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Arachchillage DJ, Kitchen S. Pleiotropic Effects of Heparin and its Monitoring in the Clinical Practice. Semin Thromb Hemost 2024. [PMID: 38810964 DOI: 10.1055/s-0044-1786990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Unfractionated heparin (UFH) was uncovered in 1916, has been used as an anticoagulant since 1935, and has been listed in the World Health Organization's Model List of Essential Medicines. Despite the availability of many other anticoagulants, the use of heparin (either low molecular weight heparin [LMWH] or UFH) is still substantial. Heparin has pleotropic effects including anticoagulant and several nonanticoagulant properties such as antiproliferative, anti-inflammatory activity, and anticomplement effects. Although UFH has been widely replaced by LMWH, UFH is still the preferred anticoagulant of choice for patients undergoing cardiopulmonary bypass surgery, extracorporeal membrane oxygenation, and patients with high-risk mechanical cardiac valves requiring temporary bridging with a parenteral anticoagulant. UFH is a highly negatively charged molecule and binds many positively charged molecules, hence has unpredictable pharmacokinetics, and variable anticoagulant effect on an individual patient basis. Therefore, anticoagulant effects of UFH may not be proportional to the dose of UFH given to any individual patient. In this review, we discuss the anticoagulant and nonanticoagulant activities of UFH, differences between UFH and LMWH, when to use UFH, different methods of monitoring the anticoagulant effects of UFH (including activated partial thromboplastin time, heparin anti-Xa activity level, and activated clotting time), while discussing pros and cons related to each method and comparison of clinical outcomes in patients treated with UFH monitored with different methods based on available evidence.
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Affiliation(s)
- Deepa J Arachchillage
- Centre for Haematology, Department of Immunology and Inflammation, Imperial College London, London, United Kingdom
- Department of Haematology, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Steve Kitchen
- Department of Coagulation, Royal Hallamshire Hospital, Sheffield, United Kingdom
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2
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Li C, Liu BT, Wang YT, Zhang TJ, Zheng X, Chen L, Li S, Tian X, Zhang D, Wang Y. A hydrogel-based ratiometric fluorescent sensor relying on rhodamine B labelled AIE-featured hyperbranched poly(amido amine) for heparin detection. Anal Chim Acta 2024; 1300:342466. [PMID: 38521573 DOI: 10.1016/j.aca.2024.342466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 02/22/2024] [Accepted: 03/10/2024] [Indexed: 03/25/2024]
Abstract
The fluorescent flexible sensor for point-of-care quantification of clinical anticoagulant drug, Heparin (Hep), is still an urgent need of breakthrough. In this research, a hyperbranched poly(amido amine) (HPA) was decorated with tetraphenylethene (TPE) and Rhodamine B (RhB), constructing a ratiometric fluorescent sensor (TR-HPA) for Hep. When the sensor was exposed to Hep, the TPE units within the probe skeleton would aggregate, resulting in an increasing fluorescent emission at 483 nm. The 580 nm of fluorescence came from RhB enhance, simultaneously, due to the fluorescence resonance energy transfer. As a result, there are two good linear correlation between the fluorescence emission ratio (E483/E580) of TR-HPA and the Hep concentration over a range of 0-1.0 μM, with a low limit of detection of 3.0 nM. Furthermore, we incorporate the TR-HPA probe into a polyvinyl alcohol (PVA) hydrogel matrix to create a flexible fluorescent sensing system platform, denoted as TR-HPA/PVA. This approach offers a straightforward visual detection method by causing a fluorescence color change from pink to blue when trace amounts of Hep are present. The hydrogel-based fluorescent sensor streamlines the detection procedures for Hep in biomedical applications. It shows great potential in rapid and point-of-care human blood clotting condition monitoring, making it suitable for next-generation wearable medical devices.
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Affiliation(s)
- Cheng Li
- Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Bai-Tong Liu
- Department of Chemistry, The University of Hong Kong, Hong Kong SAR, 999077, China
| | - Yi-Ting Wang
- Sinopec Research Institute of Petroleum Engineering, Beijing, 102206, China
| | - Tian-Jiao Zhang
- Laboratory of Advanced Optoelectronic Materials, Chemical Engineering and Materials Science, College of Chemistry, Soochow University, Suzhou, 215123, China
| | - Xiaochun Zheng
- Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Li Chen
- Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Shaobo Li
- Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Xiaoxian Tian
- Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Dequan Zhang
- Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
| | - Yong Wang
- Tianjin Key Laboratory of Molecular Optoelectronic Science, Department of Chemistry, School of Sciences, Tianjin University, Tianjin, 300354, China.
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Chiasakul T, Mullier F, Lecompte T, Nguyen P, Cuker A. Laboratory Monitoring of Heparin Anticoagulation in Hemodialysis: Rationale and Strategies. Semin Nephrol 2023; 43:151477. [PMID: 38290962 DOI: 10.1016/j.semnephrol.2023.151477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Unfractionated heparin (UFH) and low-molecular-weight heparins (LMWHs) are commonly used to prevent clotting of the hemodialysis extracorporeal circuit and optimize hemodialysis adequacy. There is no consensus on the optimal dosing for UFH and LMWHs during hemodialysis. In clinical practice, semiquantitative clotting scoring of the dialyzer and venous chamber may help to guide UFH and LMWH dose adjustment. Laboratory monitoring has not been shown to improve clinical outcomes and is therefore not routinely indicated in most hemodialysis patients. It might, however, be considered in select patients, such as those with extremes of body weight or history of repeated clotting or bleeding. Methods for laboratory monitoring include the activated partial thromboplastin time, activated clotting time, and antifactor Xa assays for UFH and antifactor Xa assay for LMWHs. Target ranges for anticoagulation in hemodialysis have been suggested but not clearly defined. When utilizing these tests, issues such as availability, standardization, interfering factors, and interpretation must be considered. In this narrative review, we discuss the rationale and methods of monitoring anticoagulation in hemodialysis.
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Affiliation(s)
- Thita Chiasakul
- Center of Excellence in Translational Hematology, Division of Hematology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand.
| | - François Mullier
- Namur Thrombosis and Hemostasis Center, Université Catholique de Louvain, Centre Hospitalier Universitaire UCL Namur, Hematology Laboratory, Yvoir, Belgium; Institut de Recherche Expérimentale et Clinique, Pôle Mont, Université Catholique de Louvain, Yvoir, Belgium
| | - Thomas Lecompte
- Pharmacy Department, University of Namur, Namur, Belgium; Université de Lorraine, Nancy, France
| | - Philippe Nguyen
- Hematology Laboratory, Reims University Hospital, Reims, France
| | - Adam Cuker
- Department of Medicine and Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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Monitoring of Unfractionated Heparin Therapy in the Intensive Care Unit Using a Point-of-Care aPTT: A Comparative, Longitudinal Observational Study with Laboratory-Based aPTT and Anti-Xa Activity Measurement. J Clin Med 2022; 11:jcm11051338. [PMID: 35268436 PMCID: PMC8911237 DOI: 10.3390/jcm11051338] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/20/2022] [Accepted: 02/26/2022] [Indexed: 12/18/2022] Open
Abstract
Continuous intravenous unfractionated heparin (UFH) is administered routinely in the intensive care unit (ICU) for the anticoagulation of patients, and monitoring is performed by the activated partial thromboplastin time (APTT) or anti-Xa activity. However, these strategies are associated with potentially large time intervals before dose adjustments, which could be detrimental to the patient. The aim of the study was to compare a point-of-care (POCT) version of the APTT to (i) laboratory-based APTT and (ii) measurements of anti-Xa activity in terms of correlation, agreement and turnaround time (TAT). Thirty-five ICU patients requiring UFH therapy were prospectively included and followed longitudinally for a maximum duration of 15 days. UFH was administered according to a local adaptation of Raschke and Amanzadeh’s aPTT nomograms. Simultaneous measurements of POCT-APTT (CoaguCheck® aPTT Test, Roche Diagnostics) on a drop of fresh whole blood, laboratory-based APTT (C.K. Prest®, Stago) and anti-Xa activity (STA®Liquid anti-Xa, Stago) were systematically performed two to six times a day. Antithrombin, C-reactive protein, fibrinogen, factor VIII and lupus anticoagulant were measured. The time tracking of sampling and analysis was recorded. The overall correlation between POCT-APTT and laboratory APTT (n = 795 pairs) was strongly positive (rs = 0.77, p < 0.0001), and between POCT-APTT and anti-Xa activity (n = 729 pairs) was weakly positive (rs = 0.46, p < 0.0001). Inter-method agreement (Cohen’s kappa (k)) between POCT and laboratory APTT was 0.27, and between POCT and anti-Xa activity was 0.30. The median TATs from sample collection to the lab delivery of results for lab-APTT and anti-Xa were 50.9 min (interquartile range (IQR), 38.4−69.1) and 66.3 min (IQR, 49.0−91.8), respectively, while the POCT delivered results in less than 5 min (p < 0.0001). Although the use of the POCT-APTT device significantly reduced the time to results, the results obtained were poorly consistent with those obtained by lab-APTT or anti-Xa activity, and therefore it should not be used with the nomograms developed for lab-APTT.
