Transfusion massive et coagulopathie-: physiopathologie et implications cliniques

Purpose: To review the pathophysiology of coagulopathy in massively transfused, adult and previously hemostatically competent patients in both elective surgical and trauma settings, and to recommend the most appropriate treatment strategies. Methods: Medline was searched for articles on "massive transfusion,” "transfusion,” "trauma,” "surgery,” "coagulopathy” and "hemostatic defects.” A group of experts reviewed the findings. Principal findings: Coagulopathy will result from hemodilution, hypothermia, the use of fractionated blood products and disseminated intravascular coagulation. The clinical significance of the effects of hydroxyethyl starch solutions on hemostasis remains unclear. Maintaining a normal body temperature is a first-line, effective strategy to improve hemostasis during massive transfusion. Red cells play an important role in coagulation and hematocrits higher than 30% may be required to sustain hemostasis. In elective surgery patients, a decrease in fibrinogen concentration is observed initially while thrombocytopenia is a late occurrence. In trauma patients, tissue trauma, shock, tissue anoxia and hypothermia contribute to the development of disseminated intravascular coagulation and microvascular bleeding. The use of platelets and/or fresh frozen plasma should depend on clinical judgment as well as the results of coagulation testing and should be used mainly to treat a clinical coagulopathy. Conclusions: Coagulopathy associated with massive transfusion remains an important clinical problem. It is an intricate, multifactorial and multicellular event. Treatment strategies include the maintenance of adequate tissue perfusion, the correction of hypothermia and anemia, and the use of hemostatic blood products to correct microvascular bleeding. Objectif: Revoir la physiopathologie de la coagulopathie chez les adultes transfusés massivement et auparavant compétents sur le plan hémostatique, à la fois dans le contexte ďune intervention chirurgicale réglée ou à la suite ďun traumatisme. Recommander les stratégies thérapeutiques les plus appropriées. Méthode: Dans Medline, nous avons cherché les articles traitant de "massive transfusion,” "transfusion,” "trauma,” "surgery,”"coagulopathy” et "hemostatic defects.” Un groupe ďexperts a examiné les résultats. Constatations principales: La coagulopathie résulte de ľhémodilution, ľhypothermie, ľusage de produits sanguins fractionnés et la coagulation intravasculaire disséminée. La portée clinique des effets des solutions ďhydroxyéthyl-amidon sur ľhémostase n'est toujours pas claire. Le maintien ďune température corporelle normale est une stratégie de première intention efficace pour améliorer ľhémostase pendant la transfusion massive. Les globules rouges sont importants dans la coagulation et des hématocrites supérieurs è 30 % pourraient être nécessaires à une hémostase adéquate. Chez les patients en chirurgie réglée, une baisse de la concentration de fibrinogène est observée précocement tandis que la thrombocytopénie est plus tardive. Chez les traumatisés, le trauma tissulaire, le choc, ľanoxie et ľhypothermie tissulaires contribuent au développement ďune coagulation intravasculaire disséminée et du saignement microvasculaire. Ľutilisation de plaquettes et/ou de plasma frais congelé dépendra du jugement du clinicien ainsi que des résultats des tests de coagulation. La transfusion devra surtout viser le traitement ďune coagulopathie clinique (saignement microvasculaire). Conclusion: La coagulopathie associée à la transfusion massive demeure un important problème clinique. C'est un événement complexe, multifactoriel et multicellulaire. Le traitement comprend le maintien ďune perfusion tissulaire adéquate, la correction de ľhypothermie et de ľanémie et ľusage de produits sanguins hémo-statiques pour corriger le saignement microvasculair

On the geometry of bifurcation currents for quadratic rational maps

to appear in Ergodic Th. and Dyn. Syst.International audienceWe describe the behaviour at infinity of the bifurcation current in the moduli space of quadratic rational maps. To this purpose, we extend it to some closed, positive (1, 1)-current on a two-dimensional complex projective space and then compute the Lelong numbers and the self-intersection of the extended current

