scholarly journals A modified microchip-based flow chamber system for evaluating thrombogenicity in patients with thrombocytopenia

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Bengo Atari ◽  
Takashi Ito ◽  
Tomoka Nagasato ◽  
Tomoko Ohnishi ◽  
Kazuya Hosokawa ◽  
...  
Keyword(s):  
Major Bleeding ◽  
Platelet Transfusion ◽  
Thrombus Formation ◽  
Flow Chamber ◽  
University Hospital ◽  
Minor Bleeding ◽  
Chamber System ◽  
Occlusion Time ◽  
Function Tests ◽  
Thrombogenic Potential

Abstract Background In the intensive care unit (ICU), patients with thrombocytopenia are at high risk for bleeding and should be assessed for their thrombogenic potential. However, the analytical conditions of conventional hemostatic tests are unsuitable for the evaluation of low-platelet samples. Here we aimed to establish suitable analytical conditions with the Total Thrombus-formation Analysis System (T-TAS) for quantitative assessment of thrombogenic potential in patients with thrombocytopenia and to investigate how T-TAS values relate to bleeding symptoms and the effects of platelet transfusion. Methods Modified chips with a different chamber depth were developed for the analysis of low-platelet samples in the T-TAS. We included 10 adult patients admitted to the ICU of Kagoshima University Hospital who required platelet transfusion. Patients were divided into major and minor bleeding groups according to their bleeding scale before platelet transfusion. The thrombogenic potential of these patients before and after platelet transfusion was assessed with hemostatic function tests, including rotational thromboelastometry, multiplate aggregometry, and the T-TAS. Results Analysis of low-platelet samples revealed that, compared with the conventional chip (80-μm-deep chamber), the modified chip (50-μm-deep chamber) achieved higher sensitivity in detecting elevation of flow pressure caused by growth of an occlusive thrombus in the T-TAS analytical chamber. All patients in the minor bleeding group retained thrombogenic potential that occluded the modified chip (occlusion time 16.3 ± 3.3 min), whereas most patients in the major bleeding group were unable to occlude the modified chip during the 30-min measurement (P <  0.01). The recovery of thrombogenic potential after platelet transfusion was confirmed with the T-TAS and correlated with the function, rather than the count, of transfused platelets. Among all evaluated parameters in hemostatic function tests, only the T-TAS showed significant differences in occlusion time and area under the curve both between the minor and major bleeding groups and between pre- and post-platelet transfusion. Conclusions We developed a modified microchip-based flow chamber system that reflects the hemostatic function of patients with thrombocytopenia.

A Multi-Centre Prospective Observational Study of Platelet Transfusion Practice in Neonates with Severe Thrombocytopenia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 961-961 ◽  
Author(s):  
Neil Murray ◽  
Sally Ballard ◽  
Angela Casbard ◽  
Mike Murphy ◽  
Irene Roberts ◽  
...  
Keyword(s):  
Observational Study ◽  
Major Bleeding ◽  
Platelet Transfusion ◽  
Transfusion Practice ◽  
Major Haemorrhage ◽  
Study Entry ◽  
Severe Thrombocytopenia ◽  
Minor Bleeding ◽  
Grade 3 ◽  
Platelet Transfusions