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Smahi M, De Pooter N, Hollestelle MJ, Toulon P. Monitoring unfractionated heparin therapy: Lack of standardization of anti-Xa activity reagents. J Thromb Haemost 2020; 18:2613-2621. [PMID: 32573889 DOI: 10.1111/jth.14969] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/02/2020] [Accepted: 06/08/2020] [Indexed: 11/28/2022]
Abstract
INTRODUCTION One of the main advantages of using anti-Xa instead of activated partial thromboplastin time in monitoring of unfractionated heparin (UFH) therapy relies on its hypothesized standardization, with a unique therapeutic range defined to be 0.30 to 0.70 IU/mL. The aim of the present study was to compare the inter-reagent agreement of anti-Xa activity. METHODS Citrate tubes were obtained from 104 inpatients on UFH. Plasma samples were stored frozen in aliquots at -70°C before being shipped to three accredited coagulation laboratories to be evaluated for anti-Xa activity using their routine assay(s). Pooled normal plasmas spiked with dilutions of the 6th International Standard of UFH to achieve anti-Xa activities up to 1.0 IU/mL were evaluated using the same techniques. RESULTS In the plasmas from patients on UFH, the median anti-Xa activity ranged from 0.37 IU/mL with one reagent to 0.57 IU/mL with another; results were in between (0.45 IU/mL) using two other reagents. Comparisons of results obtained using the different reagents demonstrated unacceptable bias up to 0.24 IU/mL between some reagents (41% difference). The concordance as whether anti-Xa activities measured using different reagents were within or outside the therapeutic range was between 0.411 and 0.939 (kappa). Similar discrepancy was demonstrated for anti-Xa activities when evaluating normal plasma spiked with the International Standard. A discrepancy of the same order of magnitude was demonstrated in the 2017 External Quality Assessment Program provided by the External Quality Control in Assays and Tests exercises. CONCLUSIONS The reported discrepancy between test results obtained using different anti-Xa assays clearly suggests a lack of standardization of that assay with potentially significant impact on the patients' anticoagulation.
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Affiliation(s)
- Motalib Smahi
- Hematology Department, Simone Veil Hospital, Eaubonne, France
| | | | - Martine J Hollestelle
- External quality Control for Assays and Tests (ECAT) Foundation, Voorschoten, The Netherlands
| | - Pierre Toulon
- Hematology Department, Université Côte d'Azur, CHU Nice, Nice, France
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McLaughlin K, Rimsans J, Sylvester KW, Fanikos J, Dorfman DM, Senna P, Connors JM, Goldhaber SZ. Evaluation of Antifactor-Xa Heparin Assay and Activated Partial Thromboplastin Time Values in Patients on Therapeutic Continuous Infusion Unfractionated Heparin Therapy. Clin Appl Thromb Hemost 2020; 25:1076029619876030. [PMID: 31530176 PMCID: PMC6829967 DOI: 10.1177/1076029619876030] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Clinical uncertainty exists regarding which assay should be designated as the standard
monitoring coagulation test for intravenous unfractionated heparin (UFH). Several studies
have compared the use of activated partial thromboplastin time (aPTT) and antifactor-Xa
(anti-Xa) and have come out with varying results. The correlation between these 2 tests
varied, markedly from strong to weak. Some have demonstrated that monitoring with anti-Xa
heparin assay leads to fewer dose adjustments, resulting in fewer laboratory tests, while
others have not. In the current study, we evaluated the correlation between aPTT and
anti-Xa values to guide clinical management of UFH, with the intention to develop a new
correlation nomogram.
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Affiliation(s)
- Kevin McLaughlin
- Department of Pharmacy, Brigham and Women's Hospital, Boston, MA, USA
| | - Jessica Rimsans
- Department of Pharmacy, Brigham and Women's Hospital, Boston, MA, USA
| | | | - John Fanikos
- Department of Pharmacy, Brigham and Women's Hospital, Boston, MA, USA
| | - David M Dorfman
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Patricia Senna
- Department of Clinical Laboratories, Brigham and Women's Hospital, Boston, MA, USA
| | - Jean M Connors
- Hematology Division, Brigham and Women's Hospital, Boston, MA, USA
| | - Samuel Z Goldhaber
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
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Abstract
Anticoagulant drugs directly or indirectly influence coagulation factors preventing fibrin formation, thus preventing blood clotting. They are classified into two groups according to the mode of application, namely parenteral and oral drugs. Among the latter, vitamin K antagonists (most often warfarin) were most widely used for almost a century. In recent years new oral anticoagulant drugs have become available that directly target either factor IIa or Xa (direct oral anticoagulants, DOACs). The proportion of patients to whom DOACs are prescribed is increasing because clinical studies have proved they are at least as effective and safe as vitamin K antagonists. Some of the anticoagulant drugs require regular laboratory monitoring, while others only need assessment of blood drug levels in specific clinical situations. This chapter provides an overview of appropriate laboratory tests used for either regular laboratory monitoring of therapy or occasional assessment of the anticoagulant effect of both parenteral and oral anticoagulant drugs used in clinical practice.
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Affiliation(s)
- Mojca Božič Mijovski
- Department of Vascular Diseases, Laboratory for Haemostasis and Atherothrombosis, University Medical Centre Ljubljana, Ljubljana, Slovenia.
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8
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Ratano D, Alberio L, Delodder F, Faouzi M, Berger MM. Agreement between activated partial thromboplastin time and anti-Xa activity in critically ill patients receiving therapeutic unfractionated heparin. Thromb Res 2019; 175:53-58. [PMID: 30708169 DOI: 10.1016/j.thromres.2019.01.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 12/04/2018] [Accepted: 01/03/2019] [Indexed: 10/27/2022]
Abstract
BACKGROUND No study supports the use of either aPTT or anti-Xa activity for heparin monitoring in critical care patients. There are no strong data on the agreement between aPTT and anti-Xa. The aims of this study were to: 1. Analyse the agreement between aPTT and anti-Xa in a large population of critically ill patients under unfractionated heparin therapy (UFH), 2. Identify clinical and biological factors associated to agreement or disagreement, and 3. Analyse the impact of anti-Xa availability on the use of aPTT and UFH therapy. METHODS Retrospective study in a 35 beds mixed-ICU population between 2006 and 2016 in a University teaching hospital. INCLUSION CRITERIA delivery of a UFH dose >15,000 U/24 h during at least one day with one anti-Xa determination. DATA demographic variables, aPTT, anti-Xa, laboratory variables, presence of extracorporeal devices (ECD). Pairs of simultaneously dosed aPTT and anti-Xa [aPTT:anti-Xa] were analysed on the basis of their agreement within the sub-therapeutic, therapeutic (aPTT 50-80″, anti-Xa 0.3-0.7 U/ml) or supra-therapeutic ranges. RESULTS 2283 patient admissions (2085 patients) were analysed. 35,595 [aPTT:anti-Xa] pairs were found. The overall [aPTT:anti-Xa] agreement was 59.6% and lowest (54.3%) in presence of ECD compared to non-ECD patients (61.6%; p < 0.001). Sixteen demographic and biological variables were analysed and were not predictive of [aPTT:anti-Xa] agreement. No significant difference in administered UFH dose was observed after anti-Xa introduction. CONCLUSION In this large cohort, the [aPTT:anti-Xa] agreement is <60% and significantly lower in patients with ECD. None of the variables identified as potentially affecting the agreement were predictive. Availability of anti-Xa had neither effect on aPTT use nor on UFH-dose. These results call for a prospective study to determine the optimal UFH-therapy monitoring tool.
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Affiliation(s)
- Damian Ratano
- Service of Intensive Care and Burn Unit, Lausanne University Hospital (CHUV) and Faculty of Biology & Medicine, University of Lausanne, Lausanne, Switzerland.
| | - Lorenzo Alberio
- Division of Haematology and Central Haematology Laboratory, Lausanne University Hospital (CHUV) and Faculty of Biology & Medicine, University of Lausanne, Lausanne, Switzerland.
| | - Frederik Delodder
- Service of Intensive Care and Burn Unit, Lausanne University Hospital (CHUV) and Faculty of Biology & Medicine, University of Lausanne, Lausanne, Switzerland
| | - Mohamed Faouzi
- Institute of Social and Preventive Medicine (IUMSP), Faculty of Biology & Medicine, University of Lausanne, Lausanne, Switzerland.
| | - Mette M Berger
- Service of Intensive Care and Burn Unit, Lausanne University Hospital (CHUV) and Faculty of Biology & Medicine, University of Lausanne, Lausanne, Switzerland.
