Hemostasis Tests Research Articles

The Clinical Utility of Tranexamic Acid in the Management of Refractory Bleeding in a Patient With Advanced Liver Disease

Advanced liver disease is associated with coagulopathy and bleeding that develops from several mechanisms. In common clinical practice, the bleeding is treated with blood products and/or pharmacologic agents based on their corrective effect on laboratory tests of hemostasis. We report the case of a 72-year-old man with end-stage liver disease with refractory bleeding in whom multiple therapeutic strategies failed, including massive blood product replacement, but who responded to the infusion of tranexamic acid, an anti-fibrinolytic agent. The hyper-fibrinolytic state is difficult to diagnose with conventional clinical laboratory tests, but it was suspected in this patient with refractory bleeding and hypo-fibrinogenemia. Although largely used in the surgical setting, tranexamic acid may prove useful in medical settings characterized by bleeding and systemic fibrinolysis. J Hematol. 2014;3(2):46-49 doi: http://dx.doi.org/10.14740/jh151w

Simple and rapid assay for effect of the new oral anticoagulant (NOAC) rivaroxaban: preliminary results support further tests with all NOACs

BackgroundNew oral anticoagulant (NOAC) drugs are known to influence the results of some routine hemostasis tests. Further data are needed to enable routine assessment of the effects of NOAC on clotting parameters in some special circumstances.MethodsFollowing administration of rivaroxaban to patients, at the likely peak and trough activity times, we assessed the effects on prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and clotting time using Russell’s viper venom, and in the presence of phospholipids and calcium reagent available as DVVreagent® and DVVconfirm®. The data were used to determine an adequate NOAC plasma level based on anticoagulant activities expressed as a ratio (patients/normal, R-C).ResultsDVVconfirm as R-C could be rapidly performed, and the results were reasonably sensitive for rivaroxaban and probably for other FX inhibitors. This assay is not influenced by lupus anticoagulant and heparin, does not require purified NOAC as control, and will measure whole-plasma clotting activity.ConclusionsWe propose a cut-off R-C value of 4.52 ± 0.33 for safety, but clinical studies are needed to establish whether this cut-off is useful for identifying patients at increased risk of hemorrhage or exhibiting low anticoagulation effect. It also seems possible that normal R-C could indicate an absence of anticoagulant activity when rivaroxaban is discontinued due to episodes of uncontrolled bleeding during anticoagulation or for emergency surgery.

EVALUASI ADVERSE DRUG REACTIONS DAN EFEKTIVITAS PENGGUNAAN KETOROLAK PADA PASIEN PASCA BEDAH SARAF DI RUMAH SAKIT UMUM PENDIDIKAN DR. WAHIDIN SUDIROHUSODO MAKASSAR

Pain is often experienced by patients treated in the hospital and is the most frequently reported events in post-surgical patients. Ketorolac associated with the incidence of adverse reactions include, the incidence of acute renal failure and bleeding disorders. The purpose of the study was to observe and report on the profile of adverse reactions include the use of ketorolac on renal function and hemostasis as well as the effectiveness of the analgesic ketorolac. A total of 20 patients who received ketorolac compared to the value of the glomerular filtration rate (GFR), bleeding time (BT), Blood Clotting Time (CT), prothrombin time (PT) and International Normalized Ratio (INR) between before and after patients received ketorolac. Compared to the value of the Visual Analog Scale (VAS) ranging V day I to day administration of ketorolac. One of 20 patients (5%) who use ketorolac for 5 days had decreased GFR by 66.70%.. Whereas for hemostasis testing showed that ketorolac can influence hemostatic seen from increasing on BT (0,04; p 0,05). Conclusion. incidence of renal damage incident occurred at 5%, and may affect hemostatic function in patients. Resolution of pain may occur at day 4 ketorolac administration. Key word : Evaluation, Adverse Effects, Effectiveness, Ketorolac, Post-Nerve Surgical Patient

