Relationship between ventilator-associated pneumonia and mortality in COVID-19 patients: a planned ancillary analysis of the coVAPid cohort

Background Patients with SARS-CoV-2 infection are at higher risk for ventilator-associated pneumonia (VAP). No study has evaluated the relationship between VAP and mortality in this population, or compared this relationship between SARS-CoV-2 patients and other populations. The main objective of our study was to determine the relationship between VAP and mortality in SARS-CoV-2 patients. Methods Planned ancillary analysis of a multicenter retrospective European cohort. VAP was diagnosed using clinical, radiological and quantitative microbiological criteria. Univariable and multivariable marginal Cox's regression models, with cause-specific hazard for duration of mechanical ventilation and ICU stay, were used to compare outcomes between study groups. Extubation, and ICU discharge alive were considered as events of interest, and mortality as competing event. Findings Of 1576 included patients, 568 were SARS-CoV-2 pneumonia, 482 influenza pneumonia, and 526 no evidence of viral infection at ICU admission. VAP was associated with significantly higher risk for 28-day mortality in SARS-CoV-2 group (adjusted HR 1.65 (95% CI 1.11-2.46), p = 0.013), but not in influenza (1.74 (0.99-3.06), p = 0.052), or no viral infection groups (1.13 (0.68-1.86), p = 0.63). VAP was associated with significantly longer duration of mechanical ventilation in the SARS-CoV-2 group, but not in the influenza or no viral infection groups. VAP was associated with significantly longer duration of ICU stay in the 3 study groups. No significant difference was found in heterogeneity of outcomes related to VAP between the 3 groups, suggesting that the impact of VAP on mortality was not different between study groups. Interpretation VAP was associated with significantly increased 28-day mortality rate in SARS-CoV-2 patients. However, SARS-CoV-2 pneumonia, as compared to influenza pneumonia or no viral infection, did not significantly modify the relationship between VAP and 28-day mortality

a retrospective multicenter study

Funding This study was supported in part by a grant from the French government through the « Programme Investissement d’Avenir» (I-SITE ULNE) managed by the Agence Nationale de la Recherche (coVAPid project). Prof. Ignacio Martin-Loeches has been supported by SFI (Science Foundation Ireland), Grant number 20/COV/0038. The funders of the study had no role in the study design, data collection, analysis or interpretation, writing of the report or deci sion to submit for publication.BACKGROUND: Ventilator-associated pneumonia (VAP) is common in patients with severe SARS-CoV-2 pneumonia. The aim of this ancillary analysis of the coVAPid multicenter observational retrospective study is to assess the relationship between adjuvant corticosteroid use and the incidence of VAP. METHODS: Planned ancillary analysis of a multicenter retrospective European cohort in 36 ICUs. Adult patients receiving invasive mechanical ventilation for more than 48 h for SARS-CoV-2 pneumonia were consecutively included between February and May 2020. VAP diagnosis required strict definition with clinical, radiological and quantitative microbiological confirmation. We assessed the association of VAP with corticosteroid treatment using univariate and multivariate cause-specific Cox's proportional hazard models with adjustment on pre-specified confounders. RESULTS: Among the 545 included patients, 191 (35%) received corticosteroids. The proportional hazard assumption for the effect of corticosteroids on the incidence of VAP could not be accepted, indicating that this effect varied during ICU stay. We found a non-significant lower risk of VAP for corticosteroid-treated patients during the first days in the ICU and an increased risk for longer ICU stay. By modeling the effect of corticosteroids with time-dependent coefficients, the association between corticosteroids and the incidence of VAP was not significant (overall effect p = 0.082), with time-dependent hazard ratios (95% confidence interval) of 0.47 (0.17-1.31) at day 2, 0.95 (0.63-1.42) at day 7, 1.48 (1.01-2.16) at day 14 and 1.94 (1.09-3.46) at day 21. CONCLUSIONS: No significant association was found between adjuvant corticosteroid treatment and the incidence of VAP, although a time-varying effect of corticosteroids was identified along the 28-day follow-up.publishersversionpublishe