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9
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Coagulation factor abnormalities related to discordance between anti-factor Xa and activated partial thromboplastin time in patients supported with continuous-flow left ventricular assist devices. J Heart Lung Transplant 2016; 35:1311-1320. [DOI: 10.1016/j.healun.2016.09.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 09/07/2016] [Accepted: 09/16/2016] [Indexed: 11/20/2022] Open
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Abstract
Optimal management of anticoagulant therapy requires an understanding of the laboratory tests often employed to guide therapy. The activated partial thromboplastin time (aPTT) can detect abnormalities in the intrinsic and common clotting pathways. Despite numerous limitations in the aPTT test, it remains the gold standard for monitoring unfractionated heparin and direct thrombin inhibitor therapy. The aPTT can be performed in the central laboratory or at the bedside (point of care [POC] testing). The activated clotting time (ACT) is a POC test that is routinely employed to monitor high-dose heparin during invasive and surgical procedures. The ACT therapeutic range will depend on the specific procedure or surgery being performed. Heparin levels are becoming more routinely available and are used to establish the aPTT therapeutic range for heparin therapy as well as for direct monitoring of heparin and low-molecular-weight heparin therapy. The international normalized ratio (INR) is the gold standard for monitoring warfarin patients. The target INR depends on the indication for anticoagulation. POC monitoring for warfarin is becoming increasingly used. Clinicians should have a thorough understanding of the benefits as well as the limitations of warfarin POC monitoring.
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Affiliation(s)
- Maureen A. Smythe
- William Beaumont Hospital, Royal Oak, Michigan, Department of Pharmacy Practice, Wayne State University, Detroit, Michigan,
| | - Anne Caffee
- Shenandoah University, Winchester, Virginia, Martinsburg Veterans Affairs Medical Center, Martinsburg, West Virginia
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Mischke R. Heparin in Vitro Sensitivity of the Activated Partial Thromboplastin Time in Canine Plasma Depends on Reagent. J Vet Diagn Invest 2016; 15:588-91. [PMID: 14667026 DOI: 10.1177/104063870301500615] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The in vitro heparin sensitivity of 6 different commercial activated partial thromboplastin time (APTT) reagents was investigated based on artificial plasma samples prepared by addition of sodium heparin at different activities (0—1.5 IU/ml) to pooled normal canine plasma. Statistical analysis using 2-way analysis of variance was based on APTT ratios (APTT/mean APTT control). Significant differences between the APTT ratios of different APTT reagents ( P < 0.00001) were found, which also depended on heparin activity (interaction between the factors; P < 0.00001). For example, mean APTT ratio at 0.7 IU/ml heparin varied between 1.2 and 2.5. The results of this study indicate that recommendations for the control of heparin therapy in dogs by APTT ratio should be reagent specific.
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Affiliation(s)
- Reinhard Mischke
- Clinic for Small Animals, School of Veterinary Medicine Hannover, Bischofsholer Damm 15, D-30173 Hannover, Germany
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12
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Yie K, Chon SHD, Na CY. Activated clotting time test alone is inadequate to optimize therapeutic heparin dosage adjustment during post-cardiopulmonary resuscitational extracorporeal membrane oxygenation (e-CPR). Perfusion 2015; 31:307-15. [PMID: 26354740 DOI: 10.1177/0267659115604710] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND We conducted an observational study to evaluate the relationship between activated clotting time (ACT) and activated partial thromboplastin time (aPTT) tests, anticipating the possibility that the ACT will become a substitute test for the aPTT in post-CPR extracorporeal membrane oxygenation (e-CPR). PATIENTS AND METHODS Three hundred and fifteen paired ACT and aPTT samples were derived from 60 in-hospital e-CPR patients and were divided into three groups according to the observed ACT value: low level (ACT < 170 s, Group A), intended target level (ACT 170-210 s Group B) and high level (ACT > 210 s, Group C). The relationship of aPTT in each group was analyzed. RESULTS The mean ACT and aPTT values were 189.39 ± 48.27 s (IQR, 163-202) and 71.85 ± 45.32 s (IQR, 44.5-81.8), respectively. Although the observed mean ACT value of 189.39 s was similar to the intended mean target value of 190 s (p = 0.823), the observed mean aPTT value (71.85 s) was significantly lower than the predicted mean target value (77.5 s, p = 0.027). Despite the mean ACT values being significantly different in each group (p < 0.0001), the mean aPTT values were not statistically different between Groups A and B (p = 0.317). Of the Group B samples (n = 139), only 31 samples (22.3%) met the optimal therapeutic aPTT range. Pearson's correlation coefficient for Group B showed only a weak correlation between ACT and aPTT (r = 0.177; p = 0.037). CONCLUSIONS Our study demonstrates that the ACT test alone does not seem to be enough to optimize therapeutic heparin dosage adjustment during e-CPR.
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Affiliation(s)
- Kilsoo Yie
- Department of Thoracic and Cardiovascular Surgery, Cheju Halla General Hospital, Jeju, S. Korea
| | - Soon-Ho Daniel Chon
- Department of Thoracic and Cardiovascular Surgery, Cheju Halla General Hospital, Jeju, S. Korea
| | - Chan-Young Na
- Department of Thoracic and Cardiovascular Surgery, Keimyung University, College of Medicine, Daegu, S.Korea
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13
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Kitchen S, Gray E, Mackie I, Baglin T, Makris M. Measurement of non-Coumarin anticoagulants and their effects on tests of Haemostasis: Guidance from the British Committee for Standards in Haematology. Br J Haematol 2014; 166:830-41. [DOI: 10.1111/bjh.12975] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Steve Kitchen
- Sheffield Haemophilia and Thrombosis Centre; Sheffield Teaching Hospitals NHS Trust; Sheffield UK
| | - Elaine Gray
- Haemostasis section; Biotherapeutics Group; National Institute for Biological Standards and Control; Potters Bar UK
| | - Ian Mackie
- Haemostasis Research Unit; Department of Haematology; University College London; London UK
| | - Trevor Baglin
- Department of Haematology; Addenbrooke's Hospital; Cambridge UK
| | - Mike Makris
- Sheffield Haemophilia and Thrombosis Centre; Sheffield Teaching Hospitals NHS Trust; Sheffield UK
- Department of Cardiovascular Science; University of Sheffield; Sheffield UK
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14
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Takemoto CM, Streiff MB, Shermock KM, Kraus PS, Chen J, Jani J, Kickler T. Activated partial thromboplastin time and anti-xa measurements in heparin monitoring: biochemical basis for discordance. Am J Clin Pathol 2013; 139:450-6. [PMID: 23525615 DOI: 10.1309/ajcps6ow6dynognh] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
We examined the concordance of heparin levels measured by a chromogenic anti-Xa assay and the activated partial thromboplastin time (APTT) during unfractionated heparin therapy (UFH) and the biochemical basis for differences between these measures. We also investigated the endogenous thrombin potential (ETP) as a possible measure of anticoagulation. Paired measures of anti-Xa and APTT were performed on 569 samples from 149 patients on UFH. The anti-Xa values and the APTT were concordant in only 54% of measurements. One hundred twelve samples from 59 patients on UFH were assayed for APTT, anti-Xa, factor II, factor VIII, and ETP. Supratherapeutic APTT values but therapeutic anti-Xa results had decreased factor II activity. Subtherapeutic APTT but therapeutic anti-Xa values had high factor VIII activity. ETP correlated with anticoagulation status and UFH dose. In conclusion, factor II and VIII activity contributes to discordance between APTT and anti-Xa results. ETP measurements may provide an additional assessment of anticoagulation status.
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Affiliation(s)
- Clifford M. Takemoto
- Department of Pediatric Hematology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Michael B. Streiff
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Kenneth M. Shermock
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
- Department of Pharmacy, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Peggy S. Kraus
- Department of Pharmacy, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Junnan Chen
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jayesh Jani
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Thomas Kickler
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
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15
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Price EA, Jin J, Nguyen HM, Krishnan G, Bowen R, Zehnder JL. Discordant aPTT and Anti-Xa Values and Outcomes in Hospitalized Patients Treated with Intravenous Unfractionated Heparin. Ann Pharmacother 2013; 47:151-8. [DOI: 10.1345/aph.1r635] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND: Both the activated partial thromboplastin time (aPTT) and anti-Xa assay can be used to monitor unfractionated heparin (UFH). Following implementation of an anti-Xa method for heparin dosing protocols in our hospital, we became aware of many patients with discordant aPTT and anti-Xa values. OBJECTIVE: To determine the frequency of discordant aPTT and anti-Xa values in a large cohort of hospitalized patients treated with UFH, as well as the demographics, coagulation status, indication for UFH, and clinical outcomes in this population. METHODS: All aPTT and anti-Xa values from adults hospitalized between February and August 2009 at Stanford Hospital who were treated with UFH were analyzed. All samples were drawn simultaneously. A polynomial fit correlating aPTT and anti-Xa with a 99% confidence limit was designed. Paired aPTT/anti-Xa values were grouped according to whether the paired values fell within or outside of the concordant area. Patients were placed into groups based on concordance status, and clinical outcomes were assessed. RESULTS: A total of 2321 paired values from 539 patients were studied; 42% of data pairs had a high aPTT value relative to the anti-Xa value. Patients with elevated baseline prothrombin time/international normalized ratio or aPTT frequently demonstrated disproportionate relative prolongation of the aPTT. Patients with at least 2 consecutive high aPTT to anti-Xa values had increased 21-day major bleeding (9% vs 3%; p = 0.0316) and 30-day mortality (14% dead vs 5% dead at 30 days; p = 0.0202) compared with patients with consistently concordant values. CONCLUSIONS: aPTT and anti-Xa values are frequently discordant when used to measure UFH in hospitalized patients. A disproportionate prolongation of the aPTT relative to the anti-Xa was the most common discordant pattern in our study. Patients with relatively high aPTT to anti-Xa values appear to be at increased risk of adverse outcomes. Monitoring both aPTT and Xa values may have utility in managing such patients.