Total Laboratory Automation of Routine Hemostasis Testing

The aim of this study was to assess whether preanalytical management of coagulation samples through an open total laboratory automation system may impair the reliability of routine hemostasis tests as compared with loading of centrifuged plasma specimens directly into the coagulation analyzer for routine testing. Forty inpatient samples were divided into two aliquots. The former was centrifuged and directly loaded in a hemostasis analyzer, whereas the latter was entered into a 16.5 m long track-line system (FlexLab), where it was automatically centrifuged and conveyed to the same coagulation analyzer. An analytically significant difference was found between values of samples directly loaded in the coagulation analyzer and those entered in the track-line system for prothombin time (19.6 ± 1.7 versus 19.2 ± 1.6 s; p < 0.001) and activated partial thromboplastin time (38.0 ± 1.4 versus 37.5 ± 1.3 s; p = 0.021) but not for fibrinogen (305 ± 12 versus 304 ± 12 mg/dL; p = 0.97). Nevertheless, the mean percentage bias of prothombin time (-1.8%), activated partial thromboplastin time (-1.0%), and fibrinogen (0.4%) was modest and always lower than the total allowable error and was thereby considered not clinically significant. The results of this study confirm that connection of coagulation analyzers to track-line systems is a viable solution for modern clinical laboratories.

Hemostasis dynamics during coagulopathy resulting from Echis envenomation

This work provides a graphic description of the time course of hemostasis tests results during spontaneous evolution of Echis envenoming and correction of hemostasis disorders with antivenom therapy.The dynamics of fibrinogenemia (g L−1), prothrombin time (PT, %), activated partial thromboplastin time (aPTT, patient/normal ratio) and platelet count (Giga L−1) were collected from coagulopathic envenomed patients of a 12 years prospective study in Africa. Sixty patients were included. 47 of them (78%) received an antivenom (33 ± 12 ml) and 13 did not. Thirty patients (50%) presented bleeding. Only one patient died. The time for fibrinogen to be more than 1 g L−1 was 181 ± 116 h (7.5 days) in the spontaneous evolution group versus 40 ± 21 h in the antivenom group (p < 0.0001). The times for reaching a PT above 50% were 140 ± 64 min (5.8 days) versus 25 ± 15 h (p < 0.00001) and for reaching an aPTT less than 1.5 times the normal values, 116 ± 76 h (4.7 days) versus 10 ± 9 h respectively (p < 0.0002). Thrombopenia was not a common feature of Echis envenomation.This study is the first one to provide a chart of the evolution of the hemostatic tests during envenomation caused by Echis bites. The plots enable to estimate that, in Echis envenomation, in the absence of antivenom administration, hemostasis remains severely affected until the 8–10th day of evolution. On the contrary, efficient antivenom against African vipers corrects clotting functions within a few hours.

Clinical markers of the hypercoagulable state by rotational thrombelastometry in obese patients submitted to bariatric surgery

Metabolic and inflammatory disturbances associated with obesity are considered important trigger factors for venous thromboembolism (VTE). Identification of clinical markers indicating a hypercoagulability state could define a group of high-risk patients in the surgical setting. This study aimed to identify these markers using rotational thrombelastometry (ROTEM) analysis, an established method for hemostasis testing that can detect hyperfunctional stages of the clotting process. From June to December 2010, this study investigated 109 consecutive obese patients (28 women and 22 men, mean age 46 years, body mass index 46.6 ± 7 kg/m(2)) with no history of VTE who were candidates for bariatric surgery. Preoperative clinical and metabolic characteristics and ROTEM analysis were recorded. Hypercoagulable risk was defined when patients showed a clot strength (G) of ≥11 dynes/cm(2). Of the 109 patients, 20 (18%) were hypercoagulable according to ROTEM analysis. Metabolic/inflammatory biomarkers such as leptin, C-reactive protein, fibrinogen levels, and platelet count were significantly higher in the high-risk patients. In the multivariate analysis, fibrinogen was an independent predictor of G ≥ 11 dynes/cm(2) [odds ratio (OR) 2.92, 95 % confidence interval (CI) 1.80-5.21, p = 0.023]. After adjustment to other data, only waist circumference affected the prediction [OR 4.42, 95 % CI 2.27-6.71, p = 0.009]. Receiver operating characteristic curve analysis showed that 3.95 g/l was the best cutoff point for fibrinogen predictability (sensitivity 100 %, specificity 41%). A hypercoagulability state in obese patients is associated with central obesity and high fibrinogen levels, which should be considered clinical hallmarks of this state. More aggressive perioperative prophylaxis for VTE should be recommended when these hallmarks are present in obese patients.

