Evaluation of a modified thromboelastography assay for the screening of von Willebrand disease

2011 ◽  
Vol 105 (06) ◽  
pp. 1091-1099 ◽  
Author(s):  
Hans-Georg Topf ◽  
Dominik Weiss ◽  
Grischa Lischetzki ◽  
Erwin Strasser ◽  
Wolfgang Rascher ◽  
...  
Keyword(s):  
Point Of Care ◽  
Area Under The Curve ◽  
Maximum Amplitude ◽  
Von Willebrand Disease ◽  
Infusion Therapy ◽  
Clot Strength ◽  
Point Of Care Test ◽  
Diagnosis And Classification ◽  
Patient Groups ◽  
Von Willebrand

SummaryThromboelastography (TEG) has been shown to be a valuable point-of-care device for the rapid diagnosis of various bleeding disorders. However, TEG has thus far not been used for the screening for von Willebrand disease (VWD). We evaluated the performance of a modified TEG assay for the laboratory screening of VWD. Three hundred twenty-eight patients (148 male, 180 female, median age 8.4 years, range 0.1 – 72.7 years) were included in the study. The diagnosis and classification of patients was based on personal and familial case history, von Willebrand factor antigen, ristocetin cofactor levels, collagen binding assay, factor VIII coagulant activity and multimer analysis. The ratio of clot strength after preincubation with ristocetin, and without ristocetin, represents the component of clot strength that is formed by cross-linked fibrin fibres and is dependent on the agglutinated platelet fraction. The decrease of the maximum amplitude is a function of the ristocetin concentration and provides a diagnostic parameter able to differentiate between healthy individuals and patients having VWD. Based on a preliminary cut-off value of 25% for the area under the curve (AUC) ratio, the sensitivity varied from 53% to 100% for the different VWD patient groups. The test is suitable for use as a screening test using whole blood and has the additional benefit of being suitable as a point of care test. It appears also useful for monitoring responses to desmopressin (DDAVP) and infusion therapy.

scholarly journals Identification of hypercoagulability with thrombelastography in patients with hip fracture receiving thromboprophylaxis

2021 ◽  
Vol 64 (3) ◽  
pp. E324-E329
Author(s):  
Daniel You ◽  
Leslie Skeith ◽  
Robert Korley ◽  
Paul Cantle ◽  
Adrienne Lee ◽  
...  
Keyword(s):  
Hip Fracture ◽  
Point Of Care ◽  
Common Complication ◽  
Maximal Amplitude ◽  
Clot Strength ◽  
Hip Fracture Surgery ◽  
Point Of Care Test ◽  
Trochanteric Region ◽  
Fracture Surgery ◽  
Over Time

Background: Venous thromboembolism (VTE) is the second most common complication after hip fracture surgery. We used thrombelastography (TEG), a whole-blood, point-of-care test that can provide an overview of the clotting process, to determine the duration of hypercoagulability after hip fracture surgery. Methods: In this prospective study, consecutive patients aged 51 years or more with hip fractures (trochanteric region or neck) amenable to surgical treatment who presented to the emergency department were eligible for enrolment. Thrombelastography, including calculation of the coagulation index (CI) (combination of 4 TEG parameters for an overall assessment of coagulation) was performed daily from admission until 5 days postoperatively, and at 2 and 6 weeks postoperatively. All patients received 28 days of thromboprophylaxis. We used single-sample t tests to compare mean maximal amplitude (MA) values (a measure of clot strength) to the hypercoagulable threshold of greater than 65 mm, a predictor of in-hospital VTE. Results: Of the 35 patients enrolled, 11 (31%) were hypercoagulable on admission based on an MA value greater than 65 mm, and 29 (83%) were hypercoagulable based on a CI value greater than 3.0; the corresponding values at 6 weeks were 23 (66%) and 34 (97%). All patients had an MA value greater than 65 mm at 2 weeks. Patients demonstrated normal coagulation on admission (mean MA value 62.2 mm [standard deviation (SD) 6.3 mm], p = 0.01) but became significantly hypercoagulable at 2 weeks (mean 71.6 mm [SD 2.6 mm], p < 0.001). There was a trend toward persistent hypercoagulability at 6 weeks (mean MA value 66.2 mm [SD 3.8 mm], p = 0.06). Conclusion: More than 50% of patients remained hypercoagulable 6 weeks after fracture despite thromboprophylaxis. Thrombelastography MA thresholds or a change in MA over time may help predict VTE risk; however, further study is needed.