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Affiliation(s)
- Elizabeth A Price
- Elizabeth A Price MD MPH, Clinical Affiliate, Department of Medicine (Hematology), School of Medicine, Stanford University, Stanford CA
| | - Jing Jin
- Jing Jin MD, Clinical Laboratory Scientist, Department of Pathology, School of Medicine, Stanford University
| | - Huong Marie Nguyen
- Huong (Marie) Nguyen MD, Hematology Fellow, Department of Medicine (Hematology), School of Medicine, Stanford University; Stanford Hospital and Clinics
| | - Gomathi Krishnan
- Gomathi Krishnan PhD, Clinical and Translational Research Informatics Specialist, Stanford Center for Clinical Informatics
| | - Raffick Bowen
- Raffick Bowen PhD, Assistant Professor, Department of Pathology, Stanford University
| | - James L Zehnder
- James L Zehnder MD, Professor of Pathology and Medicine (Hematology), Department of Pathology, School of Medicine, Stanford University
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Marlar RA, Gausman J. The Optimum Number and Types of Plasma Samples Necessary for an Accurate Activated Partial Thromboplastin Time–Based Heparin Therapeutic Range. Arch Pathol Lab Med 2013; 137:77-82. [DOI: 10.5858/arpa.2011-0516-oa] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
Context.—Monitoring of unfractionated heparin therapy by activated partial thromboplastin time (aPTT) using the ex vivo method for determining the aPTT-based heparin therapeutic range (HTR) is the standard of practice. Many intrinsic and extrinsic factors influence its accuracy.
Objective.—To investigate the optimum number and types of samples acceptable for an accurate ex vivo HTR determination.
Design.—Values from patients receiving unfractionated heparin are used to determine the HTR by published guidelines. The number and types of samples are changed to investigate the effect on HTR parameters.
Results.—Absolute minimum number of samples for an accurate HTR is 20, with fewer than 10% of the samples from the same patient or 50% of the samples with international normalized ratio of 1.3 to 1.5.
Conclusions.—The ex vivo HTR method is the best protocol currently available; however, the number of samples used affects its accuracy. The optimum number of samples is 30 or more but the absolute minimum number is 20. In addition, limitation of specific sample types also affects the HTR parameters. An inaccurate HTR may be calculated if inappropriate sample number or types of samples are used.
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Affiliation(s)
- Richard A. Marlar
- From Pathology and Laboratory Medicine Services, Oklahoma City VA Medical Center, Oklahoma City, Oklahoma (Dr Marlar and Ms Gausman); and the Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City (Dr Marlar)
| | - Jana Gausman
- From Pathology and Laboratory Medicine Services, Oklahoma City VA Medical Center, Oklahoma City, Oklahoma (Dr Marlar and Ms Gausman); and the Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City (Dr Marlar)
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Evaluation of the Q analyzer, a new cap-piercing fully automated coagulometer with clotting, chromogenic, and immunoturbidometric capability. Blood Coagul Fibrinolysis 2012; 24:28-34. [PMID: 23249565 DOI: 10.1097/mbc.0b013e3283597621] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The Q analyzer is a recently launched fully automated photo-optical analyzer equipped with primary tube cap-piercing and capable of clotting, chromogenic, and immunoturbidometric tests. The purpose of the present study was to evaluate the performance characteristics of the Q analyzer with reagents from the instrument manufacturer. We assessed precision and throughput when performing coagulation screening tests, prothrombin time (PT)/international normalized ratio (INR), activated partial thromboplastin time (APTT), and fibrinogen assay by Clauss assay. We compared results with established reagent instrument combinations in widespread use. Precision of PT/INR and APTT was acceptable as indicated by total precision of around 3%. The time to first result was 3 min for an INR and 5 min for PT/APTT. The system produced 115 completed samples per hour when processing only INRs and 60 samples (120 results) per hour for PT/APTT combined. The sensitivity of the DG-APTT Synth/Q method to mild deficiency of factor VIII (FVIII), IX, and XI was excellent (as indicated by APTTs being prolonged above the upper limit of the reference range). The Q analyzer was associated with high precision, acceptable throughput, and good reliability. When used in combination with DG-PT reagent and manufacturer's instrument-specific international sensitivity index, the INRs obtained were accurate. The Q analyzer with DG-APTT Synth reagent demonstrated good sensitivity to isolated mild deficiency of FVIII, IX, and XI and had the advantage of relative insensitivity to mild FXII deficiency. Taken together, our data indicate that the Q hemostasis analyzer was suitable for routine use in combination with the reagents evaluated.
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18
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Marlar RA, Gausman JN. The effect of instrumentation and laboratory site on the accuracy of the APTT-based heparin therapeutic range. Int J Lab Hematol 2012; 34:614-20. [DOI: 10.1111/j.1751-553x.2012.01445.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 04/23/2012] [Indexed: 11/30/2022]
Affiliation(s)
- R. A. Marlar
- Pathology and Laboratory Medicine Services; Oklahoma City VA Medical Center; Oklahoma City OK USA
- Department of Pathology; University of Oklahoma Health Sciences Center; Oklahoma City OK USA
| | - J. N. Gausman
- Pathology and Laboratory Medicine Services; Oklahoma City VA Medical Center; Oklahoma City OK USA
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19
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Gouin-Thibaut I, Martin-Toutain I, Peynaud-Debayle E, Marion S, Napol P, Alhenc-Gelas M. Monitoring unfractionated heparin with APTT: A French collaborative study comparing sensitivity to heparin of 15 APTT reagents. Thromb Res 2012; 129:666-7. [DOI: 10.1016/j.thromres.2011.11.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 11/09/2011] [Accepted: 11/09/2011] [Indexed: 11/29/2022]
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20
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Zehnder J, Price E, Jin J. Controversies in heparin monitoring. Am J Hematol 2012; 87 Suppl 1:S137-40. [PMID: 22495972 DOI: 10.1002/ajh.23210] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 03/07/2012] [Accepted: 03/07/2012] [Indexed: 11/09/2022]
Affiliation(s)
- James Zehnder
- Departments of Pathology and Medicine, Hematology, Stanford University School of Medicine, California 94305, USA.
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21
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Vandiver JW, Vondracek TG. Antifactor Xa levels versus activated partial thromboplastin time for monitoring unfractionated heparin. Pharmacotherapy 2012; 32:546-58. [PMID: 22531940 DOI: 10.1002/j.1875-9114.2011.01049.x] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Intravenous unfractionated heparin (UFH) remains an important therapeutic agent, particularly in the inpatient setting, for anticoagulation. Historically, the activated partial thromboplastin time (aPTT) has been the primary laboratory test used to monitor and adjust UFH. The aPTT test has evolved since the 1950s, and the historical goal range of 1.5-2.5 times the control aPTT, which first gained favor in the 1970s, has fallen out of favor due to a high degree of variability in aPTT readings from one laboratory to another, and even from one reagent to another. As a result, it is now recommended that the aPTT goal range be based on a corresponding heparin concentration of 0.2-0.4 unit/ml by protamine titration or 0.3-0.7 unit/ml by antifactor Xa assay. Given that several biologic factors can influence the aPTT independent of the effects of UFH, many institutions have transitioned to monitoring heparin with antifactor Xa levels, rather than the aPTT. Clinical data from the last 10-20 years have begun to show that a conversion from aPTT to antifactor Xa monitoring may offer a smoother dose-response curve, such that levels remain more stable, requiring fewer blood samples and dosage adjustments. Given the minimal increased acquisition cost of the antifactor Xa reagents, it can be argued that the antifactor Xa is a cost-effective method for monitoring UFH. In this review, we discuss the relative advantages and disadvantages of the aPTT, antifactor Xa, and protamine titration tests, and provide a clinical framework to guide practitioners who are seeking to optimize UFH monitoring within their own institutions.
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Affiliation(s)
- Jeremy W Vandiver
- Department of Pharmacy, Exempla Saint Joseph Hospital, 1835 Franklin Street, Denver, CO 80218, USA
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22
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Gausman JN, Marlar RA. Inaccuracy of a "spiked curve" for monitoring unfractionated heparin therapy. Am J Clin Pathol 2011; 135:870-6. [PMID: 21571960 DOI: 10.1309/ajcp60zgxcjkrmjo] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Our purpose was to determine whether the in vitro (or "spiked curve") method for the therapeutic heparin range is an accurate and valid method for heparin monitoring. Many laboratories use the in vitro method for determining the activated partial thromboplastin time (APTT)-based unfractionated heparin (UFH) therapeutic range as a more practical method to determine the therapeutic heparin range. Is this a valid method compared with the recommended ex vivo method? Plasma samples from patients receiving UFH and a normal plasma pool spiked with UFH were compared for 8 APTT reagents (18 lots). The in vitro curve has significantly increased lower limit and upper limit values and has a significantly widened range compared with the ex vivo method. When APTT values are compared with both methods, more samples are underheparinized with the in vitro curve method. The in vitro method is not a valid method to determine an accurate therapeutic heparin range.
