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/)

An alternative approach to the synthesis of NaB₃H₈ and Na₂B₁₂H₁₂ for solid electrolyte applications

Alkaline or alkaline earth octahydrotriborate M(B3H8)x and dodecahydro-closo-dodecaborate MxB12H12 (M = Li, Na, Mg or Ca with x = 1 or 2) have recently attracted a lot of interest for hydrogen storage and solid electrolyte applications. Nevertheless, their syntheses are still a roadblock for large scale applications. In this paper we propose a novel approach for their syntheses starting from the cheapest borohydride NaBH4. The process involves first the solvothermal synthesis of tetrabutylammonium octahydrotriborate (C4H9)4NB3H8 (TBAB3H8) being the basis for the syntheses of the others boranes. Starting from TBAB3H8, we have synthesized pure and unsolvated NaB3H8 by salt metathesis reaction with sodium tetraphenylborate. Then, we have successfully obtained Na2B12H12 by solvothermal decomposition of NaB3H8. This approach has shown to be quantitative and reproducible, which could lead to the development of these boranes in real life applications

Experimental investigation of Mg(B₃H₈)₂ dimensionality, materials for energy storage applications

Mg(B3H8)2 is a crucial reaction intermediate in the thermal decomposition of the hydrogen storage material Mg(BH4)2 and is discussed as a potential solid-state Mg-ion conductor. We successfully synthesized unsolvated Mg(B3H8)2 and highlight that Mg(B3H8)2 exists mainly as a low-dimensional solid. In addition, the Mg2+ conductivity was evaluated to be 1.4.10−4 S cm−1 at 80 °C

Direct Solution‐Based Synthesis of Na₄(B₁₂H₁₂)(B₁₀H₁₀) Solid Electrolyte

All‐solid‐state batteries (ASSBs) promise higher power and energy density than batteries based on liquid electrolytes. Recently, a stable 3 V ASSB based on the super ionic conductor (1 mS cm−1 near room temperature) Na4(B12H12)(B10H10) has demonstrated excellent cycling stability. This study concerns the development of a five‐step, scalable, and solution‐based synthesis of Na4(B12H12)(B10H10). The use of a wet chemistry approach allows solution processing with high throughput and addresses the main drawbacks for this technology, specifically, the limited electrode–electrolyte contact and high cost. Moreover, a cost‐efficient synthesis of the expensive precursors Na2B10H10 and Na2B12H12 is also achieved through the same process. The mechanism of the reactions is investigated and two key parameters to tune the kinetics and selectivity are highlighted: the choice of counter cation (tetraethylammonium) and solvent

Study of the Temperature- and Pressure-Dependent Structural Properties of Alkali Hydrido closo-borate Compounds

In this work we report on the structural properties of alkali hydrido-closo-(car)borates, a promising class of solid-state electrolyte materials, using high-pressure and temperature dependent X-ray diffraction experiments combined with DFT calculations. The mechanical properties are determined from pressure dependent diffraction studies and DFT calculations; the shear moduli appear to be very low for all studied compounds revealing their high malleability (that can be beneficial for the manufacturing and stable cycling of all-solid-state batteries). The thermo-diffraction experiments also reveal a high coefficient of thermal expansion for these materials. We discover a pressure induced phase transition for K2B12H12 from Fm-3 to Pnnm symmetry around 2GPa. A temperature induced phase transition for Li2B10H10 was also observed for the first time by thermodiffraction and the crystal structure solved combining experimental data and DFT calculations. Interestingly, all phases of the studied compounds (including newly discovered high pressure and high temperature phases) may related via group-subgroup relationship, with the notable exception of the room temperature phase of Li2B10H10

Pressure-induced phase transitions in Na2B12H12, structural investigation on a candidate for solid-state electrolyte

closo-Borates, such as Na2B12H12, are an emerging class of ionic conductors that show promising chemical, electrochemical and mechanical properties as electrolytes in all-solid-state batteries. Motivated by theoretical predictions, high-pressure in situ powder X-ray diffraction on Na2B12H12 was performed and two high-pressure phases are discovered. The first phase transition occurs at 0.5 GPa and it is persistent to ambient pressure, whereas the second transition takes place between 5.7 and 8.1 GPa and it is fully reversible. The mechanisms of the transitions by means of group theoretical analysis are unveiled. The primary order parameters are identified and the stability at ambient pressure of the first polymorph is explained by density functional theory calculations. Finally, the parameters relevant to engineer and build an all-solid-state battery, namely, the bulk modulus and the coefficient of the thermal expansion are reported. The relatively low value of the bulk modulus for the first polymorph (14 GPa) indicates a soft material which allows accommodation of the volume change of the cathode during cycling