scholarly journals Diagnostic relevance of neutrophil gelatinase-associated lipocalin in early detection of acute kidney injury

2020 ◽  
Vol 7 (2) ◽  
pp. 88-92
Author(s):  
Madhusudhan Mahadevaiah ◽  
Murali Mohan Nidasale Thimmaiah ◽  
Venu Sashank Yerramsetty ◽  
Jeevan Kumar ◽  
Ranjith Kumar
Keyword(s):  
Acute Kidney Injury ◽  
Diagnostic Accuracy ◽  
Point Of Care ◽  
Area Under The Curve ◽  
Kidney Injury ◽  
Neutrophil Gelatinase Associated Lipocalin ◽  
Plasma Ngal ◽  
Point Of Care Test ◽  
Reliable Marker ◽  
Neutrophil Gelatinase

Objective: To evaluate the predictive and diagnostic accuracy of neutrophil gelatinase-associated lipocalin (NGAL) in acute kidney injury (AKI) and also to predict the renal replacement therapy (RRT) using NGAL as a marker. Methods: This prospective study was conducted among the patients admitted to intensive care units. Plasma samples were collected 24 hours after admission and NGAL was measured using Triage® NGAL test, a specific point of care test which is based on the mechanism of fluorescence immunoassay. The diagnostic accuracy of plasma NGAL (pNGAL) to predict AKI in critically ill patients of ICU was assessed by applying receiver operator curve (ROC) analysis and calculating the area under the curve (AUC). Results: In this study, 100 patients with the mean age of 49.56±19.2 years were included for the period of 18 months. The blood samples were withdrawn from the patients 24 and 44 hours after admission. Totally, 55% (n=55) of ICU patients were diagnosed with AKI. Plasma NGAL level was significantly increased in AKI patients as compared to non-AKI patients (742.65±734.72 vs. 255.62±440.09 μg/L; P<0.01). The sensitivity and specificity of NGAL for diagnosing AKI was 83.6% and 88.9%, respectively. The overall diagnostic accuracy was 86%. Diagnostic accuracy of NGAL for requirement of RRT was 51%. Conclusion: Plasma NGAL is a reliable marker for patients with AKI in ICU, in case the cause of kidney injury is not known. In addition, NGAL also predicts the RRT need based on AKI severity.

scholarly journals Assessing the clinical impact and resource use of a 30-minute chlamydia and gonorrhoea point-of-care test at three sexual health services

2021 ◽  
Vol 8 ◽  
pp. 204993612110616
Author(s):  
Susie Huntington ◽  
Georgie Weston ◽  
Elisabeth Adams
Keyword(s):  
Health Services ◽  
Sexual Health ◽  
Resource Use ◽  
Standard Care ◽  
Point Of Care ◽  
Structured Interviews ◽  
Process Data ◽  
Point Of Care Test ◽  
Clinical Benefits ◽  
Patient Groups

Objectives: To assess clinical metrics and resource use of a 30-minute point-of-care test (POCT) for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) compared to laboratory-based testing. Methods: Three English sexual health services (SHSs) were recruited as part of a study. Existing processes for CT/NG testing and treatment were assessed, and adaptions to incorporate the CT/NG POCT were developed during semi-structured interviews. Staff time and consumables data were collected by clinic staff prior to and following introduction of the POCT. Results: SHSs selected patient groups for whom the CT/NG POCT would be used. Testing and treatment process data were collected for 225 patients (n = 118 POC; n = 107 standard). The percentage of patients receiving unnecessary CT treatment was 5% (5/95) and 13% (12/93) for POC and standard care respectively. The average CT/NG pathway cost varied and was on average £61.55 for POC and £50.88 for standard care. For the two SHSs where the POCT was used during a patient’s visit, for standard and POC respectively, the average time to CT treatment was 10.0 and 0.0 days and to NG treatment, 0.3 and 0.0 days. Conclusion: Use of a 30-minute POCT at three SHSs yielded clinical benefits by reducing time to treatment and unnecessary CT treatment.