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23
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Newall F, Ignjatovic V, Johnston L, Summerhayes R, Lane G, Cranswick N, Monagle P. research paper: Clinical use of unfractionated heparin therapy in children: time for change? Br J Haematol 2010; 150:674-8. [DOI: 10.1111/j.1365-2141.2010.08302.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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24
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CUKER A, CINES DB, POLLAK ES. Interlaboratory agreement in the monitoring of unfractionated heparin using the anti-factor Xa-correlated activated partial thromboplastin time: reply to a rebuttal. J Thromb Haemost 2009. [DOI: 10.1111/j.1538-7836.2009.03625.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Kitchen S, Preston FE, Jennings I, Kitchen DP, Woods TAL, Walker I. Interlaboratory agreement in the monitoring of unfractionated heparin using the anti-factor Xa-correlated activated partial thromboplastin time: a rebuttal. J Thromb Haemost 2009; 7:2157-8; author reply 2178-9. [PMID: 19765209 DOI: 10.1111/j.1538-7836.2009.03616.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Breuhl EL, Moore G, Brooks MB, Scott-Moncrieff JC. A prospective study of unfractionated heparin therapy in dogs with primary immune-mediated hemolytic anemia. J Am Anim Hosp Assoc 2009; 45:125-33. [PMID: 19411648 DOI: 10.5326/0450125] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Unfractionated heparin therapy was initiated at a standard dosage of 300 IU/kg subcutaneously q 6 hours to 18 dogs with immune-mediated hemolytic anemia. Heparin's prolongation of activated partial thromboplastin time and change in factor Xa inhibition (anti-Xa activity) were serially monitored during the first 40 hours of therapy. During the initial 40 hours, only eight of 18 dogs had attained anti-Xa activities of > or =0.35 U/mL. No dogs had clinical signs of hemorrhage. Fifteen dogs survived to discharge; 11 dogs were alive at 1 year, and thrombosis was identified in three of six nonsurvivors that were necropsied.
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Affiliation(s)
- Elizabeth L Breuhl
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Lynn Hall, Purdue University, West Lafayette, Indiana 47907, USA
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27
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Cuker A, Ptashkin B, Konkle BA, Pipe SW, Whinna HC, Zheng XL, Cines DB, Pollak ES. Interlaboratory agreement in the monitoring of unfractionated heparin using the anti-factor Xa-correlated activated partial thromboplastin time. J Thromb Haemost 2009; 7:80-6. [PMID: 19017257 DOI: 10.1111/j.1538-7836.2008.03224.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND In an effort to improve interlaboratory agreement in the monitoring of unfractionated heparin (UFH), the College of American Pathologists (CAP) recommends that the therapeutic range of the activated partial thromboplastin time (APTT) be defined in each laboratory through correlation with a direct measure of heparin activity such as the factor Xa inhibition assay. Whether and to what extent this approach enhances the interlaboratory agreement of UFH monitoring has not been reported. OBJECTIVES We conducted a cross-validation study among four CAP-accredited coagulation laboratories to compare the interlaboratory agreement of the anti-FXa-correlated APTT with that of the traditional 1.5-2.5 times the midpoint of normal (1.5-2.5:control) method for defining the therapeutic APTT range. PATIENTS AND METHODS APTT and FXa inhibition assays were performed in each laboratory on plasma samples from 44 inpatients receiving UFH. RESULTS Using the anti-FXa-correlation method, there was agreement among all four laboratories as to whether a sample was subtherapeutic, therapeutic or supratherapeutic in seven (16%) patient samples. In contrast, consensus was achieved in 23 (52%) samples when the 1.5-2.5:control method was employed. CONCLUSIONS The anti-FXa-correlation method does not appear to enhance interlaboratory agreement in UFH monitoring as compared with the traditional 1.5-2.5:control method. Adoption of the anti-FXa-correlation method produces considerable disparity in UFH dosing decisions among different centers, although the clinical impact of this disparity is not known.
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Affiliation(s)
- A Cuker
- Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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28
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Lehman CM, Frank EL. Laboratory Monitoring of Heparin Therapy: Partial Thromboplastin Time or Anti-Xa Assay? Lab Med 2009. [DOI: 10.1309/lm9njgw2ziolphy6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Francis JL, Hursting MJ. Effect of argatroban on the activated partial thromboplastin time: a comparison of 21 commercial reagents. Blood Coagul Fibrinolysis 2005; 16:251-7. [PMID: 15870544 DOI: 10.1097/01.mbc.0000169217.15926.d0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Argatroban is a direct thrombin inhibitor used for the treatment of heparin-induced thrombocytopenia. The drug is administered by continuous infusion, at a recommended initial dose of 2 microg/kg per min, to achieve activated partial thromboplastin times (aPTTs) 1.5-3.0 times baseline. We evaluated the effect of argatroban, at clinically relevant concentrations, on aPTTs using 21 commercially available reagents. The aPTTs of plasma containing argatroban at 0.125-8.0 microg/ml (final concentration) were assessed using each reagent and an ACL 3000+ coagulation analyzer. Argatroban increased aPTTs (and aPTT ratios relative to control) in a broadly comparable fashion among reagents. Concentration-aPTT ratio profiles linearized well using logarithmic-logarithmic transformation (r > 0.98), with the regression slope taken as the reagent's sensitivity to argatroban. Sensitivity ranged from 0.304 +/- 0.006 to 0.364 +/- 0.007. Only the least and two most sensitive reagents (all now unavailable in the United States) differed significantly in sensitivity from the other reagents (P < 0.05). aPTT ratios of 2.25 occurred for all reagents at 0.41-0.92 mug/ml argatroban, and for 14 (67%) reagents at 0.53-0.67 microg/ml. This corresponds to a approximately 0.5 microg/kg per min dose difference in healthy subjects. We conclude that most aPTT reagents are similarly sensitive to argatroban, and reagent choice is unlikely to significantly affect argatroban monitoring in patients with heparin-induced thrombocytopenia.
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Affiliation(s)
- John L Francis
- Florida Hospital Center for Thrombosis and Hemostasis, 2501 North Orange Avenue, Orlando, FL 32804, USA.
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30
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Abstract
BACKGROUND Ecarin Clotting Time (ECT) assay specifically determines the inhibition of meizothrombin by direct thrombin inhibitors (DTI). Blood coagulation factor levels lowered by vitamin K antagonists (VKA) may prolong ECT. Concomitant treatment of VKA with DTI may influence differently the two published ECT methods. METHODS Lepirudin (100-3,000 ng/ml), argatroban (300--3,000 ng/ml) and melagatran (30--1000 ng/ml) were added to normal plasma (NP; n=12) samples and to plasma of patients on stable vitamin K antagonist therapy with warfarin (VKAP; n=12). ECT assays were performed according to [5] (method 1) and according to [6] (method 2). Data were subjected to multifactorial variance analysis. RESULTS Normal ranges were 35.5+/-2.8 s in NP versus 31.8+/-1.2 s in VKAP with method 1 (p< 0.001) and 44.3+/-3.9 s in NP vs. 51.4+/-8.3 s in VKAP with method 2 (p< 0.004). Besides the inhibitors (p<0.0001), the method used (p<0.0001) and the group (NP vs. VKAP, p=0.003) had an influence on the ECT. Inhibitors (p< 0.02) or method used (p< 0.03) and the group (NP vs. VKAP, p=0.0001) influenced also the ECT ratio. DISCUSSION Both ECT methods are suitable for monitoring different DTIs over a large linear range with both methods during concomitant treatments with vitamin K antagonists. The ECT ratio improves but not abolishes the differences between the methods. Additive effects of vitamin K antagonists on ECT methods have to be taken into consideration in clinical routine.
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Affiliation(s)
- Tivadar Fenyvesi
- IV. Department of Medicine, University Hospital Mannheim, Theodor-Kutzer-Ufer 1-3, D-68167 Mannheim, Germany.
