the time to therapeutic range. We found that 80% of patients receiving the anti-Xa protocol achieved therapeutic anticoagulation within 24 hours, as compared with 54% of patients receiving the activated partial thromboplastin time protocol (P < .001). Protocol conversion also yielded a decrease in blood draws, dose adjustments, and potential calculation errors. Conclusions: Monitoring intravenous heparin therapy with the anti-Xa assay rather than activated partial thromboplastin time resulted in a shorter time to therapeutic anticoagulation, longer maintenance of therapeutic levels, and fewer laboratory tests and heparin dosage changes. We believe the current practice of monitoring heparin treatment with activated partial thromboplastin time assays should be reexamined.

scholarly journals Discordance in activated partial thromboplastin time and anti-factor Xa levels in COVID-19 patients on heparin therapy

2021 ◽  
Vol 198 ◽  
pp. 79-82
Author(s):  
Matthew Lawlor ◽  
Aakriti Gupta ◽  
Lauren S. Ranard ◽  
Mahesh V. Madhavan ◽  
Jianhua Li ◽  
...  
Keyword(s):  
Partial Thromboplastin Time ◽  
Factor Xa ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time

Clinical safety and cost of heparin titration using bedside activated clotting time

1993 ◽  
Vol 2 (1) ◽  
pp. 81-87 ◽  
Author(s):  
T Thomason ◽  
B Riegel ◽  
D Jessen ◽  
Smith SCJr ◽  
I Gocka ◽  
...  
Keyword(s):  
Partial Thromboplastin Time ◽  
Percutaneous Transluminal Coronary Angioplasty ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Clotting Time ◽  
Clinical Safety ◽  
Activated Clotting Time ◽  
Intravenous Heparin ◽  
Transluminal Coronary Angioplasty ◽  
Percutaneous Transluminal

OBJECTIVE: To evaluate the clinical safety of heparin titration and the procedural cost of anticoagulation measurement using bedside low-range activated clotting time. DESIGN: Quasi-experimental study using data gathered through retrospective record review. SETTING: Coronary care, medical intensive care and telemetry units of a community hospital. SUBJECTS: Sample of 102 patients undergoing elective percutaneous transluminal coronary angioplasty. INTERVENTION: Intravenous heparin therapy was titrated using low-range activated clotting time in 51 percutaneous transluminal coronary angioplasty patients. Data from this group were compared to a matched sample of 51 angioplasty patients whose intravenous heparin therapy was titrated using activated partial thromboplastin time. RESULTS: No differences in procedural, early or late complications were found between the groups. The cost of managing heparin therapy with low-range activated clotting time was less than with activated partial thromboplastin time. CONCLUSION: These results suggest that titrating heparin therapy based on bedside low-range activated clotting time for the angioplasty patients in this sample was as safe as with activated partial thromboplastin time. Use of bedside low-range activated clotting time saved money for the hospital.

State-of-the-Art Review : Monitoring of High-Dose Intravenous Heparin Therapy—A Contribution to the Safety of Heparin Monitoring

1996 ◽  
Vol 2 (3) ◽  
pp. 177-184 ◽  
Author(s):  
Alexander Haushofer ◽  
Walter Michael Halbmayer ◽  
Johannes Radek ◽  
Michael Fischer
Keyword(s):  
Heparin Therapy ◽  
Therapeutic Drug ◽  
High Dose ◽  
Sensitivity Testing ◽  
Therapeutic Ratio ◽  
Intravenous Heparin ◽  
Sensitivity Curves ◽  
Chemical Conditions ◽  
Aptt Reagent ◽  
Therapeutic Doses