Influence of Residual Platelet Count on Routine Coagulation, Factor VIII, and Factor IX Testing in Postfreeze-Thaw Samples

The use of frozen-thawed samples rather than fresh samples for specialized coagulation testing is becoming commonplace, thereby creating novel risks that may jeopardize the quality of hemostasis testing. Residual platelets (PLTs) in frozen plasma are most critical as freezing-induced activation and injury may impair routine and specialized testing after thawing. The aim of this study was to verify the impact of postcentrifugation PLT count in postfreeze-thawed samples on activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen, factor VIII (FVIII) activity testing, and factor IX (FIX) activity testing. These parameters were herein assessed in postfreeze-thaw paired plasma samples collected from 15 healthy volunteers and subjected to 4 different centrifugation forces (i.e., 3,000, 1,500, 1,000, and 500g), using data obtained with centrifugation force of 1,500g as the gold standard, in agreement with current recommendations. Compared with reference samples, PLT counts in fresh aliquots were indistinguishable in specimens centrifuged at 1,000g, significantly lower in those centrifuged at 3,000g and significantly higher in those centrifuged at 500g. In all cases except samples centrifuged at 3,000g, the PLT count was significantly decreased in postfreeze-thaw compared with paired fresh specimens. In postfreeze-thaw plasma, APTT was not influenced by residual PLT count. The results of PT and fibrinogen were consistently altered in samples centrifuged at 1,000 and 500g, though the correlation with the reference measures remained clinically acceptable. Data obtained for FVIII and FIX activities revealed a positive bias in all postfreeze-thaw plasmas, achieving statistical significance in samples centrifuged at 3,000g. We conclude that alteration of centrifuge speeds away from the recommended 1,500g may influence the level of residual PLTs in sample centrifuged at lower speeds such as 500g, and therefore may make these specimens unsuitable for hemostasis testing in postfreeze-thawed plasma samples. In addition, although the changes seen in FVIII and FIX in samples centrifuged at 3,000g may reflect non-PLT-related effects, such changes should also be considered in this setting.

Sample collection and platelet function testing

As for other tests of hemostasis, the investigation of platelet function is highly vulnerable to a broad series of preanalytical variables, which span from patient preparation to the final analysis of the specimen and issuance of test results. In particular, there remains much controversy about the influence of manual or vacuum aspiration of blood into primary collection tubes on platelet function testing. Accordingly, we investigated this for the PFA-100. In 12 healthy volunteers, a sample labeled as 'BD-V' was drawn into a 2.7 ml BD Vacutainer tube, whereas two additional samples were collected from the opposite arm into 5.0 ml Sarstedt S-Monovette tubes by vacuum (SD-V) or manual aspiration (SD-A). All sample were tested on PFA-100 with collagen and ADP (CADP) or collagen and epinephrine (CEPI). The values of both CEPI and CADP obtained in SD-A samples were significantly lower than those obtained in SD-V and BD-V tubes, whereas those of the two evacuated tubes did not significantly differ. On average, CEPI values were prolonged by 11% in SD-V and 13% in BD-V, whereas those of CADP were prolonged by 14% in SD-V and 10% in BD-V, respectively. These findings suggests that the lower shear stress generated by the manual aspiration of blood into the primary collection tube would prevent spurious hyper-activation of platelets, thus, preserving the integrity of their function for subsequent testing on PFA-100. This study underscores the need to define or validate local reference ranges for the PFA-100 based on the collection tube used. Different reference ranges of both CEPI and CADP may also be advisable when venous blood samples are collected with manual aspiration or vacuum principle.