a planned ancillary analysis of the coVAPid cohort

Funding: This study was supported in part by a grant from the French government through the «Programme Investissement d’Avenir» (I-SITE ULNE) managed by the Agence Nationale de la Recherche (coVAPid project). The funders of the study had no role in the study design, data collection, analysis, or interpreta tion, writing of the report, or decision to submit for publication.BACKGROUND: Patients with SARS-CoV-2 infection are at higher risk for ventilator-associated pneumonia (VAP). No study has evaluated the relationship between VAP and mortality in this population, or compared this relationship between SARS-CoV-2 patients and other populations. The main objective of our study was to determine the relationship between VAP and mortality in SARS-CoV-2 patients. METHODS: Planned ancillary analysis of a multicenter retrospective European cohort. VAP was diagnosed using clinical, radiological and quantitative microbiological criteria. Univariable and multivariable marginal Cox's regression models, with cause-specific hazard for duration of mechanical ventilation and ICU stay, were used to compare outcomes between study groups. Extubation, and ICU discharge alive were considered as events of interest, and mortality as competing event. FINDINGS: Of 1576 included patients, 568 were SARS-CoV-2 pneumonia, 482 influenza pneumonia, and 526 no evidence of viral infection at ICU admission. VAP was associated with significantly higher risk for 28-day mortality in SARS-CoV-2 (adjusted HR 1.70 (95% CI 1.16-2.47), p = 0.006), and influenza groups (1.75 (1.03-3.02), p = 0.045), but not in the no viral infection group (1.07 (0.64-1.78), p = 0.79). VAP was associated with significantly longer duration of mechanical ventilation in the SARS-CoV-2 group, but not in the influenza or no viral infection groups. VAP was associated with significantly longer duration of ICU stay in the 3 study groups. No significant difference was found in heterogeneity of outcomes related to VAP between the 3 groups, suggesting that the impact of VAP on mortality was not different between study groups. INTERPRETATION: VAP was associated with significantly increased 28-day mortality rate in SARS-CoV-2 patients. However, SARS-CoV-2 pneumonia, as compared to influenza pneumonia or no viral infection, did not significantly modify the relationship between VAP and 28-day mortality. CLINICAL TRIAL REGISTRATION: The study was registered at ClinicalTrials.gov, number NCT04359693.publishersversionpublishe