scholarly journals Evaluation of a new semi-automated Hydragel 11 von Willebrand Factor multimers assay kit for routine use

2020 ◽  
Author(s):  
Marika Pikta
Keyword(s):  
Von Willebrand Factor ◽  
Quantitative Estimation ◽  
Von Willebrand Disease ◽  
Diagnostic Process ◽  
Routine Practice ◽  
Significant Difference ◽  
Diagnosis And Classification ◽  
Von Willebrand ◽  
Willebrand Factor

Accurate diagnosis and classification of von Willebrand disease are essential for optimal management.  The von Willebrand factor multimers analysis is in the phenotypic classification, especially in discrepant cases, an integral part of the diagnostic process. The aim of this study was to evaluate the performance of a new Hydragel 11VWF multimer assay (H11VW). Results: Comparison study did not reveal any significant difference between H5VW and H11VW.  The assessment of within-subject results, using H5VW and H11VW, demonstrates the reproducibility of the method in both healthy and VWD patients’ samples collected over time, with identical multimeric pattern on densitometric curves.Conclusion: This assay demonstrated acceptable performance, produced within-day results and can be used in routine practice for the visual investigation of gel and quantitative estimation of VWF multimer fractions.

The Effect of Platelet -, and Leukocyte Count on the Thrombelastograph® (TEG) Parameters.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3971-3971
Author(s):  
W.W.H. Roeloffzen ◽  
J.C. Kluin-Nelemans ◽  
Joost de Wolf
Keyword(s):  
Platelet Count ◽  
Point Of Care ◽  
Maximum Amplitude ◽  
Multiple Regression Model ◽  
Clot Strength ◽  
Normal Limits ◽  
Coagulation Tests ◽  
Plasmatic Coagulation ◽  
Sensitivity Specificity ◽  
Normal Controls

Abstract Background. The TEG is used in situations were point of care testing of hemostasis is desired, although its value is still controversially because of insufficient test validation. The main parameters of the TEG are (a) the reaction time (R), the time until the initial fibrin formation and comparable with the coagulation times PT and APTT; (b) clotting time (K), the time until a fixed level of clot firmness is reached; (c) the angle (α) is closely related to K and measures the rapidity of fibrin build up and gives information about the clot strength; R, K and α are prolonged by anticoagulants and factor deficiencies; (d) maximum amplitude (MA) is a measurement of maximum strength or stiffness of the developed clot; it is especially influenced by platelets and fibrin. Methods. We performed a multivariate analysis using the Cox multiple-regression model to study the effects of Leukocytes, Hb, and platelet count on the TEG parameters. Results. Ninety native whole blood samples from 19 patients undergoing consolidation chemotherapy were studied; in the post chemotherapy phase in which platelets decreased from normal to < 10 x 109/l samples were taken; in all these cases PT, APTT and Fibrinogen were within normal limits. Platelets significantly influenced all parameters: R (p<0.001, r=−0.5), K (p<0.001, r=−0.7), α (p<0.001, r=+0.7), MA (p<0.001, r=+0.6) whereas Leukocytes influenced MA as well (p<0.001, r=0.3). In normal controls K is 9 ± 3 min (n=110), in patients with platelet count 50–100, 25–50 and <25 x 109/l K was resp. 17 ± 9, 30 ± 13 and 46 ± 10 min. In normal controls MA was 46 ± 7 mm, in patients MA became significant smaller with platelets < 25 x 109/l: 30 ± 5 mm. In patients with leukocytes ranging from 0–0.1, 0.1–1.0, 1.0–3.5 and > 3.5 x 109/l the MA was resp. 44 ± 14, 49 ± 15, 54 ± 9, and 58 ± 8 mm. As the MA is considered the parameter most influenced by platelet count, we calculated the sensitivity, specificity, pos and neg predictive value of MA to detect a platelet count less then 50 x 109/l, they were resp. 35%, 100%, 100% and 73%. Conclusion. Firstly, platelet count not only influences MA but also the coagulation parameters R, K and α; besides leukocytes influences the clot strength; this is in agreement with the new conceptual cell based model of hemostasis; secondly, the TEG should be considered as additive to platelet count and plasmatic coagulation tests and not as a replacement.