Cerebral venous thrombosis and Buerger’s disease

In November 2011, a 44-year-old male patient developed progressive and intense headaches accompanied with vomiting and blurred vision. Five years ago, he was diagnosed with severe arteritis attributed to thromboangiitis obliterans (Buerger’s disease), requiring sympatholysis and implantation of a neurostimulator due to severe chronic pain. Despite smoking cessation in March 2010, he had his right leg amputated in August 2010 (panel A) and 1 month later he presented with signs suggestive of acute anterior myocardial infarction. Coronarography disclosed subocclusion of the anterior interventricular artery due to a movable clot, without underlying artery stenosis; the clot was removed by catheter aspiration. Patient was placed under clopidogrel 75 mg and aspirin 80 mg daily from that moment and no either significant event was reported since its admission at the emergency room. Head CT scans (panels B and C) revealed extensive thrombus of the superior longitudinal sinus (arrowheads), the straight sinus and the vein of Galen (arrows), as well as the inferior longitudinal and the right transverse sinuses (not shown). D-dimers and fibrinogen were transiently moderately elevated (0.9 lg ml [normal \0.5] and 591 mg % [normal: 170–400]). Prothrombin time and platelet count were normal. Long-term anticoagulation therapy was started. Further hemostasis testing revealed no coagulation disorder (homocystein was slightly elevated: 16.9 lmol l [normal: 5–15]; antithrombin and activated partial thromboplastin time values were within the normal range; G20210A prothrombin mutation, activated protein C resistance, anticardiolipin antibodies, circulating anticoagulants and anti B2GP1 antibodies were negative). Clinical resolution and radiological improvement were observed after 3 months of treatment and no further complications reported. Cerebral venous thrombosis (CVT) is a rare stroke type, but it is also the only one that can be cured before the pathology of the vessel has led to damage of the brain parenchyma. While headaches are the most common signs of CVT, 60–90 % of patients will develop cerebral— potentially fatal—complications without prompt initiation of anticoagulant therapy [1]. A brain MRI was not available in our patient, due to implanted neurostimulator, so that thrombus was evidenced using CT scan. Interestingly, diagnosis was already suspected based on an unenhanced CT scan of the brain, a routine test available at the emergency department (Fig. 1). Although there are numerous factors predisposing a patient to develop CVT, BD is not listed among them [1]. We found three previous reports presenting associations of CVT and BD [2–4]. Questioning more specifically the link between CVT and BD could therefore bring a new perspective to clinicians studying these conditions. This is particularly true for BD, since the pathogenesis of this disease is still largely unknown [5]. Yet, smoking is known to influence BD activity. In our patient, CVT occurred 20 months after smoking cessation, while the last arterial event was reported 6 months after the cessation. A causal association may thus appear less likely. Conversely, no common risk factor for CVT was found in our patient, J.-M. Raymackers (&) Department of Neurology, Clinique Saint-Pierre, 9 avenue Reine Fabiola, 1340 Ottignies, Belgium e-mail: je.raymackers@clinique-saint-pierre.be

Laboratory diagnostic markers in assessing the state of patients with osteoarthrosis, who need prosthetic arthroplasty of large joints (a review of literature)

The paper considers the use of hemostasis, biochemical and immunological tests in patients with osteoarthritis of the large joints (knee, hip) during replacement. Given existing in the modern laboratory diagnosis markers, which is used on patients to evaluate the health status before and after joint replacement.

Nouveaux anticoagulants oraux en soins primaires : point de vue du médecin généraliste

The assessment of new anticoagulants benefits is based on the assessment of thromboembolism and bleeding risks, referring when possible to CHA2DS2-VASc and HAS-BLED scores. The management of patients treated with new anticoagulants includes a clinical assessment and the annual measure of the creatinine clearance (three times per year in some particular cases). New anticoagulants make hemostasis tests not reliable. The general practitioner has a role in preventing interactions and reporting potential adverse drug reactions. The context of uncertainty about the risk/benefit ratio of new anticoagulants emphasizes the need to integrate the values of the patient in treatment decisions.

