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/)

Modification by hydrogenation of the CeCuSi magnetic behavior

The ternary silicide CeCuSi, that crystallizes in the hexagonal ZrBeSi-type structure, absorbs hydrogen at 393 K and 2 MPa to form the stable hydride..

Various ways including substitution and protection used to improve the cyclability of ‘MgNi' electrodes

Three different treatments have been investigated to improve the cyclability in KOH electrolyte of ‘MgNi' used as hydrogen storage electrode material for Ni–MH batteries. Whereas hydrophobic molecule grafting does not give significant improvement, replacement of Mg by Ti or coating the ‘MgNi' powder with copper in a supercritical CO2–EtOH mixture increase strongly the resistance of the electrode against hydroxylation: the capacity after 12 cycles is 98% higher for ‘Mg0.5Ti0.5Ni' and 45% higher after coating by a thin copper film in comparison with the raw ‘MgNi' material

Relationship between structure and sorption kinetic behaviour for ternary CeMX compounds

The crystal structure and the hydrogenation behaviour of more than 10 ternary compounds based on cerium (i.e. CeMX with M=Mn, Ni, Cu and X=Al, Ga, In, Si, Ge, Sn) is presented. Most of the structures can be described as a stacking of [Ce6] trigonal prisms occupied by a M or a X atom. All these compounds form stable hydrides and the kinetic behaviour can be linked to the H insertion sites and to the structural changes upon hydrogenation. If no structural change is observed during the formation of the hydride and if H atoms occupy [Ce3M] tetrahedral sites, the reaction with hydrogen is fast. But if a structural change occurs during hydrogenation, then, the reaction takes place slowly. Particular behaviour is reported when H atoms occupy (i) [Ce4] tetrahedral sites (slow kinetics without structural change) and (ii) [Ce3Ni2] or [Ce3Si2] bipyramidal sites (high kinetics without a structural change)

Superstructures in room-temperature ordered deuterides CeCuSiDx and CeCuGeDx

Crystallographic superstructures in the deuterides CeCuSiD1.64(5) and CeCuGeH1.15(5) have been characterized by neutron diffraction..

Antiferromagnetic–ferromagnetic transition induced by the hydrogenation of the ternary stannide Ce(Ni0.82Cu0.18)Sn

The title compound absorbs slowly hydrogen at 523 K under a pressure of P(H2)=1 MPa, giving the new hydride Ce(Ni0.82Cu0.18)SnH1.7(1)..

Antiferromagnetic–ferromagnetic transition induced by the hydrogenation of the ternary stannide Ce(Ni0.82Cu0.18)Sn

The title compound absorbs slowly hydrogen at 523 K under a pressure of P(H2)=1 MPa, giving the new hydride Ce(Ni0.82Cu0.18)SnH1.7(1)..

Ordering phenomena in intermetallic CeMX (M=Ni, Cu and X=Si, Ge, Sn) upon hydrogenation

CeMX ternary compounds (M=Ni, Cu and X=Si, Ge, Sn) crystallize in derivative structures of the hexagonal AlB2-type which can be either the hexagonal ZrBeSi- or LiGaGe- type structure, either the orthorhombic TiNiSi-type structure or the tetragonal LaPtSi-type structure depending on M and X. Under hydrogenation, these ternary compounds form stable hydrides. Their crystallographic structure has been investigated by X-ray diffraction and electron transmission microscopy. The structural type of CeNiSiH0.8 remains that of the corresponding initial compound (i.e. the tetragonal LaPtSi-type structure). The hydrogenation only induces an anisotropic variation of the unit cell parameters (a decreases and c increases) without significant increase of the unit cell volume (+0.1%). The two other compounds based on nickel, CeNiGe and CeNiSn, undergo a structural transition during the absorption of hydrogen. The corresponding hydrides, CeNiGeH1.6 and CeNiSnH1.8 crystallize in the hexagonal ZrBeSi-type structure. For the compounds based on copper, no structural transitions are observed. Instead electron diffraction experiments point out the presence of superstructures for CeCuSiH1.3 and CeCuGeH1.0 hydrides. These superstructures reveal the presence of an order between hydrogen and vacancies in the partially occupied (1/3 2/3 z≈0.436 in the ZrBeSi-type structure) site. The volume of the cell corresponding to these superstructures is directly related to the amount of hydrogen atoms in the structure. The c parameter has to be multiplied by 5 for CeCuSiH1.35 compared with the ternary compound while it has only to be multiplied by 3 for the CeCuGeH1.0. The crystallographic evolution resulting from the hydrogenation of CeCuSn is more complex since incommensurate modulation was observed by electron diffraction and confirmed by single crystal X-ray diffraction. A short range ordering, leading to a displacement of heavy atoms takes place in this compound

The ternary gallide CeNiGa: polymorphism and hydrogen absorption

The ternary gallide CeNiGa presents a crystallographic transformation with temperature. The crystal structure of the high-temperature form (HTF), determined for the first time by X-ray diffraction on a single crystal, is orthorhombic TiNiSi-type, whereas the low-temperature form (LTF) adopts the hexagonal ZrNiAl-type. Electrical resistivity and magnetization measurements reveal that both (LTF) and (HTF) CeNiGa are classified as intermediate valence compounds, but their Kondo temperatures TK are strongly different; TK⪢300 K and TK≅95(5) K for (LTF) and (HTF), respectively. Both forms react with hydrogen at room temperature and form the hydride CeNiGaH1.1(1) which crystallizes in the hexagonal AlB2-type with lattice parameters a=4.239(4) Å and c=4.258(5) Å. Hydrogenation also induces a valence transition for cerium from the intermediate valence state (CeNiGa) to a purely trivalent state (CeNiGaH1.1(1)). This behavior is correlated to an increase of the unit cell volume after hydrogenation and is compared to that observed previously for CeNiAlH1.93

Occurence of ferromagnetic transition on hydrogen insertion in the ternary indide CeNiIn

Letter to the editor : The hydride CeNiInH1.8(1) has been studied by magnetization measurements. It exhibits a ferromagnetic behaviour below TC = 6.8(2) K. In other words, the insertion of hydrogen in CeNiIn induces a cerium valence transition from intermediate valence to the trivalent state