Whenever unfractionated heparin (UFH) is administered i.v. in therapeutic doses, therapeutic drug monitoring of the anticoagulant response should be man datory and the dose should be adjusted accordingly. UFH therapy is usually monitored by the activated partial thromboplastin time (APTT). A 1.5- to 2.5-fold prolonga tion of APTT has become generally accepted as an indi cator of effective i.v. anticoagulation, but it has become common to recommend this ratio without testing the APTT reagents used for their heparin sensitivity and for their actual therapeutic APTT ratio (actual APTT: normal control APTT). Internal heparin sensitivity testing of APTT reagents is managed using heparin sensitivity curves obtained from heparin-spiked normal plasma pool. The most common APTT reagents in Austria and a newly developed double activated APTT reagent were tested for their heparin sensitivity and therapeutic ratios on differ ent automated analyzers, depending on their optical and chemical conditions. Also, newly developed, commer cially prepared heparin standards (0.19, 0.52, 0.86 IU heparin/ml plasma) were tested. APTT reagents differ in their heparin sensitivity and therapeutic ratio; variations in heparin sensitivity are also seen between different an alyzers. Therefore, therapeutic ratio should regularly be checked and the literature should always state which APTT reagent was used on which instrument.

Monitoring of Heparin Therapy with the Activated Partial Thromboplastin Time and Chromogenic Substrate Assays

1987 ◽  
Vol 58 (03) ◽  
pp. 853-855 ◽  
Author(s):  
Martin F Fey ◽  
Mathis Lang ◽  
Miha Furlan ◽  
Eugen A Beck
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Surgery ◽  
Partial Thromboplastin Time ◽  
Factor Xa ◽  
Underlying Disease ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Chromogenic Substrate ◽  
Group A ◽  
Plasma Heparin

SummaryHeparin therapy was monitored with the activated partial thromboplastin time (APTT) and with chromogenic substrate assays (factor Xa and factor Ha inhibition) in 100 plasma samples from 47 patients. Heparin concentrations were classified as being below, within or above a defined therapeutic range (TR; 0.2-0.55 units heparin/ml). In a first group of patients (A), all three assays allocated the plasma heparin levels to the same concentration interval with respect to the TR. The most frequent diagnoses in group A were uncomplicated arterial or venous thromboembolism, myocardial infarction with limited tissue necrosis, cardiac surgery without major complications and successfully treated infectious disease. In a second group of patients (B), the results of APTT suggested higher heparin concentrations with respect to the TR than the chromogenic assays. Predominant diagnoses were severe infectious diseases, severe liver disorders, extensive myocardial infarction and postoperative complications after cardiac surgery. The discrepancy between heparin concentrations determined by either APTT or the chromogenic substrate assays is most likely due to a non-heparin related prolongation of APTT caused by the underlying disease.

ACTIVATED PARTIAL THROMBOPLASTIN TIME MONITORING OF HEPARIN THERAPY: COMPARISON OF INSTRUMENTS AND REAGENTS

1987 ◽  
Author(s):  
M P Seveso ◽  
A Macagni ◽  
S Viganò D’Angelo ◽  
A G Dettori ◽  
P A Bonini ◽  
...  
Keyword(s):  
Clinical Practice ◽  
Liver Disease ◽  
Partial Thromboplastin Time ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Large Majority ◽  
Laboratory Monitoring ◽  
Current Clinical Practice ◽  
F Test ◽  
Aptt Reagent

It is current clinical practice to monitor heparin therapy by maintainig the activated partial thromboplastin time (APTT) at 1.5-2.5 × control normal pool. There is however controversy regarding the choice of reagents with respect to their heparin sensitivity. Choice of instrumentation is also known to affect the results. We have compared two automatic coagulometers, the ACL (Instrumentation Laboratory), a laser-nephelometric centrifugal analyzer and the KOAGULAB 40A (Ortho Diagnostics), an optical automatic coagulometer, with the tilt tube technique for the performance of APTT. Seven commercial reagents have been used for APTT replicate determinations in 30 normals, 30 liver disease patients and 30 patients on heparin therapy (20-40,000 IU daily). The overall observed imprecision (C. V.)was 1.8% for ACL, 3.0% for KOAGULAB 40A and 2.3% for tilt tube technique. The F test for the two-way interaction of ratios was statistically significant (p<0.001) for the large majority of reagent/ technique combinations in normals, liver disease and heparin treated patients. The percentage of patients adequately, inadequately and excessively heparinazed obtained with the two automatic instruments and with the tilt tube technique were not sig nificantly different when using the same reagent. However, major differences were observed when comparing the different reagents. For instance, inadequately heparinized patients were 90% according to one reagent (Cephotest, Nyegaard) as opposed to 17% according to another reagent (APTT, Instrumentation Laboratory). These results stress the need for a standardized APTT reagent to provide effective laboratory monitoring of heparin treatment. .

