44 research outputs found
Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.
RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 â„60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Etude de la formation de réseaux polyuréthane au sein de films multicouches
Magnetic tapes are multilayer assemblies using polyurethane networks. These organic materials are used as a protective coating containing pigments or as a binder ensuring the cohesion of the magnetic charges used for the information coding. Among the defects, the appearance of which requires a better chemical reactions involved in these assemblies development understanding, an excessive adhesion development between the strips and PVC plates which can lead to degradation by tearing been targeted for this study.The reaction conditions influence (atmosphere, temperature and alcohol / isocyanate molar ratios) on the crosslinking kinetics of model polyurethane systems made it possible to quantify the residual reactive species at the network formation end and to prove the isocyanate functions involvement in side reactions, and their reactivity inhibition when the reactions are not conducted under inert conditions. The water presence in the reaction environment was related to the isocyanate functions involvement in the urea bonds formation. Finally, the model assemblies realization did not make it possible to reproduce the stripping but the assemblies provided by the industrialist study suggests that the process used for the protective layer shaping is the defect cause.Les bandes magnĂ©tiques sont des assemblages multicouches utilisant des rĂ©seaux polyurĂ©thanes. Ces matĂ©riaux organiques sont utilisĂ©s en tant que revĂȘtement protecteur contenant des pigments ou en tant que liant assurant la cohĂ©sion des charges magnĂ©tiques utilisĂ©es pour le codage dâinformations. Parmi les dĂ©fauts, dont lâapparition nĂ©cessite une meilleure comprĂ©hension des rĂ©actions chimiques mises en jeu lors de lâĂ©laboration de ces assemblages, le dĂ©veloppement dâune adhĂ©sion excessive entre les bandes et des plaques de PVC pouvant conduire Ă une dĂ©gradation par arrachement a Ă©tĂ© ciblĂ© pour cette Ă©tude.Lâinfluence des conditions de rĂ©actions (atmosphĂšre, tempĂ©rature et rapports molaires alcool/isocyanate) sur la cinĂ©tique de rĂ©ticulation de systĂšmes polyurĂ©thanes modĂšles a permis de quantifier les espĂšces rĂ©actives rĂ©siduelles Ă lâissue de la formation du rĂ©seau et de mettre en Ă©vidence lâimplication des fonctions isocyanate dans des rĂ©actions secondaires, et une inhibition de leur rĂ©activitĂ© lorsque les rĂ©actions ne sont pas conduites en conditions inertes. La prĂ©sence dâeau dans le milieu rĂ©actionnel a Ă©tĂ© reliĂ©e lâimplication des fonctions isocyanate dans la formation de liaisons urĂ©e. Enfin, la rĂ©alisation dâassemblages modĂšles nâa pas permis de reproduire les arrachements mais lâĂ©tude dâassemblages fournis par lâindustriel suggĂšre que le procĂ©dĂ© utilisĂ© pour la mise en forme de la couche de protection soit la cause de ce dĂ©faut
Etude de la formation de réseaux polyuréthane au sein de films multicouches
Magnetic tapes are multilayer assemblies using polyurethane networks. These organic materials are used as a protective coating containing pigments or as a binder ensuring the cohesion of the magnetic charges used for the information coding. Among the defects, the appearance of which requires a better chemical reactions involved in these assemblies development understanding, an excessive adhesion development between the strips and PVC plates which can lead to degradation by tearing been targeted for this study.The reaction conditions influence (atmosphere, temperature and alcohol / isocyanate molar ratios) on the crosslinking kinetics of model polyurethane systems made it possible to quantify the residual reactive species at the network formation end and to prove the isocyanate functions involvement in side reactions, and their reactivity inhibition when the reactions are not conducted under inert conditions. The water presence in the reaction environment was related to the isocyanate functions involvement in the urea bonds formation. Finally, the model assemblies realization did not make it possible to reproduce the stripping but the assemblies provided by the industrialist study suggests that the process used for the protective layer shaping is the defect cause.Les bandes magnĂ©tiques sont des assemblages multicouches utilisant des rĂ©seaux polyurĂ©thanes. Ces matĂ©riaux organiques sont utilisĂ©s en tant que revĂȘtement protecteur contenant des pigments ou en tant que