Modélisation thermo mécanique d un roulement à billes grande vitesse

La chaleur dégagée dans un palier à roulement fonctionnant à grande vitesse nécessite un refroidissement externe afin d éviter la dégradation du lubrifiant et du mécanisme. La technologie actuelle consiste ainsi à injecter dans celui-ci un jet d huile qui permet à la fois la lubrification des surfaces en contact mais également l évacuation de la chaleur. La compréhension des mécanismes de lubrification nécessite donc de mener des investigations conjointes sur les pertes de puissance au sein du roulement et sur les échauffements correspondants. La perte de puissance associée à la traînée aérodynamique exercée par le brouillard d huile sur les éléments roulants est extrêmement délicate à estimer du fait de la complexité des écoulements. Il existe ainsi un degré de liberté sur la manière d aborder cette perte, qui historiquement a toujours été ajustée de manière à égaliser les pertes de puissance globales calculée et mesurée. Ce phénomène a permis de masquer la divergence d opinions concernant la prise en compte ou non de la force de roulement hydrodynamique au contact bille/bague. Une méthode originale permettant de discriminer les différentes sources de chaleur est proposée, combinant les approches mécanique, thermique et aérodynamique. Il est ainsi démontré que les forces de roulement hydrodynamique et de traînée aérodynamique ne peuvent pas être négligées dans un roulement à billes grande vitesse. L outil numérique développé s avère performant et rapide pour modéliser le comportement thermo mécanique d un roulement en régime stationnaire et transitoire. Des investigations sur un scénario d interruption de la lubrification sont ainsi également réalisées. Ces aspects représentent une avancée technique dans la compréhension du rôle de l huile tant comme lubrifiant que comme fluide caloporteurHeat generation in high speed rolling element bearings needs external cooling in order to avoid the deterioration of the lubricant and the seizure of the mechanism. Current technology is to inject oil which lubricates contacting surfaces but also evacuates the generated heat. Then the understanding of lubrication mechanism deals with both power losses and thermal analyses. The power loss due to aerodynamic drag force acting on the rolling elements remains difficult to estimate due to the complex oil mist flow into the bearing. Historically it has been adjusted so that computed global power losses fit with experimental ones. It explains why nowadays there is still a discrepancy about taking into account or not hydrodynamic rolling traction forces at ball/race contacts. An original method is presented to discriminate the different heat sources by considering simultaneously mechanical, thermal and aerodynamical approaches. It is demonstrated that both aerodynamic drag forces and ball/race hydrodynamic rolling traction force cannot be neglected for high speed applications. The developed numerical tool appears to be fast and powerful to predict the steady state and unsteady state thermo mechanical behaviour of a rolling element bearing. Numerical investigations on oil shut-off are also presented. This work aims to provide a better comprehension of one of the most important aspects of tribology: the thermal effects in high speed rolling element bearings.VILLEURBANNE-DOC'INSA LYON (692662301) / SudocSudocFranceF

Power loss predictions in high-speed rolling element bearings using thermal networks

International audienceIn high-speed rolling element bearings (REB), the lubricant is used to separate the mating surfaces but also to cool down the parts while the system is in operation. In the context of optimizing oil circuits, a clear understanding of the lubricant cooling mechanisms is therefore required in order to reach a compromise between a good cooling capacity and the constraints on mass, size, and power. In this article, a model is presented that makes it possible to predict temperature distributions in high-speed thrust ball bearings. It is found that the prediction or measurement of global power loss cannot discriminate between several combinations of traction and drag forces. On the other hand, the predicted temperature distributions appear as very sensitive to the relative importance given to hydrodynamic rolling tractions or drag losses. Based on these findings, a methodology is suggested in order to define the most realistic power loss models to be used in high-speed REB simulations

Analyse thermique des paliers à roulements

Le niveau de température d'un roulement est fonction de nombreux paramètres comme la charge, la vitesse de rotation, le type et la viscosité du lubrifiant… Une approche de type réseau thermique a été développée pour évaluer les flux de chaleur et températures à l'intérieur d’un palier à roulements dit hautes vitesses. L'influence, sur le comportement thermique du palier, de la répartition des différents pertes de puissance à l'intérieur de celui-ci et du mélange air-huile est mis en évidence

Relationship between obesity and ventilator-associated pneumonia: a post-hoc analysis of the NUTRIREA2 trial.

International audiencePatients with obesity are at higher risk for community-acquired and nosocomial infections. However, no study has specifically evaluated the relationship between obesity and ventilator-associated pneumonia (VAP)

Le droit d’asile

Les Cahiers de la recherche sur les droits fondamentaux ont décidé de consacrer leur treizième numéro au droit d’asile, ce droit particulier qui doit tout à la fois protéger les droits de l’homme et respecter les prérogatives des États (François Julien-Laferrière). Au cœur des débats se situe la complexe question de la protection juridique à accorder au demandeur d’asile qui doit, pour accéder au statut de réfugié (en application de la Convention de Genève du 28 juillet 1951), « crain[dre] avec raison » d’être persécuté « du fait de sa race, de sa religion, de sa nationalité, de son appartenance à un certain groupe social ou de ses opinions politiques ». Au-delà de son dossier thématique, ce numéro des Cahiers est enrichi par les deux rubriques habituelles de la revue que sont les « Variétés » et les « Chroniques »