Thermal Conversion of Unsolvated Mg(B₃H₈)₂ to BH₄^– in the Presence of MgH₂

In the search for energy storage materials, metal octahydrotriborates, M(B3H8)n, n=1,2, are promising candidates for applications such as stationary hydrogen storage and all solid-state batteries. Therefore, we studied the thermal conversion of unsolvated Mg(B3H8)2 to BH4-: as synthesized, and in the presence of MgH2. The conversion of our unsolvated Mg(B3H8)2 starts at ~100˚C and yields ~22 wt% of BH4- along with the formation of (closo-hydro)borates and volatile boranes. This loss of boron (B) is a sign of poor cyclability of the system. However, the addition of activated MgH2 to unsolvated Mg(B3H8)2 drastically increases the thermal conversion to 85-88wt% of BH4- while simultaneously decreasing the amounts of B-losses. Our results strongly indicate that the presence of activated MgH2 substantially decreases the formation of (closo-hydro)borates and provides the necessary H2 for the B3H8-to-BH4 conversion. This is the first report of a metal octahydrotriborate system to selectively convert to BH4- under moderate conditions of temperature (200 °C) in less than 1h, making the MgB3H8-MgH2 system very promising for energy storage applications

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome Associated with COVID-19: An Emulated Target Trial Analysis

International audienc

Characteristics, management, and prognosis of elderly patients with COVID-19 admitted in the ICU during the first wave: insights from the COVID-ICU study

International audienceBackground: The COVID-19 pandemic is a heavy burden in terms of health care resources. Future decision-making policies require consistent data on the management and prognosis of the older patients (&gt; 70 years old) with COVID-19 admitted in the intensive care unit (ICU). Methods: Characteristics, management, and prognosis of critically ill old patients (&gt; 70 years) were extracted from the international prospective COVID-ICU database. A propensity score weighted-comparison evaluated the impact of intubation upon admission on Day-90 mortality. Results: The analysis included 1199 (28% of the COVID-ICU cohort) patients (median [interquartile] age 74 [72–78] years). Fifty-three percent, 31%, and 16% were 70–74, 75–79, and over 80 years old, respectively. The most frequent comorbidities were chronic hypertension (62%), diabetes (30%), and chronic respiratory disease (25%). Median Clinical Frailty Scale was 3 (2–3). Upon admission, the PaO2/FiO2 ratio was 154 (105–222). 740 (62%) patients were intubated on Day-1 and eventually 938 (78%) during their ICU stay. Overall Day-90 mortality was 46% and reached 67% among the 193 patients over 80 years old. Mortality was higher in older patients, diabetics, and those with a lower PaO2/FiO2 ratio upon admission, cardiovascular dysfunction, and a shorter time between first symptoms and ICU admission. In propensity analysis, early intubation at ICU admission was associated with a significantly higher Day-90 mortality (42% vs 28%; hazard ratio 1.68; 95% CI 1.24–2.27; p &lt; 0·001). Conclusion: Patients over 70 years old represented more than a quarter of the COVID-19 population admitted in the participating ICUs during the first wave. Day-90 mortality was 46%, with dismal outcomes reported for patients older than 80 years or those intubated upon ICU admission

Benefits and risks of noninvasive oxygenation strategy in COVID-19: a multicenter, prospective cohort study (COVID-ICU) in 137 hospitals

International audienceAbstract Rational To evaluate the respective impact of standard oxygen, high-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) on oxygenation failure rate and mortality in COVID-19 patients admitted to intensive care units (ICUs). Methods Multicenter, prospective cohort study (COVID-ICU) in 137 hospitals in France, Belgium, and Switzerland. Demographic, clinical, respiratory support, oxygenation failure, and survival data were collected. Oxygenation failure was defined as either intubation or death in the ICU without intubation. Variables independently associated with oxygenation failure and Day-90 mortality were assessed using multivariate logistic regression. Results From February 25 to May 4, 2020, 4754 patients were admitted in ICU. Of these, 1491 patients were not intubated on the day of ICU admission and received standard oxygen therapy (51%), HFNC (38%), or NIV (11%) ( P < 0.001). Oxygenation failure occurred in 739 (50%) patients (678 intubation and 61 death). For standard oxygen, HFNC, and NIV, oxygenation failure rate was 49%, 48%, and 60% ( P < 0.001). By multivariate analysis, HFNC (odds ratio [OR] 0.60, 95% confidence interval [CI] 0.36–0.99, P = 0.013) but not NIV (OR 1.57, 95% CI 0.78–3.21) was associated with a reduction in oxygenation failure). Overall 90-day mortality was 21%. By multivariable analysis, HFNC was not associated with a change in mortality (OR 0.90, 95% CI 0.61–1.33), while NIV was associated with increased mortality (OR 2.75, 95% CI 1.79–4.21, P < 0.001). Conclusion In patients with COVID-19, HFNC was associated with a reduction in oxygenation failure without improvement in 90-day mortality, whereas NIV was associated with a higher mortality in these patients. Randomized controlled trials are needed