In Normal Controls, a Lower Hb Concentration and Female Sexe Increases Coagulability on the Thrombelastograph (TEG).

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3970-3970
Author(s):  
W.W.F. Roeloffzen ◽  
J.C Kluin-Nelemans ◽  
Joost de Wolf
Keyword(s):  
Platelet Count ◽  
Point Of Care ◽  
Maximum Amplitude ◽  
Multiple Regression Model ◽  
Point Of Care Testing ◽  
Clotting Time ◽  
Clot Strength ◽  
Angle Alpha ◽  
Hb Concentration ◽  
Normal Controls

Abstract Background. The TEG is used in situations were point of care testing of hemostasis is desired, although its value is still controversially because of insufficient test validation. The main parameters of the TEG are (a) the reaction time (R), the time until the initial fibrin formation and comparable with the coagulation times PT and APTT; (b) clotting time (K), the time until a fixed level of clot firmness is reached; (c) the angle (alpha) is closely related to K and measures the rapidity of fibrin build up and gives information about the clot strength; R, K and alpha are prolonged by anticoagulants and factor deficiencies; (d) maximum amplitude (MA) is a measurement of maximum strength or stiffness of the developed clot; it is especially influenced by platelets and fibrin. Methods. We performed a multivariate analysis using the Cox multiple-regression model to study the effects of sexe, age, Hb, platelet count, PT, APTT and fibrinogen on the TEG parameters. Results. Ninety nine normal controls (54 men) age 51 ± 17 years (range 19–87) were studied; no anticoagulants, antithrombotics or oral contraceptives were used. Native whole blood samples were used. The R is significantly influenced by sexe (p<0.001; r=0.4) and APTT (p<0.001; r=0.4); R is in women 19 ± 4, versus 24 ± 5 minutes in men. K is significantly influenced by Hb (p<0.001; r=0.5), fibrinogen (p<0.001; r=−0.4), platelet count (p=0.01; r=−0.3), sexe (p=0.018; r=−0.5) and APTT (p=0.009; r=0.4). The alpha is significantly influenced by the Hb (p<0.001; r=−0.5), fibrinogen (p=0.001; r=0.4), sexe (p=0.008; r=0.5) and APTT (p=0.03; r=−0.4). In normal controls with a Hb of resp.< 8, 8–9 or >=9 mmol/l the K was resp. 6.8 ± 1.7, 8.5 ± 2.5 and 10.5 ± 2.8 minutes; the alpha was resp. 31.4 ± 8.1, 26.1 ± 7 and 21.4 ± 5.8 degrees. The MA was significantly influenced by fibrinogen (p<0.001; r=0.5), age (p<0.001; r=0.5), sexe (p<0.001; r=0.4), platelet count (p=0.02; r=0.2) and PT (p0.03; r=0.1). Conclusion.. Coagulability measured in the TEG is increased in women compared to men (shortened R and K, larger alpha, increased MA) and coagulability increases with a decrease of the Hb concentration (shortened K and larger alpha).

