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/)

Characterization and prospective analysis of the contribution of the rhizosphere effect to the performance of wheat (Triticum aestivum) in a mixed crop-livestock context

Face aux enjeux sociétaux, environnementaux et d’érosion de la biodiversité, la reconception des systèmes de cultures mobilisant les interactions écologiques en place des intrants est cruciale à développer. L’interface sol-plante présente un intérêt majeur car elle héberge une diversité de processus impliqués dans la nutrition et la santé des plantes. L’effet rhizosphère induit par les plantes est très dynamique, et influencé non seulement par le type de sol ou l’espèce cultivée mais également par les pratiques agricoles. Dans une approche combinant expérimentation et modélisation statistiques par équation structurale, cette thèse a permis de développer des indicateurs de fonctionnement de la rhizosphère du blé (Triticum aestivum var Absalon) au cours du cycle de développement de la plante.La méthodologie appliquée a permis de mettre en avant des effets synergiques de la diversification des cultures au cours de la succession avec le travail réduit du sol afin de promouvoir l’effet rhizosphère. Enfin, ce travail a permis de mettre en évidence un schéma structurel causal commun entre les conditions contrôlées et le terrain grâce à la modélisation par équation structurales. En conclusion, ce travail de thèse menée en collaboration avec les adhérents de trois coopératives permet d’ouvrir des perspectives de conception et d’évaluation des systèmes de cultures agroécologiques à bas intrants basés sur l’effet rhizosphère.Faced with societal and environmental challenges and loss of biodiversity, the redesign of cropping systems mobilizing ecological interactions instead of synthetic inputs is crucial to develop. The soil-plant interface influenced by root activities is of major interest because it harbors a diversity of processes involved in plant nutrition and health. However, the rhizosphere effect induced by plants is very dynamic, and influenced not only by soil type or crop species but also by agricultural practices. In an approach combining experimentation and statistical modeling by structural equations, indicators of rhizosphere functioning in wheat (Triticum aestivum var Absalon) were developped.The applied methodology allowed to put forward synergistic effects of crop diversification during the succession with reduced tillage in order to promote the rhizosphere effect. Finally, we highlighted a common scheme of causal structure between controlled conditions and the field by structural equation modeling that pave the way for further development of rhizosphere indicators. In conclusion, this thesis work carried out in collaboration with the members of three cooperatives opens perspectives for the design and evaluation of low-input agroecological cropping systems

Does crop diversification impact plant-soil interactions?

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A field indicator for rhizosphere effect monitoring in arable soils

International audienceFor the agroecological transition, the rhizosphere is a critical interface for plants to acquire resources and to enhance plant health with limited inputs. In the present study, we developed a new indicator to estimate and monitor the intensity of plant-soil-microbiota interactions under field conditions.A Rhizosphere Effect Indicator (REI) was calculated by comparing individual and aggregated variables of bulk soil to those of the rhizosphere (i.e. soil enzyme activities and nutrient fluxes) every 2 weeks in the fields of three farms along a crop-diversification gradient. The diversity and structure of microbial communities in bulk soil and the rhizosphere in each field were assessed at flowering.The REI revealed statistically distinct dynamics and intensities of rhizosphere functioning among the three farms. Soil enzyme activities contributed more to the rhizosphere effect than nitrate and phosphate fluxes. Molecular analysis distinguished the two soil compartments and all crop-diversification levels. An integrated REI that provided a single value monitored the rhizosphere effect reliably.Methodological limits due to sampling of the rhizosphere under field conditions must be overcome to develop the REI, but the REI can serve as a complementary tool to traditional soil analysis for agroecological cropping system design and evaluation

Extracorporeal membrane oxygenation network organisation and clinical outcomes during the COVID-19 pandemic in Greater Paris, France: a multicentre cohort study

Erratum inCorrection to Lancet Respir Med 2021; published online April 19. https://doi.org/10.1016/S2213-2600(21)00096-5.International audienceBackground: In the Île-de-France region (henceforth termed Greater Paris), extracorporeal membrane oxygenation (ECMO) for severe acute respiratory distress syndrome (ARDS) was considered early in the COVID-19 pandemic. We report ECMO network organisation and outcomes during the first wave of the pandemic.Methods: In this multicentre cohort study, we present an analysis of all adult patients with laboratory-confirmed SARS-CoV-2 infection and severe ARDS requiring ECMO who were admitted to 17 Greater Paris intensive care units between March 8 and June 3, 2020. Central regulation for ECMO indications and pooling of resources were organised for the Greater Paris intensive care units, with six mobile ECMO teams available for the region. Details of complications (including ECMO-related complications, renal replacement therapy, and pulmonary embolism), clinical outcomes, survival status at 90 days after ECMO initiation, and causes of death are reported. Multivariable analysis was used to identify pre-ECMO variables independently associated with 90-day survival after ECMO.Findings: The 302 patients included who underwent ECMO had a median age of 52 years (IQR 45-58) and Simplified Acute Physiology Score-II of 40 (31-56), and 235 (78%) of whom were men. 165 (55%) were transferred after cannulation by a mobile ECMO team. Before ECMO, 285 (94%) patients were prone positioned, median driving pressure was 18 cm H2O (14-21), and median ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen was 61 mm Hg (IQR 54-70). During ECMO, 115 (43%) of 270 patients had a major bleeding event, 27 of whom had intracranial haemorrhage; 130 (43%) of 301 patients received renal replacement therapy; and 53 (18%) of 294 had a pulmonary embolism. 138 (46%) patients were alive 90 days after ECMO. The most common causes of death were multiorgan failure (53 [18%] patients) and septic shock (47 [16%] patients). Shorter time between intubation and ECMO (odds ratio 0·91 [95% CI 0·84-0·99] per day decrease), younger age (2·89 [1·41-5·93] for ≤48 years and 2·01 [1·01-3·99] for 49-56 years vs ≥57 years), lower pre-ECMO renal component of the Sequential Organ Failure Assessment score (0·67, 0·55-0·83 per point increase), and treatment in centres managing at least 30 venovenous ECMO cases annually (2·98 [1·46-6·04]) were independently associated with improved 90-day survival. There was no significant difference in survival between patients who had mobile and on-site ECMO initiation.Interpretation: Beyond associations with similar factors to those reported on ECMO for non-COVID-19 ARDS, 90-day survival among ECMO-assisted patients with COVID-19 was strongly associated with a centre's experience in venovenous ECMO during the previous year. Early ECMO management in centres with a high venovenous ECMO case volume should be advocated, by applying centralisation and regulation of ECMO indications, which should also help to prevent a shortage of resources

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

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