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Spinler SA, Wittkowsky AK, Nutescu EA, Smythe MA. Anticoagulation Monitoring Part 2: Unfractionated Heparin and Low-Molecular-Weight Heparin. Ann Pharmacother 2005; 39:1275-85. [PMID: 15956240 DOI: 10.1345/aph.1e524] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To review the availability, mechanisms, limitations, and clinical application of point-of-care (POC) devices used in monitoring anticoagulation with unfractionated heparin (UFH) and low-molecular-weight heparins (LMWHs). DATA SOURCES Articles were identified through a MEDLINE search (1966–August 2004), device manufacturer Web sites, additional references listed in articles and Web sites, and abstracts from scientific meetings. STUDY SELECTION AND DATA EXTRACTION English-language literature from clinical trials was reviewed to evaluate the accuracy, reliability, and clinical application of POC monitoring devices. DATA SYNTHESIS The activated partial thromboplastin time (aPTT) and activated clotting time (ACT) are common tests for monitoring anticoagulation with UFH. Multiple devices are available for POC aPTT, ACT, and heparin concentration testing. The aPTT therapeutic range for UFH will vary depending upon the reagent and instrument employed. Although recommended by the American College of Chest Physicians Seventh Conference on Antithrombotic and Thrombolytic Therapy, establishing a heparin concentration–derived therapeutic range for UFH is rarely performed. Additional research evaluating anti-factor Xa monitoring of LMWHs using POC testing is necessary. CONCLUSIONS Multiple POC devices are available to monitor anticoagulation with UFH. For each test, there is some variability in results between devices and between reagents used in the same device. Despite these limitations, POC anticoagulation monitoring of UFH using aPTT and, more often, ACT is common in clinical practice, particularly when evaluating anticoagulation associated with interventional cardiology procedures and cardiopulmonary bypass surgery.
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Affiliation(s)
- Sarah A Spinler
- Cardiovascular Division, Department of Medicine, Philadelphia College of Pharmacy, University of Pennsylvania, Philadelphia, PA, USA.
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McGlasson DL, Kaczor DA, Krasuski RA, Campbell CL, Kostur MR, Adinaro JT. Effects of pre-analytical variables on the anti-activated factor X chromogenic assay when monitoring unfractionated heparin and low molecular weight heparin anticoagulation. Blood Coagul Fibrinolysis 2005; 16:173-6. [PMID: 15795534 DOI: 10.1097/01.mbc.0000164424.90545.6e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The purpose of this study was to determine whether the anti-activated factor X (anti-FXa) assay is less affected by pre-analytical variables in monitoring patients on unfractionated heparin (UFH) and low molecular weight heparin (LMWH) than the activated partial thromboplastin time (aPTT). Forty-six subjects receiving either enoxaparin (LMWH) or UFH were randomly selected. Each study subject had six vacutainer tubes (3.8% sodium citrate, 3.2% sodium citrate) drawn by an atraumatic venipuncture. One tube from each set had a blood to anticoagulant ratio of 9: 1. The other tube had an intentional "short-draw" of approximately 6: 1 blood to anticoagulant ratio. All specimens had an aPTT and a chromogenic anti-FXa assay performed on each specimen regardless of heparin type. The aPTT assay mean with the 3.8% sodium citrate tube short-draw tube was statistically different from the other aPTT assays (P = 0.06). However, all six of the mean anti-FXa assays for the UFH and LMWH heparin subjects were not statistically or clinically different (analysis of variance, P = 0.9878 for UFH and P = 0.9060 for LMWH). The intentional short-draw tube did not affect the anti-FXa assay regardless of the anticoagulant. The anti-FXa assay appears to be a better method for monitoring heparin subjects than the aPTT due to the lack of effect of pre-analytical variables.
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Affiliation(s)
- David L McGlasson
- 59th Clinical Research Squadron, Wilford Hall Medical Center, 2200 Berquist Drive, Lackland AFB, TX 78236-5300, USA. david.mcglasson@lackland af.mil
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Brooks MB. Evaluation of a chromogenic assay to measure the factor Xa inhibitory activity of unfractionated heparin in canine plasma. Vet Clin Pathol 2005; 33:208-14. [PMID: 15570557 DOI: 10.1111/j.1939-165x.2004.tb00375.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Unfractionated heparin (UFH) has a complex pharmacologic profile that necessitates patient monitoring to prevent inadequate anticoagulation or overdosage and hemorrhage. Factor Xa inhibitory assays (to measure anti-Xa activity) are used to adjust UFH dosage and define safe and effective regimens for specific thrombotic disorders in humans. OBJECTIVE In this study, the accuracy, linearity, and clinical utility of a chromogenic assay were assessed for monitoring UFH anti-Xa activity in canine plasma samples. METHODS A commercial assay (Rotachrom Heparin, Diagnostica Stago, Parsippany, NJ, USA) was used to measure anti-Xa activity in canine plasma samples spiked with different concentrations of UFH. Background absorbance and assay linearity were compared for canine and human plasmas. Percentage recovery of UFH anti-Xa activity and intra- and interassay imprecisions were investigated by multiple measurements of canine plasma to which known amounts of UFH were added. The spiked plasma samples also were used to determine the heparin sensitivity of an activated partial thromboplastin time (aPTT) test. RESULTS Canine plasma samples were assayed at a higher dilution than were human plasma samples (3:8 versus 4:8) to eliminate higher background anti-Xa activity in canine plasma. Using this modification, the recovery of anti-Xa activity in canine plasma was linear (R2 > .9) at concentrations of 0 - 0.75 U/mL UFH. Intra- and interassay imprecisions for plasma samples containing 0.5 U/mL UFH were <10%, whereas samples containing 0.25 U/mL UFH had imprecisions of 13% and 24%, respectively. The anti-Xa activity range of 0.5 - 0.75 U/mL caused prolongation of aPTTs to 1.5 - 2.5 times the assay mean. CONCLUSION Plasma anti-Xa activity of dogs treated with UFH can be accurately monitored using this commercially available chromogenic assay.
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Affiliation(s)
- Marjory B Brooks
- Comparative Coagulation Section, Animal Health Diagnostic Laboratory, Cornell University, Ithaca, NY 14850, USA.
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Dreier JP, Lurtzing F, Kappmeier M, Bohner G, Klingebiel R, Leistner S, Einhaupl KM, Schielke E, Valdueza JM. Delayed Occlusion after Internal Carotid Artery Dissection under Heparin. Cerebrovasc Dis 2004; 18:296-303. [PMID: 15331876 DOI: 10.1159/000080355] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2003] [Accepted: 04/07/2004] [Indexed: 11/19/2022] Open
Abstract
Internal carotid artery dissection (ICAD) is a frequent etiology of stroke in the young. Immediate anticoagulation with unfractionated heparin is the most frequent treatment. A theoretical side effect of unfractionated heparin is an increase in the intramural hematoma resulting in hemodynamic cerebral infarction. We studied 20 patients with ICAD. All patients were immediately treated with unfractionated heparin. Activated partial thromboplastin time (aPTT) ratios were measured twice daily. We prospectively monitored the course of ICAD with repeated ultrasound in hospital. Unexpectedly, delayed ICA occlusion was noted in 5 patients under treatment. One of these developed a watershed infarct. We then analyzed the aPTT ratios over the first 6 days after diagnosis. Patients with delayed occlusion had significantly higher aPTT ratios (2.6 +/- 0.4 vs. 2.0 +/- 0.5, p < 0.05). Within the limits of a partially retrospective design, our study seems to support the notion that unfractionated heparin can increase the intramural hematoma. Our findings further justify a randomized clinical trial to resolve the anticoagulant/antiplatelet debate.
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Affiliation(s)
- Jens P Dreier
- Department of Neurology, Campus Mitte, Charité University of Medicine Berlin, Berlin, Germany.
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Thompson MF, Scott-Moncrieff JC, Brooks MB. Effect of a Single Plasma Transfusion on Thromboembolism in 13 Dogs With Primary Immune-Mediated Hemolytic Anemia. J Am Anim Hosp Assoc 2004; 40:446-54. [PMID: 15533964 DOI: 10.5326/0400446] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Thirteen dogs with primary immune-mediated hemolytic anemia received fresh-frozen plasma within 12 hours of admission, in addition to unfractionated heparin and other therapies, such as prednisone, azathioprine, and packed red blood cell transfusion. Antithrombin activity was quantified prior to transfusion and at 30 minutes and 48 hours after transfusion. Plasma antithrombin activity did not change significantly after a single plasma transfusion. There were no deaths in the first 48 hours of treatment. Thromboembolism was identified at necropsy in six of 10 dogs that died within 12 months of admission. There was no significant difference in the incidence of thromboembolism between the current treatment group and a historical control group.