A Novel Rapid Screening Assay for the Diagnosis of the Phenotypic Variants of Von Willebrand Disease (VWD)

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3567-3567
Author(s):  
Jonathan C Roberts ◽  
Patti A Morateck ◽  
Pamela A Christopherson ◽  
Ke Yan ◽  
Raymond G Hoffmann ◽  
...  
Keyword(s):  
Hemophilia A ◽  
Area Under The Curve ◽  
Von Willebrand Disease ◽  
Functional Screening ◽  
Single Individual ◽  
Screening Assay ◽  
Collagen Iii ◽  
Roc Area ◽  
Von Willebrand

Abstract Background von Willebrand disease (VWD) is a very common inherited bleeding disorder. The current phenotypic classification of VWD variants includes disorders of both quantitative and qualitative defects in von Willebrand Factor (VWF) that determines optimal treatment of patients. Current phenotype determination is multimodal, cumbersome, performed by only a few specialized laboratories, and may delay the definitive diagnosis necessary in proper selection of therapy. We have developed an ELISA-based strip assay that is capable of rapid determination of relative qualitative and quantitative VWF functionality to correctly assign phenotypic variants of VWD. Methods 136 VWD plasma samples from the Zimmerman PPG were analyzed on a new ELISA based platform. In single, individual wells this assay measures relative values of VWF:Ag (antigen), VWF:IbCo (Ib cofactor, no ristocetin), VWF:RCo (ristocetin cofactor), VWF:F8B (binding to FVIII), VWF:CB3 (binding to collagen III), and VWF:pp (propeptide) in comparison to a 30% normal control standard in a single ELISA strip assay. The study included 22 type 1 VWD, 32 type 1C VWD, 18 type 2A VWD, 23 type 2B VWD, 20 type 2M VWD, 7 type 2N VWD, 4 type 3 VWD, and 10 hemophilia A subjects. Each sample was run in single wells for each assay and optical densities (OD) were compared to the OD of a 30% standard control plasma and a 100% VWF:Ag control. The standard ELISA plate read time was 30 minutes and full assay can be accomplished in 3 hours. Two of the coauthors were blinded as to the Zimmerman PPG VWD phenotypes of test samples. Using the ELISA strip results, phenotype assignment was determined and then compared to the unblinded Zimmerman PPG VWD diagnosis. Further statistical analysis of VWF functional profile relationships was performed using the Mann-Whitney test and ROC analysis, and can quantify the ability to identify these phenotypes. Results VWF functional profiles based on visually observed ratio relationships correctly assigned VWD phenotypic variant on first attempt in 122 of 136 subjects (89.7%). Repeat testing of the 14 incorrectly assigned subjects along with 11 random, correctly assigned subjects for a validation check, accurately re-assigned 9 of 14 previously incorrect phenotypes, suggesting initial plate to plate variability since all ELISA plates were made fresh for each run. Previously correctly assigned subjects, 11 of 11, remained correctly assigned. Comparing specific phenotypes revealed VWF:IbCo/VWF:Ag is good at separating type 1C from 2A; ROC area under the curve 0.875, with an optimal ratio threshold 0.649 (sensitivity 0.969, specificity 0.611, p<0.001) and excellent at separating type 2B from type 1; ROC area under the curve 0.978 with a ratio threshold 1.268 (sensitivity 1.000, specificity 0.864, p<0.001), but was poor at separating type 2A from 2M; ROC area under the curve 0.622. VWF:F8B/VWF:Ag was excellent at separating hemophilia A from type 2N; ROC area under the curve 1.000 with a ratio threshold 0.865 (sensitivity 1.000, specificity 1.000, p<0.001). VWF:CB3/VWF:Ag was excellent at separating type 2M from 2A; ROC area under the curve 0.961 with a ratio threshold 0.757 (sensitivity 0.950, specificity 0.889, p<0.001) and excellent at separating type 1C from 2A; ROC area under the curve 0.922 with a ratio threshold 0.597 (sensitivity 1.000, specificity 0.778, p<0.001). Conclusions The rapid VWF functional screening assay is able to discriminate VWD phenotypic variants with good sensitivity and specificity, and may facilitate the rapid laboratory assignment of VWD phenotypes once a subject with low VWF is identified. Disclosures: No relevant conflicts of interest to declare.

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