Abstract Background: Platelet transfusion practice in neonates is not evidence-based and there is a lack of data relating transfusion to clinical outcome. To inform the design of clinical trials, we conducted a prospective multicentre observational study of platelet transfusion in thombocytopenic neonates to describe: transfusion practice, including reason for transfusion; clinically-related outcomes, including minor and major bleeding and mortality. Methods: Neonates with platelets &lt;60x109/l were studied at 7 UK neonatal intensive care units Mar 05-Jun 06. With parental consent, daily data were collected on minor bleeding (blood staining of oral/nasogastric/endotracheal secretions and stool; microscopic haematuria; petechial rash; oozing from puncture sites - scored 0–7), and major bleeding (intraventricular (IVH), intra-abdominal, pulmonary or renal). Surviving neonates were studied for 7 days or until platelets were ≥60x109/l. Blood counts and all transfusions were directed by the attending neonatologist, with reason for transfusion and its effect on bleeding prospectively documented. Results: 145 of 167 (87%) eligible neonates were enrolled; 123 (85%) were &lt; 37 weeks gestational age (GA), 89 (61%) were male. The study documented 186 episodes of thrombocytopenia (1606 study days) and 309 platelet transfusions given to 91 (63%) neonates. GA, birth weight and age at thrombocytopenic episode were: 27 (24–32) weeks; 825 (675–1370) grams; 5 (2–16) days, respectively [all data median (IQR)]. 21/145 babies (14%) had major IVH (Grade 3/4) at study entry. Platelets (x 109/l) at study entry, and at platelet nadir, and duration of count &lt;60x109/l were: 44 (33–54); 31 (19–42); 2 (1–5) days respectively. In transfused neonates, platelets (x109/l) pre- and post-transfusion, and number of transfusions were: 27 (19–36); 84 (46–138); 2 (1–4) respectively. The principal indications for transfusion were:- platelet count below threshold of unit guideline: 265/309 (86%); deteriorating clinical condition: 17/309 (6%); and significant bleeding: 7/309 (2%). At least 1 episode of minor bleeding was recorded on 622/1606 (39%) of study days. Minor bleeding scores recorded for 12 hours pre- and post each transfusion were [median (IQR)]: 1 (0–2) and 0 (0–1) respectively. New or extension of IVH bleeding to Grade 3/4 occurred in 7 neonates and other major haemorrhage in 9 neonates (4 pulmonary, 3 GI). A total of 20/145 (14%) neonates died, 13 with major IVH bleeding (of which 10 had Grade 3/4 IVH at study entry); all received platelet transfusions [total 87; median 3 (2 to 7). Conclusion: This study confirms that most neonates with severe thrombocytopenia are preterm, most episodes develop after 72 hours of life (median 5 days) and are of short duration (median 2 days). Minor haemorrhage is common and may be reduced by platelet transfusion. Major haemorrhage is uncommon (11%), is associated with mortality (82%) and affected patients receive a large number of platelet transfusions. There is a clear distinction between the majority of thrombocytopenic neonates who receive one or two transfusions as prophylaxis with a good outcome, and the minority who suffer adverse outcomes despite transfusion. Many neonates are transfused with platelets at thresholds below those suggested in guidelines without apparent clinical detriment. These data will be invaluable for planning the randomised trials necessary for rationalising platelet transfusion in these vulnerable patients.

scholarly journals A microchip flow-chamber system for quantitative assessment of the platelet thrombus formation process

2012 ◽  
Vol 83 (2) ◽  
pp. 154-161 ◽  
Author(s):  
Kazuya Hosokawa ◽  
Tomoko Ohnishi ◽  
Masashi Fukasawa ◽  
Taro Kondo ◽  
Hisayo Sameshima ◽  
...  
Keyword(s):  
Formation Process ◽  
Quantitative Assessment ◽  
Thrombus Formation ◽  
Flow Chamber ◽  
Chamber System ◽  
Platelet Thrombus

Combined Dabigatran and Antiplatelet Agents Assessed by the Novel Microchip-Based Flow Chamber System

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1167-1167
Author(s):  
Kenichi Tanaka ◽  
Kazuya Hosokawa ◽  
Tomoko Ohnishi ◽  
Hisayo Sameshima ◽  
Takehiko Koide ◽  
...  
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Antiplatelet Agents ◽  
Lag Time ◽  
Flow Chamber ◽  
Chamber System ◽  
Shear Rates ◽  
Antithrombotic Effects ◽  
Flow Pressure