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Affiliation(s)
- Mary F Thompson
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, Indiana 47907, USA
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Effects of vitamin K antagonist phenprocoumon on activated partial thromboplastin time measurement of direct thrombin inhibitors. Blood Coagul Fibrinolysis 2004. [DOI: 10.1097/00001721-200409000-00012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Fenyvesi T, Jörg I, Weiss C, Harenberg J. Effects of vitamin K antagonist phenprocoumon on activated partial thromboplastin time measurement of direct thrombin inhibitors. Blood Coagul Fibrinolysis 2004; 15:605-11. [PMID: 15389129 DOI: 10.1097/00001721-200410000-00012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The activated partial thromboplastin time (aPTT) is currently the most common test used to measure the anticoagulation intensity of heparins and direct thrombin inhibitors (DTIs). Vitamin K antagonists variably affect aPTT reagents. Interactions between heparin and DTIs occur during concurrent therapy. Three DTIs (lepirudin, argatroban, melagatran) and one unfractionated heparin (liquemin) were added to normal plasma (NP) samples (n = 23) and to vitamin K antagonist plasma (VKAP) samples (n = 23) of patients treated with phenprocoumon. Lepirudin and argatroban were added at concentrations from 300 to 3000 ng/ml, melagatran from 30 to 1000 ng/ml, and unfractionated heparin from 0.016 to 0.48 IU/ml. Wave parameters of clotting time and aPTT ratio curves were evaluated by multivariate analysis for inhibitors, aPTT reagents and NP and VKAP samples. Normal ranges resulting from NP samples were 34.5 +/- 1.0 s with Pathromtin SL and 33.9 +/- 0.8 s with Platelin LS. Normal ranges using VKAP were 52.8 +/- 2.6 s (Pathromtin SL) and 44.2 +/- 1.1 s (Platelin LS) (P < 0.0001). Variance analysis showed that inhibitors, plasmas (NP versus VKAP) and reagents influenced the wave characteristics of aPTT (s) (P < 0.0001) and aPTT ratios (P < 0.0001). Distinct statistical differences between aPTT reagents on one hand and normal versus vitamin K antagonist plasma on the other hand make a comparison of reported aPTT results difficult, especially during overlapping therapy with vitamin K antagonists.
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Affiliation(s)
- Tivadar Fenyvesi
- IV Department of Medicine, University Hospital Mannheim, Mannheim, Germany
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Abstract
This article about unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. UFH is a heterogeneous mixture of glycosaminoglycans that bind to antithrombin via a pentasaccharide, catalyzing the inactivation of thrombin and other clotting factors. UFH also binds endothelial cells, platelet factor 4, and platelets, leading to rather unpredictable pharmacokinetic and pharmacodynamic properties. Variability in activated partial thromboplastin time (aPTT) reagents necessitates site-specific validation of the aPTT therapeutic range in order to properly monitor UFH therapy. Lack of validation has been an oversight in many clinical trials comparing UFH to LMWH. In patients with apparent heparin resistance, anti-factor Xa monitoring may be superior to measurement of aPTT. LMWHs lack the nonspecific binding affinities of UFH, and, as a result, LMWH preparations have more predictable pharmacokinetic and pharmacodynamic properties. LMWHs have replaced UFH for most clinical indications for the following reasons: (1) these properties allow LMWHs to be administered subcutaneously, once daily without laboratory monitoring; and (2) the evidence from clinical trials that LMWH is as least as effective as and is safer than UFH. Several clinical issues regarding the use of LMWHs remain unanswered. These relate to the need for monitoring with an anti-factor Xa assay in patients with severe obesity or renal insufficiency. The therapeutic range for anti-factor Xa activity depends on the dosing interval. Anti-factor Xa monitoring is prudent when administering weight-based doses of LMWH to patients who weigh > 150 kg. It has been determined that UFH infusion is preferable to LMWH injection in patients with creatinine clearance of < 25 mL/min, until further data on therapeutic dosing of LMWHs in renal failure have been published. However, when administered in low doses prophylactically, LMWH is safe for therapy in patients with renal failure. Protamine may help to reverse bleeding related to LWMH, although anti-factor Xa activity is not fully normalized by protamine. The synthetic pentasaccharide fondaparinux is a promising new antithrombotic agent for the prevention and treatment of venous thromboembolism.
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Affiliation(s)
- Jack Hirsh
- Henderson Research Centre, 711 Concession St, Hamilton, ON L8V 1C3, Canada.
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Abstract
Unfractionated heparin (UFH) has been in clinical use for more than half a century. Despite its undoubted contribution to the treatment and prevention of thrombosis, heparin is significantly limited by its variable biochemical composition and unpredictable pharmacokinetics. The situation is compounded by the fact that methods for monitoring heparin do not necessarily reflect its therapeutic effect. The activated partial thromboplastin time (aPTT) is a method for monitoring heparin therapy that is simple, cheap, and readily available. However, it is also poorly standardized and is affected by numerous factors-both analytic and preanalytic-that are unrelated to the heparin effect. Establishing an appropriate therapeutic range for the aPTT is challenging for smaller clinical laboratories, and the antifactor Xa method of measuring heparin levels is not widely available. The College of American Pathologists published consensus guidelines in an effort to improve the laboratory monitoring of UFH therapy. However, it seems unlikely that the laboratory problems associated with monitoring UFH will be resolved. Unfractionated heparin is highly antigenic and carries a significant risk of heparin-induced thrombocytopenia (HIT). Even in the absence of thrombocytopenia or thrombosis, the presence of heparin-associated antibodies may predict adverse clinical outcomes and strengthen the rationale for the ultimate replacement of UFH. Fortunately, alternatives to UFH, such as low-molecular-weight heparins, direct thrombin inhibitors, and more specific factor Xa inhibitors, are becoming available for clinical use. The pharmacokinetics of these agents are more predictable and rely much less on laboratory monitoring. Nonheparin agents also eliminate the risk of HIT. The emergence of these newer anticoagulants makes the continued use of UFH increasingly difficult to justify.
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Affiliation(s)
- John L Francis
- Florida Hospital Center for Hemostasis and Thrombosis, Orlando, Florida 32804, USA.
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Schumacker-Blay C, Fischer F, Appert A, Lallia A, Carlon M, Dellamonica J, Jambou D, Marabelle B, Bongain A. [Repeated thromboembolism during pregnancy with constitutional antithrombin deficiency]. ACTA ACUST UNITED AC 2004; 33:330-3. [PMID: 15170430 DOI: 10.1016/s0368-2315(04)96463-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We report the case of a twenty-three-year old woman with constitutional antithrombin deficiency, who had oral anticoagulation since she was four years old. During her first pregnancy, after the introduction of unfractionated heparin prophylactic therapy, she presented a first venous thromboembolism at nine weeks, and a second one with low-molecular-weight heparin therapy at nineteen weeks. Because of a severe antithombin deficiency, regular infusions of antithrombin concentrates were necessary until delivery to ensure effective anticoagulation by heparin. Patients with antithrombin deficiency have a very high risk of venous thromboses during the pregnancy and post-partum. We discuss the significant points of management for this period.
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Affiliation(s)
- C Schumacker-Blay
- Service de Gynécologie-Obstétrique-Reproduction et de Médecine Foetale, CHU de Nice-Sophia-Antipolis, Hôpital de l'Archet 2, Centre Femme-Mère-Enfant
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Fenyvesi T, Jörg I, Weiss C, Harenberg J. Effects of lepirudin, argatroban and melagatran and additional influence of phenprocoumon on ecarin clotting time. Thromb Res 2003; 111:89-94. [PMID: 14644085 DOI: 10.1016/j.thromres.2003.08.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Direct thrombin inhibitors (DTI) prolong the ecarin clotting time (ECT). Oral anticoagulants (OA) decrease prothrombin levels and thus interact with actions of DTIs on the ECT method during concomitant therapy. MATERIALS AND METHODS Actions of lepirudin, argatroban and melagatran on ECT were investigated in normal plasma (NP) and in plasma of patients (n=23 each) on stable therapy with phenprocoumon (OACP). Individual line characteristics were tested statistically. RESULTS Control ECT in OACP was prolonged compared to NP (50.1+/-0.9 vs. 45.7+/-0.8 s; p<0.001). Lepirudin prolonged the ECT linearly. Argatroban and melagatran delivered biphasic dose-response curves. OA showed additive effects on the ECT of lepirudin but not of argatroban and melagatran. Both in NP and OACP, the first and second slopes of melagatran were steeper compared to argatroban (primary analysis; p<0.001). When using the same drug, slopes in OACP were steeper than in NP (secondary analysis; p<0.001). At similar molar concentrations, the crossing points of both slopes were significantly higher with melagatran (323.1+/-11.0 s in NP and 333.2+/-8.2 s in OACP) than with argatroban (219.6+/-14.7 and 248.4+/-15.2 s) corresponding to ratios of 7.1+/-0.2 and 6.7+/-0.2 (melagatran) vs. 4.8+/-0.3 and 4.9+/-03 with argatroban (p<0.0001). DISCUSSION The patterns of interactions between vitamin K antagonists and DTI effects are different for bivalent (increase of slope without affecting linearity) and monovalent inhibitors (slight increase or alteration of nonlinear slopes), but there are also differences between the two monovalent inhibitors on thrombin inhibition as determined by ECT.
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Affiliation(s)
- Tivadar Fenyvesi
- Fourth Department of Medicine, University Hospital Mannheim, Theodor Kutzer Ufer 1-3, 68167 Mannheim, Germany.