scholarly journals Discordance between aPTT and anti-factor Xa levels and implications in patients receiving intravenous unfractionated heparin therapy

2019 ◽  
Vol 7 (30) ◽  
pp. 12-18
Author(s):  
Akwasi Opoku ◽  
Kenneth Iwuji ◽  
Brendon Clough ◽  
Jacqueline Le ◽  
McKenzie Moore ◽  
...  
Keyword(s):  
Unfractionated Heparin ◽  
Partial Thromboplastin Time ◽  
Factor Xa ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Clinical Implications ◽  
Clotting Factors ◽  
Monitoring Protocols ◽  
Plasma Heparin

Heparin, one of the world’s oldest anticoagulation medications, accelerates the rate ofinhibition of previously activated clotting factors. It is most often used in the prophylaxis andtreatment of thromboembolic disorders and complications associated with atrial fibrillation.The two most common ways to monitor plasma heparin levels and anticoagulation therapyare the activated partial thromboplastin time (aPTT) and anti-factor Xa assay (anti-Xa). Thisarticle assesses the performance of aPTT and anti-Xa monitoring protocols and analyzes thediscordance between aPTT and anti-Xa levels and its clinical implications in patients receivingintravenous heparin therapy.

The uncalibrated prothrombinase-induced clotting time test

2010 ◽  
Vol 30 (04) ◽  
pp. 212-216 ◽  
Author(s):  
R. Jovic ◽  
M. Hollenstein ◽  
P. Degiacomi ◽  
M. Gautschi ◽  
A. Ferrández ◽  
...  
Keyword(s):  
Factor Xa ◽  
Heparin Therapy ◽  
Thrombin Inhibitors ◽  
Coagulation Cascade ◽  
Diagnostic Tools ◽  
Direct Thrombin Inhibitors ◽  
Functional Assay ◽  
Clotting Time ◽  
Coagulation Time ◽  
Time Test

SummaryThe activated partial thromboplastin time test (aPTT) represents one of the most commonly used diagnostic tools in order to monitor patients undergoing heparin therapy. Expression of aPTT coagulation time in seconds represents common practice in order to evaluate the integrity of the coagulation cascade. The prolongation of the aPTT thus can indicate whether or not the heparin level is likely to be within therapeutic range. Unfortunately aPTT results are highly variable depending on patient properties, manufacturer, different reagents and instruments among others but most importantly aPTT’s dose response curve to heparin often lacks linearity. Furthermore, aPTT assays are insensitive to drugs such as, for example, low molecular weight heparin (LMWH) and direct factor Xa (FXa) inhibitors among others. On the other hand, the protrombinase-induced clotting time assay (PiCT®) has been show to be a reliable functional assay sensitive to all heparinoids as well as direct thrombin inhibitors (DTIs). So far, the commercially available PiCT assay (Pefakit®-PiCT®, DSM Nutritional Products Ltd. Branch Pentapharm, Basel, Switzerland) is designed to express results in terms of units with the help of specific calibrators, while aPTT results are most commonly expressed as coagulation time in seconds. In this report, we describe the results of a pilot study indicating that the Pefakit PiCT UC assay is superior to the aPTT for the efficient monitoring of patients undergoing UFH therapy; it is also suitable to determine and quantitate the effect of LMWH therapy. This indicates a distinct benefit when using this new approach over the use of aPPT for heparin monitoring.

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