Abstract Abstract 1167 Evaluation of the overall antithrombotic activity of dabigatran in combination with antiplatelet agents is difficult because plasma-based clotting for dabigatran, and platelet aggregometry in anticoagulated blood are two separate tests which do not reflect physiological interactions between soluble factors and platelets. The use of a flow chamber could be more suitable in evaluating a flow-dependent platelet activation and coagulation responses. The aim of the current study was to comparatively evaluate antithrombotic effects of dabigatran in combination with dual antiplatelet therapy (aspirin plus P2Y12 blockade) using the microchip-based flow chamber (T-TAS, Fujimori Kogyo, Japan)(1), and thrombin generation (TG) assay (Thrombinoscope, Maastricht, the Netherlands)(2). After the local ethics committee approval, blood samples were obtained from consented 5 healthy volunteers in the tubes containing 3.2% sodium citrate. Whole blood samples were mixed with dabigatran (250, 500, 1000 nM), aspirin (100 nM) plus ARC-66096 (P2Y12 inhibitor, 1000 nM) at 25¡C for 10 min. Corn trypsin inhibitor (50 μg/ml) was used to prevent contact activation. The whole blood sample was perfused in the capillary pre-coated with collagen and thromboplastin at the shear rate of 240 or 600 s−1. The process of thrombus formation was monitored by flow pressure increases inside the capillary; (i) lag time before it reaches 10 kPa (T10), (ii) occlusion time (OT) is the lag time before it reaches 80 kPa as thrombus completely occludes the capillary, and (iii) AUC30 is an area under the flow pressure curve (under 80 kPa) after 30 min of perfusion. For TG assay, platelet-rich plasma (platelet count 150 × 103/μl) was prepared from citrated whole blood. TG was triggered by adding 20 μl of CaCl2-fluorogenic substrate buffer to 80 μl of the sample mixed with tissue factor (1 pM) in each well. The lag time (min), and peak thrombin concentration (nM) were evaluated. In the flow chamber, dabigatran inhibited white thrombus formation in a concentration dependent manner at shear rates of 240 and 600 s−1(Fig. 1). At 500 nM of dabigatran, OT was prolonged by ∼2-fold from the (non-treated) control at both shear rates. The combination of aspirin and AR-C66096 only weakly suppressed thrombus formation, but it enhanced the antithrombotic efficacy of dabigatran at both shear rates (Fig. 1). In TG measurements using platelet-rich plasma, dabigatran at 500 nM prolonged the by 3.17-fold, and reduced the peak by 57.6% compared to the untreated control (Table 1). Aspirin and AR-C66096 weakly prolonged the lag time without affecting the peak height. There were relatively small changes in these parameters when antiplatelet agents were combined with dabigatran (Table 1). Our results suggest that combined antithrombotic effects of dabigatran, aspirin, and P2Y12inhibition can be demonstrated in the whole blood using the flow chamber system compared without additional plasma preparation required for TG assay. The re-calcified whole blood was perfused at the shear rate of 240 s−1 or 600 s−1. Asp/AR-C=aspirin and AR-C66096 Table 1. Lag time (min) Peak (nM) Native Asp/AR-C Native Asp/AR-C Control 6.8 ± 0.8 9.4 ± 3.2 92.1 ± 23.7 91.2 ± 29.5 Dabi 250 nM 18.6 ± 5.4 21.1 ± 4.5 69.3 ± 20.6 52.2 ± 13.6 Dabi 500 nM 21.6 ± 5.3 26.2 ± 10.2 53.0 ± 5.8 47.8 ± 9.1 Dabi 1000 nM 30.2 ± 5.6 35.1 ± 6.3 23.0 ± 6.9 22.0 ± 8.4 Dabi=dabigatran, Native=no antiplatelet agents, Asp/AR-C=aspirin and AR-C66096 Disclosures: Hosokawa: Fujimori Kogyo: Employment. Ohnishi:Fujimori Kogyo: Employment. Sameshima:Fujimori Kogyo: Employment.

scholarly journals Decreased Platelet Thrombus Size, Due to a Heightened Proteolysis of VWF By ADAMTS13, Is Quickly Restored after Valve Replacement in Aortic Stenosis Patients

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2857-2857
Author(s):  
Hideo Yagi ◽  
Masaki Hayakawa ◽  
Naoko Yamaguchi ◽  
Keigo Yamashita ◽  
Shigeki Taniguchi ◽  
...  
Keyword(s):  
Shear Stress ◽  
Aortic Valve ◽  
Valve Replacement ◽  
Thrombus Formation ◽  
Flow Chamber ◽  
High Shear ◽  
Chamber System ◽  
High Shear Stress ◽  
Platelet Thrombus ◽  
Von Willebrand

