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 ≥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/)

Études d'effets systématiques au niveau de 10⁻¹⁸ sur des horloges à réseau optique strontium et applications métrologiques

LNE-SYRTE is currently developing optical lattice clocks. These clocks consist of a set of tens of thousands of ultra-cold atoms confined in an optical lattice, of which a narrow transition, the clock transition, is used to control the frequency of an ultra stable laser. The performances of optical clocks find applications in time-frequency metrology, in geodesychronometry, or in fundamental physics.Two strontium optical lattice clocks are operational at SYRTE, and present an instability of 7e-16 at 1 second, and a fractional inaccuracy of 1.4e-17. The reliability of these instrumentsallows long and regular metrological campaigns, which have confirmed their performance during international campaigns. This thesis proposes a description of the clocks, and their recent improvements. A revised accuracy budget is presented, as well as work contributing to reduce the inaccuracy of some systematic effects at the level of 1e-18: A study of the light shift of the clock transition is proposed, and accompanied by a protocol allowing to get rid of its dependence with thetemperature of the interrogated atoms. The assembly of a new ultra-high vacuum chamber is also presented, in order to reduce the inhomogeneity of the thermal radiation received by the atoms, main contribution of inaccuracy. Numerous results of comparisons of strontium clocks, local and international, by fiber links and satellites, against microwave and optical clocks are also described. It includes the first contributions to the steering of the International Atomic Time (TAI) in real time.Le LNE-SYRTE développe actuellement des horloges à réseau optique. Ces horloges consistent en un ensemble de quelques dizaines de milliers d'atomes ultrafroids confinés dans un réseau optique, dont une transition étroite, la transition d'horloge, est utilisée pour asservir la fréquence d'un laser ultra stable. Les performances des horloges optiques trouvent des applications aussi bien en métrologie temps-fréquences, qu'en géodésiechronométrique, ou encore qu'en physique fondamentale.Deux horloges à réseaux optiques strontium sont opérationnelles au SYRTE, et présentent une instabilité de 7e-16 à 1 seconde, et une inexactitude fractionnaire de 1.4e-17. La fiabilité de ces instruments permet des campagnes métrologiques longues et régulières, qui ont notamment permis de confirmer leur performance lors de campagnes internationales.Cette thèse propose une description des horloges, et de leurs améliorations récentes. Un budget d'exactitude révisé est présenté, ainsi que des travaux contribuant à réduire l'inexactitude de certains effets systématiques au niveau de 1e-18 : Une étude du déplacement lumineux de la transition d'horloge est proposée, et accompagnée d'un protocole permettant de s'affranchir de sa dépendance avec la température des atomes interrogés. On présente également l'assemblage d'une nouvelle enceinte ultra-haut vide, devant réduire l'inhomogénéité du rayonnement thermique reçu par les atomes, principale contribution à l'inexactitude. De nombreux résultats de comparaisons des horloges strontium, locales et internationales, par liens fibrés et par satellites, contre des horloges micro-ondes et optiques sont également décrites. Y figurent la première contribution au pilotage du Temps Atomique Internationale (TAI) en temps réel

La survie des hommes en conditions extrêmes à l'aide des plantes et des champignons

LILLE2-BU Santé-Recherche (593502101) / SudocSudocFranceF

Systematic effects in strontium optical lattice clocks

International audienc

Systematic effects in strontium optical lattice clocks

International audienc

Sr optical lattice clocks at LNE SYRTE: metrology, quantum technologies, and fundamental physics

International audienc

Sr optical lattice clocks at LNE SYRTE: metrology, quantum technologies, and fundamental physics

International audienc

Non-destructive detection system in strontium optical lattice clocks

International audienc

Non-destructive detection in 87Sr optical lattice clocks

International audienc