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van den Besselaar AMHP, Sturk A, Reijnierse GLA. Monitoring of unfractionated heparin with the activated partial thromboplastin time: determination of therapeutic ranges. Thromb Res 2002; 107:235-40. [PMID: 12479884 DOI: 10.1016/s0049-3848(02)00303-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The purpose of the present study was to determine therapeutic ranges for unfractionated heparin therapy using the activated partial thromboplastin time (APTT) by calibration against anti-Xa concentration. APTT assays were performed locally, i.e. at the institution of blood collection, on fresh plasma samples from patients treated with intravenous unfractionated heparin. The measurements were performed by 25 Dutch clinical laboratories using 11 different APTT reagents and 10 different types of coagulometers. After the local APTT measurement, the samples were frozen and transported to a central laboratory for measurement of anti-Xa activity. The number of samples from the participating laboratories ranged from 10 to 48. Local APTT results were correlated with the central anti-Xa measurements. Orthogonal regression analysis of log-transformed values was used to calculate APTT therapeutic ranges corresponding to anti-Xa concentrations of 0.29-0.47 IU/ml. The calculated APTT ranges were different between laboratories, even when the same reagent was used. In many laboratories, the therapeutic APTT range in use was much wider than the calculated range. Imprecision of the calculated APTT range was influenced by the wide scatter of the measurement points and by the selection of samples for the orthogonal regression equation. The present results show that, if anti-Xa concentrations of 0.29-0.47 IU/ml reflect the true therapeutic range, many laboratories do not use the proper therapeutic APTT range.
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Affiliation(s)
- A M H P van den Besselaar
- Department of Hematology, Leiden University Medical Center, P O Box 9600, 2300 RC, Leiden, The Netherlands.
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Gaussem P, Dubar M, le Bonniec B, Richard-Lordereau I, Jochemsen R, Aiach M. Dose-effect relationship for several coagulation markers during administration of the direct thrombin inhibitor S 18326 in healthy subjects. Br J Clin Pharmacol 2002; 53:147-54. [PMID: 11851638 PMCID: PMC1874285 DOI: 10.1046/j.0306-5251.2001.01534.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS We conducted a phase I placebo-controlled trial with two i.v. doses (0.5 mg h-1 and 3 mg h-1) of S 18326, a selective thrombin inhibitor that interacts with the catalytic site of thrombin, with the aim to study the relationships between increasing plasma levels of S 18326 and changes in coagulation tests and thrombin generation markers. METHODS Thirty-six healthy male volunteers were divided into three groups. In each group, 10 volunteers were randomly assigned to receive S 18326 and two to receive a placebo. Following a bolus of 4.5 mg, doses were 0.5 mg h-1 in the first group and 3 mg h-1 in the two other groups, administered as an i.v. infusion for 24 h. Blood was drawn repeatedly up to 36 h after the bolus, and tested for the activated clotting time (ACT) and activated partial thromboplastin time (APTT). The APTT reagent was chosen among five commercial reagents to yield a linear increase in the clotting time among possible therapeutic S 18326 concentrations in vitro. To accurately measure the thrombin-inhibiting effects of low doses of S 18326 (< 0.5 microm), we developed a specific chromogenic assay. We also measured F1 + 2 prothrombin fragment levels to assess the effect of S 18326 on thrombin generation in vivo. RESULTS A two-compartment pharmacokinetic model was fitted to the S 18326 plasma concentration vs time data by using population pharmacokinetic methods. Results of the pharmacodynamic-pharmacokinetic relationships showed that both the ACT and APTT methods yielded a linear increase according to the S 18326 concentration measured using a highly sensitive analytical method. At the end of infusion, ACT was prolonged 1.20 and 1.95-fold in the 0.5 mg h-1 and the 3 mg h-1 groups, respectively, and APTT was prolonged 1.27 and 2.75-fold. Thrombin inhibition plateaued above 0.5 microm of S 18326 according to an Emax model, confirming that the test was highly sensitive. F1 + 2 levels fell significantly after the 24 h S 18326 infusion (0.83 nm to 0.6 nm and 0.80 nm to 0.44 nm in the 0.5 mg h-1 and the 3 mg h-1 groups, respectively), but remained stable after the placebo infusion. CONCLUSIONS Our results support specific monitoring of the thrombin inhibitor S 18326 with ACT and APTT to establish the safety range of the drug in further studies. Moreover, the fall in F1 + 2 prothrombin fragments suggests that S 18326 effectively reduces the retroactivation of factors V and VIII by thrombin.
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Affiliation(s)
- Pascale Gaussem
- Unité INSERM 428, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris V, 4 avenue de l'Observatoire, F-75270 Paris Cedex 06, France.
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Sherman DS, Clarke SH, Lefkowitz JB, Valuck RJ, Lindenfeld J, Stringer KA. An institution-specific heparin titration nomogram: development, validation, and assessment of compliance. Pharmacotherapy 2001; 21:1167-74. [PMID: 11601661 DOI: 10.1592/phco.21.15.1167.33895] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
STUDY OBJECTIVE To develop, validate, and assess compliance with a heparin titration nomogram. DESIGN Prospective, open-label trial. SETTING University teaching hospital. SUBJECTS Patients admitted with heart failure who required therapy with intravenous unfractionated heparin. Intervention. An in vitro concentration-response was determined by measuring activated partial thromboplastin times (aPTTs) on normal pooled plasma containing known concentrations of heparin. The therapeutic aPTT range was determined from the concentration-response by using the therapeutic heparin concentration range of 0.2-0.4 U/ml (protamine neutralization). Patients were consecutively enrolled, and therapy was managed by using the heparin titration nomogram. Paired aPTT-heparin concentrations were obtained, and nomogram validation was performed by comparing the in vitro and the ex vivo concentration-responses with use of linear regression. Nomogram compliance also was assessed. MEASUREMENTS AND MAIN RESULTS The therapeutic aPTT ranges based on in vitro and ex vivo data were determined to be 45-72 seconds and 47-61 seconds, respectively. The ranges were significantly different (p<0.001). Overall compliance with the nomogram was 88%. CONCLUSION These results confirm that, even in a relatively homogeneous disease-state patient population, in vitro data do not accurately predict ex vivo data. If in vitro data are used to develop an institution-specific nomogram, a validation procedure should be used to ensure accuracy. Although 100% compliance to a nomogram may not be attainable, it should be expected. Therefore, a compliance rate of 88% is concerning and suggests a need for increased nursing and physician education.
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Affiliation(s)
- D S Sherman
- Department of Pharmacy Practice, School of Pharmacy, University of Colorado Health Sciences Center, Denver 80262, USA
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Mischke R, Jacobs C. The monitoring of heparin administration by screening tests in experimental dogs. Res Vet Sci 2001; 70:101-8. [PMID: 11356088 DOI: 10.1053/rvsc.2000.0447] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective of this study was to investigate the relationship between different screening tests of haemostasis and amidolytic plasma activities of unfractionated (standard) heparin in dogs. Different doses of intravenous (i.v.) [25, 50 or 100 IU Kg(-1)bodyweight (BW)] and subcutaneous (s.c.) heparin (250, 500 and 750 IU kg(-1)) were given to groups each of five clinically healthy adult beagles. Measurements of heparin activity with a factor Xa-dependent chromogenic substrate, activated partial thromboplastin time (APTT) (two different reagents), thrombin time (TT, two different thrombin activities in the reagent: 3 and 6 IU ml(-1)) and the reaction time of the resonance thrombogram (RTG -r) with two different measuring devices were performed at different times. The relationship between ratio values (actual/baseline values) of the coagulation tests and heparin activity was analysed based on regression analysis and correlation coefficient. The greatest alterations were seen for the TT([3 IU ml(-1)])and the RTG -r which were near or exceeded the upper limit of measuring range, if 25 IU kg(-1)BW heparin were given i.v. at heparin plasma levels of 0.54 +/- 0.13 IU ml(-1). These results show, that only APTT and TT measured with high thrombin activity assay appear suitable for guiding high dose heparin therapy in dogs. Averaged alterations of APTT ratio in canine plasma were less than those observed in people for similar plasma heparin levels, indicating that the guideline extrapolated from people for monitoring high dose heparin therapy using APTT may not be valid for use in dogs. After coagulation times had been converted into ratio values, based on regression analysis and Wilcoxon's test, differences of heparin sensitivity were found not only for TT measured with different thrombin activities but also for different APTT reagents (P < 0.001). The correlation between amidylotic antifactor Xa activity and ratio of coagulation times was only moderate and found to be lower for RTG -r (instrument 1: r(s)= 0.711; instrument 2: r(s)= 0.573) than for the other coagulation tests (r(s)= 0.822 to r(s)= 0.890). This indicates a considerable variability of the ratio values of the screening tests at defined heparin plasma activities. These results show, that blood coagulation tests in general are little or unsuitable for heparin antifactor-Xa activity control.
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Affiliation(s)
- R Mischke
- Clinic for Small Animals, School of Veterinary Medicine Hannover, Germany.
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Ip BK, Thomson AR, Moriarty HT. A comparison of the sensitivity of APTT reagents to the effects of enoxaparin, a low-molecular weight heparin. Pathology 2001. [DOI: 10.1080/00313020126304] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Ohman EM, Harrington RA, Cannon CP, Agnelli G, Cairns JA, Kennedy JW. Intravenous thrombolysis in acute myocardial infarction. Chest 2001; 119:253S-277S. [PMID: 11157653 DOI: 10.1378/chest.119.1_suppl.253s] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- E M Ohman
- Duke Clinical Research Institute, Durham, NC 27715, USA.
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