Abstract Background: The patients with severe aortic-valve stenosis (AS) are often complicated with bleeding episodes. The association between AS and gastrointestinal bleeding due to angiodysplasia is reported as Heyde's syndrome, which is categorized as one of the acquired von Willebrand disease (AVWD) in cardiovascular disorders. An international survey has shown that Type 2A is the common subtype of AVWD in the patients with AS. AVWD Type 2A is characterized by impaired platelet-dependent VWF function caused by marked decrease or absence of the most hemostatically active HMW-VWFM. In the patients with AS, a significant correlation between the increased high shear stress and loss of HMW-VWFM in vivo. Further, the absence of HMW-VWFM and bleeding tendency are normalized after valve replacement. These results suggest that enhanced proteolysis of von Willebrand factor (VWF) as it passes through the stenotic valve may induce the loss of HMW-VWFM because high shear stress can induce structure changes in VWF, which is sensitive form to the VWF cleaving protease, termed ADAMTS13. Here, we performed investigation of plasma levels of VWF antigen (VWF:Ag), ADAMTS13 activity (ADAMTS13:AC), and platelet thrombus formation in the patients with AS by valve replacement to confirm the pathophysiological mechanism of this rare disease. Patients and Methods: Ten consecutive patients who underwent aortic valve replacement for AS in Nara Medical University Hospital were enrolled in this study. The severity of AS was judged by the American Heart Association guideline. All patients had no bleeding history and received bovine tissue valves replacement followed by administration of warfarin and/or anti-platelet agents for prevention of thrombosis a week after surgery. We collected a series of blood samples from these patients before and day1, 8, 15, 22 after valve replacement. Excluding one patient who developed critical cardiac failure just after valve replacement, 9 patients were eventually evaluated by analyses of VWF:Ag, VWF multimers, ADAMTS13:AC, and mural thrombus formation using flow chamber system. VWF:Ag was measured by sandwich ELISA using a rabbit anti-human VWF polyclonal antiserum. Analysis of VWF multimers was performed according to the method of Ruggeri and Zimmerman. ADAMTS13:AC was measured by a chromogenic ADAMTS13-act-ELISA. Platelet thrombus formation was evaluated by thrombus generation under a high shear stress in a parallel plate flow chamber system. Briefly, whole blood anti-coagulated with argatroban was incubated with the fluorescent dye DiOC6 (1uM), and these samples containing DiOC6 -labeled platelets were perfused for 7 min over a type I collagen-coated glass surface under a high shear rate (1500 s-1). The DiOC6 fluorescence corresponding to the platelets was examined at an excitation wavelength of 488 nm with a barrier filter at 500 nm. The percentage of the area covered by adhering platelets (surface coverage) and each thrombus volume were evaluated. Results: Plasma levels of VWF:Ag before surgery were 78.1 % (median) and those on day 1, 8, 15, 22 after surgery were 130, 224, 155, and 134 %, respectively (Fig 1). Conversely, these levels of ADAMTS13:AC were 50.5, 35.5, 25.5, 25.1, and 30.3 %, respectively (Fig 2). The ratio of VWF:Ag/ADAMTS13:AC at before and day 1, 8, 15, 22 after surgery were 1.6, 4.5, 8.1, 6.1, and 4.1, respectively. In VWF multimer analysis, we found the obvious defect of HMW-VWFM in 7 of 9 patients before surgery, who were diagnosed with severe AS. The remaining two patients had moderate AS with the slight defect of HMW-VWFM. These defects were improved within 14 days after surgery. In platelet thrombus formation, the amount of thrombus volumes significantly increased at day 8, 15, and 22 after compared with before surgery (Fig 3). Conclusion: The dramatic recovery of platelet thrombus formation was observed in the patients with AS by valve replacement. The rapid increment of VWF and normalization of VWFM pattern, together with reduction of ADAMTS13 after valve replacement suggested heightened proteolysis of VWF by ADAMTS13 under high shear stress would be a major cause of this unique bleeding complication. The highest ratio of VWF:Ag/ADAMTS13:AC at day 8 after surgery might imply the necessity of blockade of heightened VWF function with anti-platelet agents. Figure 1 Figure 1. Disclosures Matsumoto: Alfresa Pharma Corporation: Patents & Royalties. Fujimura:Alfresa Pharma Corporation: Patents & Royalties.