Technical Evaluation of the Novel Preanalytical Module on Instrumentation Laboratory ACL TOP: Advancing Automation in Hemostasis Testing

Automation in hemostasis testing is entering an exciting and unprecedented phase. This study was planned to assess the performance of the new preanalytical module on the hemostasis testing system Instrumentation Laboratory ACL TOP. The evaluation included interference studies to define reliable thresholds for rejecting samples with significant concentrations of interfering substances; within-run imprecision studies of plasma indices on four different interference degrees for each index; comparison studies with reference measures of hemolysis index, bilirubin, and triglycerides on clinical chemistry analyzers; and calculation of turnaround time with and without automatic performance of preanalytical check. The upper limits for sample rejection according to our interference studies were 3.6 g/L for hemoglobin, 13.6 mg/dL for bilirubin, and 1454 mg/dL for triglycerides. We found optimal precision for all indices (0.6% to 3.1% at clinically relevant thresholds) and highly significant correlations with reference measures on clinical chemistry analyzers (from 0.985 to 0.998). The limited increase of turnaround time (i.e., +3% and +5% with or without cap-piercing), coupled with no adjunctive costs over performance of normal coagulation assays, contribute to make the automatic check of plasma indices on ACL TOP a reliable and practical approach for improving testing quality and safeguarding patient safety.

Transfusion support for Trauma

Severely injured patients are at a risk of acute traumatic coagulopathy contributing to high mortally rates. The early use of tranexamic acid in this setting has been shown to be safe and improves survival. Optimal FFP: Red cell ratios needed with respect to outcomes are yet to be defined. Slow turnaround times associated with the use of laboratory based coagulation testing can lead to delays in appropriate component support with a need for validated algorithms for near patient global tests of haemostasis. Multidisciplinary protocols are required for managing traumatic haemorrhage with emphasis on good communication supported by training, audit and on‐going review of cases to optimise patient care.

Low endogenous thrombin potential in trained subjects

IntroductionA paradox seems to exist: exercising leads to clotting activation in conventional clotting tests, but exercising persons have a low risk of thrombosis. In this study we tried to evaluate the effect of exercise performance status on in vitro plasma thrombin generation, which represents an overall function test of hemostasis. Materials and MethodsWe compared 56 trained subjects to 98 healthy age matched sedentary volunteers. Blood samples were analyzed for thrombin generation using calibrated automated thrombography. Microparticles were quantified using ELISA. Additionally prothrombin fragments 1+2, thrombin-antithrombin complex, tissue factor pathway inhibitor, antithrombin and prothrombin were measured. The group of the trained subjects performed an incremental cycle-ergometer exercise test after taking the blood sample. ResultsA significantly lower endogenous thrombin potential was observed in the group of the trained subjects compared to the sedentary individuals (p=0.007). Microparticles (ELISA) were significantly lower in the trained subjects compared to the sedentary subjects (p=0.001). Prothrombin fragments 1+2 (p<0.001) and thrombin-antithrombin complex (p=0.01) were significant higher in the trained subjects and antithrombin (p=0.02) as well as prothrombin (p<0.0001) were significantly lower in this group, whereas tissue factor pathway inhibitor values did not show significant differences. Both maximal and submaximal power output was significantly negatively related to endogenous thrombin potential (r=-0.43, r=-0.45) and thrombin peak (r=-0.44, r=-0.42). ConclusionsTrained subjects have a lower endogenous thrombin potential than sedentary subjects possibly explaining the lower incidence of thrombosis in this group despite a higher acute clotting activation during strenuous exercise.

Molecular testing for disorders of hemostasis

The investigation of inherited bleeding disorders with routine tests of hemostasis will yield clear diagnostic information in the majority of subjects with an unequivocal history of bleeding and especially in those where the phenotypic severity is severe and where an obvious family history of bleeding is present. Nevertheless, a significant minority of subjects with obvious bleeding symptoms will remain without a definite diagnosis after extensive hemostatic testing. With these facts in mind, the role of molecular testing for inherited disorders of hemostasis now includes the following: confirmation of a phenotypic diagnosis through targeted genetic analysis, the distinction of bleeding phenocopies by molecular analysis, and provision of genetic testing as the investigation of choice in situations such as prenatal diagnosis and detection of the carrier state for inherited bleeding traits. In addition, molecular testing can sometimes be used to provide supplementary knowledge that can be used to enhance clinical care. Finally, the utility of genome-wide approaches to identify novel genetic associations may provide new information to explain the cause of bleeding in the population of bleeders without established diagnoses.

