Studies on hemostasis in COVID-19 deserve careful reporting of the laboratory methods, their significance and their limitations

We read with much interest the recent observational study of Nougier et al., which aimed at studying thrombin generation (TG) and fibrinolysis profiles of COVID-19 patients admitted to an intensive care unit (ICU) or to an internal medicine ward and receiving various schemes of prophylactic heparin.[1] They reported that thrombin potential remained within normal range despite heparin and that fibrinolysis was decreased in relation with increased plasminogen activator inhibitor 1 (PAI-1) and thrombin-activatable fibrinolysis inhibitor (TAFI) antigen plasma levels. Using the rotational thromboelastometry (ROTEM) delta device with EXTEM reagents and the addition of 0.625µg/mL tPA (referred to as 'TEM-tPA'), they reported decreased clot lysis in COVID-19 patients, which was more pronounced in patients who presented a thrombotic event, compared to event-free patients

Prothrombotic Hemostasis Disturbances in Patients with Severe COVID-19:Individual daily data

This data article accompanies the manuscript entitled: "Prothrombotic Disturbances of hemostasis of Patients with Severe COVID-19: a Prospective Longitudinal Observational Cohort Study" submitted to by the same authors. We report temporal changes of plasma levels of an extended set of laboratory parameters during the ICU stay of the 21 COVID-19 patients included in the monocentre cohort: CRP, platelet count, prothrombin time; Clauss fibrinogen and clotting factors II, V and VIII levels, D-dimers, antithrombin activity, protein C, free protein S, total and free tissue factor pathway inhibitor, PAI-1 levels, von Willebrand factor antigen and activity, ADAMTS-13 (plasma levels); and of two integrative tests of coagulation (thrombin generation with ST Genesia) and fibrinolysis (global fibrinolytic capacity - GFC). Regarding hemostasis, we used double-centrifuged frozen citrated plasma prospectively collected after daily performance of usual coagulation tests. Demographic and clinical characteristics of patients and thrombotic and hemorrhagic complications were also collected from patient's electronic medical reports

Viscoelastometric Testing to Assess Hemostasis of COVID-19: A Systematic Review

Infection by SARS-CoV-2 is associated with a high risk of thrombosis. The laboratory documentation of hypercoagulability and impaired fibrinolysis remains a challenge. Our aim was to assess the potential usefulness of viscoelastometric testing (VET) to predict thrombotic events in COVID-19 patients according to the literature. We also (i) analyzed the impact of anticoagulation and the methods used to neutralize heparin, (ii) analyzed whether maximal clot mechanical strength brings more information than Clauss fibrinogen, and (iii) critically scrutinized the diagnosis of hypofibrinolysis. We performed a systematic search in PubMed and Scopus databases until 31st December 2020. VET methods and parameters, and patients' features and outcomes were extracted. VET was performed for 1063 patients (893 intensive care unit (ICU) and 170 non-ICU, 44 studies). There was extensive heterogeneity concerning study design, VET device used (ROTEM, TEG, Quantra and ClotPro) and reagents (with non-systematic use of heparin neutralization), timing of assay, and definition of hypercoagulable state. Notably, only 4 out of 25 studies using ROTEM reported data with heparinase (HEPTEM). The common findings were increased clot mechanical strength mainly due to excessive fibrinogen component and impaired to absent fibrinolysis, more conspicuous in the presence of an added plasminogen activator. Only 4 studies out of the 16 that addressed the point found an association of VETs with thrombotic events. So-called functional fibrinogen assessed by VETs showed a variable correlation with Clauss fibrinogen. Abnormal VET pattern, often evidenced despite standard prophylactic anticoagulation, tended to normalize after increased dosing. VET studies reported heterogeneity, and small sample sizes do not support an association between the poorly defined prothrombotic phenotype of COVID-19 and thrombotic events

Performance And Health Of Holstein And Montbéliarde Dairy Cows In Organic Low Inputs Systems

The aim of this study was to compare the performance of Holstein and Montbeliarde dairy cows in a mixed crop dairy system and in a more restricted one, a 100% grazing system and. The total dataset contained data from 970 lactations of cows living in an experimental farm (Mirecourt, France) from 2004 to 2015. Over 44 weeks of lactation, Holstein cows produced more milk (+ 531 kg) and fat and proteins (+ 46 kg) than Montbeliarde cows, which represents a higher milk yield per body weight (+1.04 kg / kg of body weight). However, Holstein cows had poorer reproduction performances mainly in the grazing system (- 25 % of gestation rate) and they decreased to a larger extent their body weight and condition in early lactation. Holstein cows had more reproductive disorders, but Montbeliarde cows faced more lameness. On the whole, cows had more health disorders in the grazing system. Longevity between the two breed was not different because of the choice to keep more frequently Holstein cows in a prolonged lactation. Four profiles of cows were identified in terms of lactation, reproduction, body condition and health, but this classification couldn’t be predicted by their breed, their parity or their feeding constrains

Performance and health of Holstein and Montbéliarde dairy cows in organic systems

International audienceThe aim of this study was to compare the performance of Holstein and Montbeliarde dairy cows in a mixed crop dairy system and in a more restricted one, a 100% grazing system and. The total dataset contained data from 970 lactations of cows living in an experimental farm (Mirecourt, France) from 2004 to 2015. Over 44 weeks of lactation, Holstein cows produced more milk (+ 531 kg) and fat and proteins (+ 46 kg) than Montbeliarde cows, which represents a higher milk yield per body weight (+1.04 kg / kg of body weight). However, Holstein cows had poorer reproduction performances mainly in the grazing system (- 25 % of gestation rate) and they decreased to a larger extent their body weight and condition in early lactation. Holstein cows had more reproductive disorders, but Montbeliarde cows faced more lameness. On the whole, cows had more health disorders in the grazing system. Longevity between the two breed was not different because of the choice to keep more frequently Holstein cows in a prolonged lactation. Four profiles of cows were identified in terms of lactation, reproduction, body condition and health, but this classification couldn’t be predicted by their breed, their parity or their feeding constrains

Are Viscoelastometric Assays of Old Generation Ready for Disposal? Comment on Volod et al. Viscoelastic Hemostatic Assays: A Primer on Legacy and New Generation Devices. <i>J. Clin. Med.</i> 2022, <i>11</i>, 860

With the advent of new viscoelastometric hemostatic assay (VHA) devices, with ready-to-use cartridge reagents allowing for their use by people without special laboratory skills, the appreciation of the actual clinical value of VHAs in settings such as severe trauma, post-partum hemorrhage, cardiac surgery and liver transplantation still needs to be fully validated. While two of the newest versions remain based on a ‘cup and pin’ system (ROTEM® sigma, ClotPro®), two other new devices (TEG® 6s, Quantra®) rely on very different technologies: clotting blood is no longer in contact with the probe and challenged by oscillation of one of the components but explored with ultrasound exposure. A systematic literature search (including Sonoclot®) retrieved 20 observational studies (19 prospective). Most studies pointed to imperfect agreements, highlighting the non-interchangeability of devices. Only a few studies, often with a limited number of patients enrolled, used a clinical outcome. No study compared VHA results with conventional laboratory assays obtained through a rapid tests panel. Clinical evidence of the utility of the new VHAs largely remains to be proven through randomized clinical trials, with clinically relevant outcomes, and compared to rapid panel hemostasis testing. The availability of new, improved VHA devices provides an impetus and an opportunity to do so