Assessment of bleeding incidences associated with rivaroxaban therapy in adults with solid tumors

2018 ◽  
Vol 25 (1) ◽  
pp. 192-197
Author(s):  
Kellie J Weddle ◽  
Patrick J Kiel ◽  
Parth J Patel
Keyword(s):  
Prostate Cancer ◽  
Solid Tumors ◽  
Major Bleeding ◽  
Solid Tumor ◽  
Renal Cell ◽  
Anticoagulation Therapy ◽  
University Hospital ◽  
Cancer Center ◽  
Minor Bleeding ◽  
Cancer Types

Purpose Report bleeding incidences associated with rivaroxaban in adult patients with solid tumor malignancies requiring anticoagulation therapy. Methods This retrospective review was conducted at Indiana University Health, University Hospital and the Simon Cancer Center in Indianapolis, IN from January 2013 – February 2016. Patients were included if they had a solid tumor malignancy and prescribed rivaroxaban. Data were collected on 144 patients. Major bleeding was defined as bleeding requiring treatment (local, systemic treatment, blood cell transfusions) or hospitalization and minor bleeding was defined as bleeding not requiring treatment or hospitalization. Results Sixty-four (44%) patients experienced bleeding while on rivaroxaban. There were six cancer types that had a higher incidence of bleeding: bladder, breast, melanoma, pancreas, prostate, and renal cell cancers; 40% (6/15) of patients with bladder cancer experienced bleeding; 54% (7/13) with breast cancer experienced bleeding; 40% (4/10) of patients with melanoma experienced bleeding; 58% (11/19) of patients with pancreatic cancer experienced bleeding; 45% (10/22) of patients with prostate cancer experienced bleeding; and 56% (5/9) of patients with renal cell carcinoma experienced bleeding. No other data collected identified increased incidence of bleeding. Conclusions Patients on rivaroxaban with a diagnosis of bladder, breast, melanoma, pancreas, prostate, or renal cell cancers had a higher incidence of bleeding compared to other solid tumors. Major bleeding was higher in bladder, breast, pancreas, and renal cell carcinomas, while minor bleeding was higher in patients with melanoma and prostate cancer.

scholarly journals Assessment of Platelet Thrombus Formation under Flow Conditions in Adult Patients with COVID-19: An Observational Study

2021 ◽  
Author(s):  
Andrea Artoni ◽  
Mauro Panigada ◽  
Stefano Ghirardello ◽  
Anna Lecchi ◽  
Stefano Aliberti ◽  
...  
Keyword(s):  
Thrombus Formation ◽  
Flow Chamber ◽  
Illness Severity ◽  
Pressure Curve ◽  
Start Time ◽  
Occlusion Time ◽  
Group A ◽  
Platelet Thrombus ◽  
Analysis System ◽  
Group B

Abstract Background Coronavirus disease 2019 (COVID-19) is associated with systemic inflammation, which may dysregulate platelet function. Total Thrombus-Formation Analysis System (T-TAS) is a flow-chamber device that analyses platelet-mediated thrombus formation in capillary channels through the following parameters: (1) the area under the flow-pressure curve (AUC), (2) occlusion start time (OST), time needed to reach OST, and (3) occlusion time (OT), time needed to reach the occlusion pressure. Methods and Findings Sixty-one COVID-19 patients admitted to intensive, subintensive, and low intensive care were prospectively enrolled according to the time of admission: group A (up to 8 days) (n = 18); group B (from 9 to 21 days) (n = 19), and group C ( > 21 days) (n = 24). T-TAS measurements were performed at enrolment and after 7 days. Median OST was similar among groups. AUC was lower in group A compared to B (p = 0.001) and C (p = 0.033). OT was longer in group A compared to B (p = 0.001) and C (p = 0.028). Platelet count (PC) was higher in group B compared to A (p = 0.024). The linear regression showed that OT and AUC were independent from PC in group A (OT: 0.149 [95% confidence interval [CI]: –0.326 to 0.624], p = 0.513 and AUC: 0.005 [95% CI: –0.008 to 0.017], p = 0,447). In contrast, in group B, PC was associated with OT (–0.019 [–0.028 to 0.008], p = 0.023) and AUC (0.749 [0.358–1.139], p = 0,015), similarly to group C. Conversely, patients with different illness severity had similar T-TAS parameters. Conclusion COVID-19 patients display an impaired platelet thrombus formation in the early phase of the disease compared to later stages and controls, independently from illness severity.

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