liant assurant la cohĂ©sion des charges magnĂ©tiques utilisĂ©es pour le codage dâinformations. Parmi les dĂ©fauts, dont lâapparition nĂ©cessite une meilleure comprĂ©hension des rĂ©actions chimiques mises en jeu lors de lâĂ©laboration de ces assemblages, le dĂ©veloppement dâune adhĂ©sion excessive entre les bandes et des plaques de PVC pouvant conduire Ă une dĂ©gradation par arrachement a Ă©tĂ© ciblĂ© pour cette Ă©tude.Lâinfluence des conditions de rĂ©actions (atmosphĂšre, tempĂ©rature et rapports molaires alcool/isocyanate) sur la cinĂ©tique de rĂ©ticulation de systĂšmes polyurĂ©thanes modĂšles a permis de quantifier les espĂšces rĂ©actives rĂ©siduelles Ă lâissue de la formation du rĂ©seau et de mettre en Ă©vidence lâimplication des fonctions isocyanate dans des rĂ©actions secondaires, et une inhibition de leur rĂ©activitĂ© lorsque les rĂ©actions ne sont pas conduites en conditions inertes. La prĂ©sence dâeau dans le milieu rĂ©actionnel a Ă©tĂ© reliĂ©e lâimplication des fonctions isocyanate dans la formation de liaisons urĂ©e. Enfin, la rĂ©alisation dâassemblages modĂšles nâa pas permis de reproduire les arrachements mais lâĂ©tude dâassemblages fournis par lâindustriel suggĂšre que le procĂ©dĂ© utilisĂ© pour la mise en forme de la couche de protection soit la cause de ce dĂ©faut
Study of polyurethane networks formation within multilayer films
Les bandes magnĂ©tiques sont des assemblages multicouches utilisant des rĂ©seaux polyurĂ©thanes. Ces matĂ©riaux organiques sont utilisĂ©s en tant que revĂȘtement protecteur contenant des pigments ou en tant que liant assurant la cohĂ©sion des charges magnĂ©tiques utilisĂ©es pour le codage dâinformations. Parmi les dĂ©fauts, dont lâapparition nĂ©cessite une meilleure comprĂ©hension des rĂ©actions chimiques mises en jeu lors de lâĂ©laboration de ces assemblages, le dĂ©veloppement dâune adhĂ©sion excessive entre les bandes et des plaques de PVC pouvant conduire Ă une dĂ©gradation par arrachement a Ă©tĂ© ciblĂ© pour cette Ă©tude.Lâinfluence des conditions de rĂ©actions (atmosphĂšre, tempĂ©rature et rapports molaires alcool/isocyanate) sur la cinĂ©tique de rĂ©ticulation de systĂšmes polyurĂ©thanes modĂšles a permis de quantifier les espĂšces rĂ©actives rĂ©siduelles Ă lâissue de la formation du rĂ©seau et de mettre en Ă©vidence lâimplication des fonctions isocyanate dans des rĂ©actions secondaires, et une inhibition de leur rĂ©activitĂ© lorsque les rĂ©actions ne sont pas conduites en conditions inertes. La prĂ©sence dâeau dans le milieu rĂ©actionnel a Ă©tĂ© reliĂ©e lâimplication des fonctions isocyanate dans la formation de liaisons urĂ©e. Enfin, la rĂ©alisation dâassemblages modĂšles nâa pas permis de reproduire les arrachements mais lâĂ©tude dâassemblages fournis par lâindustriel suggĂšre que le procĂ©dĂ© utilisĂ© pour la mise en forme de la couche de protection soit la cause de ce dĂ©faut.Magnetic tapes are multilayer assemblies using polyurethane networks. These organic materials are used as a protective coating containing pigments or as a binder ensuring the cohesion of the magnetic charges used for the information coding. Among the defects, the appearance of which requires a better chemical reactions involved in these assemblies development understanding, an excessive adhesion development between the strips and PVC plates which can lead to degradation by tearing been targeted for this study.The reaction conditions influence (atmosphere, temperature and alcohol / isocyanate molar ratios) on the crosslinking kinetics of model polyurethane systems made it possible to quantify the residual reactive species at the network formation end and to prove the isocyanate functions involvement in side reactions, and their reactivity inhibition when the reactions are not conducted under inert conditions. The water presence in the reaction environment was related to the isocyanate functions involvement in the urea bonds formation. Finally, the model assemblies realization did not make it possible to reproduce the stripping but the assemblies provided by the industrialist study suggests that the process used for the protective layer shaping is the defect cause
Etude des mĂ©canismes rĂ©actionnels intervenant au cours de la formation dâun film polymĂšre multicouche
International audienc
MULTILAYER POLYMER FILMS WITH MAGNETIC PROPERTIES: IMPLEMENTATION AND CHARACTERIZATION
International audienc
Etude des mĂ©canismes rĂ©actionnels intervenant au cours de la formation dâun film polymĂšre multicouche
International audienc
Multilayer Polymer Films with Magnetic Properties: Implementation and Characterization
International audienc