Simultaneous off-the-grid learning of mixtures issued from a continuous dictionary

In this paper we observe a set, possibly a continuum, of signals corrupted by noise. Each signal is a finite mixture of an unknown number of features belonging to a continuous dictionary. The continuous dictionary is parametrized by a real non-linear parameter. We shall assume that the signals share an underlying structure by assuming that each signal has its active features included in a finite and sparse set. We formulate regularized optimization problem to estimate simultaneously the linear coefficients in the mixtures and the non-linear parameters of the features. The optimization problem is composed of a data fidelity term and a $(\ell_1,L^p)$-penalty. We call its solution the Group-Nonlinear-Lasso and provide high probability bounds on the prediction error using certificate functions. Following recent works on the geometry of off-the-grid methods, we show that such functions can be constructed provided the parameters of the active features are pairwise separated by a constant with respect to a Riemannian metric.When the number of signals is finite and the noise is assumed Gaussian, we give refinements of our results for $p=1$ and $p=2$ using tail bounds on suprema of Gaussian and $\chi^2$ random processes. When $p=2$, our prediction error reaches the rates obtained by the Group-Lasso estimator in the multi-task linear regression model. Furthermore, for $p=2$ these prediction rates are faster than for $p=1$ when all signals share most of the non-linear parameters

Gas-phase electronic spectroscopy of cold molecular cations of astrophysical interest

This thesis, which is the core of a project started in 2010, is aimed at developing an experimental technique suitable for the measurement of the electronic spectra of cold, large, gas-phase molecular cations. Two approaches were initially targeted: photoinduced charge transfer and photodissociation of ionic complexes with He atoms. Since the latter is both the simplest of the two and a universal method, most efforts would be put toward its implementation. The project included the design and assembly of a new apparatus, a tandem mass spectrometer centered on a 22-pole trap. When this thesis was initiated, the apparatus was partially assembled and as a first major task, the assembly had to be completed and characterized. For this reason, chapters 4 and 6 treat some aspects of the obtained electronic spectra that are not novel, but which are part of the characterization of the apparatus and the method. Chapter 2 presents the several types of spectroscopic features that prove that large molecules do form interstellar and circumstellar media. Observations and laboratory experiments are used to put constraints on the responsible molecules. The experimental apparatus and the procedure to obtain the electronic spectra are detailed in Chapter 3, and some aspects of the characterization of the apparatus are presented in Chapter 4. The electronic spectra of several gas-phase protonated H+PAHs at a rotational temperature of 10K constituted the first results of this apparatus and are presented in Chapter 5. These molecules were not studied with one of the two targeted methods, however, they were the firsts spectra obtained in the gas phase for such large cations for astronomical comparison. Also studying these five H+PAHs allowed us to get a better handling of the setup and to solve experimental issues, as shown in Chapter 6. Chapter 7 presents the first results obtained using one of the targetted methods, the electronic spectra of coronene+ and corannulene+, extrapolated from the photodissociation (PD) spectra of their complexes with He. Chapter 8 addresses the case of protonated C60, a project which has merely been started. Finally, Chapter 9 concludes and gives an outlook about the general challenge of identifying large molecules in the ISM and CSEs

Influence of C-reactive protein on thrombin generation assay

To the editors, A close association between inflammatory state,C-reactive protein (CRP) and thromboembolic eventshas been described at least a decade ago [1] but hasresurfaced recently with the outbreak of the severe acuterespiratory syndrome coronavirus 2 (SARS-CoV-2) [...

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

Quartic Parameters for Acoustic Applications of Lattice Boltzmann Scheme

Using the Taylor expansion method, we show that it is possible to improve the lattice Boltzmann method for acoustic applications. We derive a formal expansion of the eigenvalues of the discrete approximation and fit the parameters of the scheme to enforce fourth order accuracy. The corresponding discrete equations are solved with the help of symbolic manipulation. The solutions are explicited in the case of D3Q27 lattice Boltzmann scheme. Various numerical tests support the coherence of this approach.Comment: 23 page