Pre-interventional haemostatic assessment

Recently the French Society of Anaesthesia and Intensive Care (Société Française d'Anesthésie et de Réanimation [SFAR]) issued recommendations for the prescription of routine preoperative testing before a surgical or non-surgical procedure, requiring any type of anaesthesia. Thirty clinical specialists performed a systematic analysis of the literature, and recommendations were then developed using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system. One part of these guidelines is dedicated to haemostatic assessment. The goal of pre-anaesthetic screening for congenital or acquired haemostatic disorders is to prevent perioperative haemorrhagic complications through appropriate medical and surgical management. Preoperative assessment of bleeding risk requires a detailed patient interview to determine any personal or family history of haemorrhagic diathesis, and a physical examination is necessary in order to detect signs of coagulopathy. Laboratory investigation of haemostasis should be prescribed, not systematically, but depending on clinical evaluation and patient history. Standard tests (prothrombin time, activated partial thromboplastin time, platelet count) have a low positive predictive value for bleeding risk in the general population. Patients with no history of haemorrhagic diathesis and no conditions liable to interfere with haemostasis should not undergo pre-interventional haemostasis testing. Conversely, the existence of a positive history or a disease that could interfere with haemostasis should be an indication for clinically appropriate testing.

Pre-analytical issues in the measurement of circulating microparticles: current recommendations and pending questions

Pre-analytical issues in the measurement of circulating microparticles: current recommendations and pending questions

Prise en charge des troubles de l’hémostase chez l’insuffisant hépatique

Patients with end-stage liver disease have complex alterations that involve all components of hemostasis, with changes both in prohemostatic and in antihemostatic pathways. Routine haemostasis tests such as prothrombin time and platelet count are unable to reflect a bleeding tendency. Bleeding complications are much less related to abnormal hemostasis than previously thought, with portal hypertension playing a more critical role. Systematic prophylactic measures based upon the use of fresh frozen plasma and/or platelet concentrates to improve or correct the abnormalities of the routine coagulation tests are most often inappropriate and may occasionally be deleterious.

Regulation in Hemostasis and Thrombosis: Part I—In Vitro Diagnostics

The diagnostic or test-performance process, as associated to the evaluation or diagnosis of hemostasis and thrombosis and related disorders, is influenced or controlled by the activity of a large number of professional, expert, and government organizations. These may be involved in driving standardization or harmonization, providing professional or expert guidelines, or in regulation of therapeutic products and diagnostic products such as in vitro diagnostic devices or reagents (IVDs). Although all organizations involved in this activity would propose an intention to drive improvements in diagnostics and human health and although there are benefits to the overall process of standardization and regulation for tests of hemostasis and thrombosis, it should also be recognized there are several specific problems and limitations to this process. As highlighted in this report, which specifically relates to the regulation of IVDs, several case studies are used as examples to show that regulation, aimed to reduce risks associated with the implementation of diagnostic testing, may instead encourage the adverse outcome of locking out clinically useful, new, and improved technologies and locking in old and outdated technologies. This has a potential for significant adverse outcomes related to the clinical diagnosis and management of hemostasis and thrombosis-related disorders.

Emergency assessment of hemostasis in the bleeding patient

Emergency hemostasis testing is typically used to determine which blood products are needed to correct hemostatic defects associated with bleeding. Rapid assessment of hemostasis can be performed using standard or viscoelastic hemostasis tests in the clinical laboratory, satellite laboratory, or using point-of-care methods. The major drawback of standard coagulation testing is that most clinical laboratories are focused more on accuracy than on turnaround time. Improving turnaround times may require revision of the entire approach to performing the testing in the clinical laboratory including specimen processing, testing, and reporting. An advantage to rapid central laboratory testing is the availability to all areas of the hospital, not just the emergency department or operating rooms. Use of point-of-care assays can improve turnaround times, but point-of-care tests typically show more variation and lower precision. Viscoelastic global hemostasis tests can be used for rapid assessment as well, but care needs to be taken in the interpretation of the results. Viscoelastic testing is currently the only method that can detect severe fibrinolysis. Platelet function testing is useful for detection of hereditary platelet function problems and some antiplatelet medication monitoring, but is less useful for preoperative bleeding risk assessment or diagnosing the cause of acquire bleeding syndromes. This review will highlight different approaches to the rapid assessment of hemostasis.