82 research outputs found

    Shortening identification times: comparative observational study of three early blood culture testing protocols

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    BackgroundWhile early appropriate antibiotic therapy is a proven means of limiting the progression of infections, especially bacteremia, empirical antibiotic therapy in sepsis is ineffective up to 30%. The aim of this study was to compare early blood culture testing protocols in terms of their ability to shorten the delay between blood sampling and appropriate antibiotic therapy.MethodsIn this french observational study, we compared three blood culture testing protocols. Positive blood cultures were tested using either GenMark ePlex panels (multiplex PCR period), a combination of MRSA/SA PCR, ÎČ-Lacta and oxidase tests (multitest period), or conventional identification and susceptibility tests only (reference period). Conventional identification and susceptibility tests were performed in parallel for all samples, as the gold standard.ResultsAmong the 270 patients with positive blood cultures included, early and conventional results were in good agreement, especially for the multitest period. The delay between a blood culture positivity and initial results was 3.8 (2.9–6.9) h in the multiplex PCR period, 2.6 (1.3–4.5) h in the multitest period and 3.7 (1.8–8.2) h in the reference period (p<0.01). Antibiotic therapy was initiated or adjusted in 68 patients based on early analysis results. The proportion of patients receiving appropriate antibiotic therapy within 48 h of blood sampling was higher in the multiplex PCR and multitest periods, (respectively 90% and 88%) than in the reference period (71%).ConclusionThese results suggest rapid bacterial identification and antibiotic resistance tests are feasible, efficient and can expedite appropriate antibiotic therapy

    Effect of Gas Atmosphere on Catalytic Behaviour of Zirconia, Ceria and Ceria Zirconia Catalysts in Valeric Acid Ketonization

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    [EN] Ketonization of valeric acid, which can be obtained by lignocellulosic biomass conversion, was carried out in a fixed bed flow reactor over ZrO2, 5-20 % CeO2/ZrO2 and CeO2 both under hydrogen and nitrogen stream at 628 K and atmospheric pressure. Regardless gas-carrier 10 wt% CeO2/ZrO2 was found to show higher catalytic activity compared to zirconia per se as well as other ceria modified zirconia while ceria per se exhibited very low catalytic activity. All catalysts provided higher acid conversion in H-2 than in N-2 whereas selectivity to 5-nonanone was insensitive to gas atmosphere. XRD, FTIR, UV-Vis DRS, XPS, HRTEM methods were applied to characterize catalysts in reduced and unreduced states simulating corresponding reaction conditions during acid ketonization. XRD did not reveal any changes in zirconia and ceria/zirconia lattice parameters as well as crystalline phase depending on gas atmosphere while insertion of ceria in zirconia caused notable increase in lattice parameter indicating some distortion of crystalline structure. According to XPS, FTIR and UV-Vis methods, the carrier gas was found to affect catalyst surface composition leading to alteration in Lewis acid sites ratio. Appearance of Zr3+ cations was observed on the ZrO2 surface after hydrogen pretreatment whereas only Zr4+ cations were determined using nitrogen as a gas-carrier. These changes of catalyst's surface cation composition affected corresponding activity in ketonization probably being crucial for reaction mechanism involving metal cations catalytic centers for acid adsorption and COO- stabilization at the initial step.Financial support from the Russian Foundation of Basic Research (RFBR Grant No 11-03-94001-CSIC) is gratefully acknowledged. This work was supported by the Federal Program "Scientific and Educational Cadres of Russia'' (Grant No 2012-1.5-12-000-1013-002). The authors also wish to thank Dr. Evgeniy Gerasimov, Dr. Igor Prosvirin, Dr. Demid Demidov from the Department of Physicochemical Methods at the Boreskov Institute of Catalysis for TEM and XPS measurements.Zaytseva, YA.; Panchenko, VN.; Simonov, MN.; Shutilov, AA.; Zenkovets, GA.; Renz, M.; Simakova, IL.... (2013). Effect of Gas Atmosphere on Catalytic Behaviour of Zirconia, Ceria and Ceria Zirconia Catalysts in Valeric Acid Ketonization. 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    Altimetry for the future: Building on 25 years of progress

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    In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

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

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    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/)

    The SIB Swiss Institute of Bioinformatics' resources: focus on curated databases

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    The SIB Swiss Institute of Bioinformatics (www.isb-sib.ch) provides world-class bioinformatics databases, software tools, services and training to the international life science community in academia and industry. These solutions allow life scientists to turn the exponentially growing amount of data into knowledge. Here, we provide an overview of SIB's resources and competence areas, with a strong focus on curated databases and SIB's most popular and widely used resources. In particular, SIB's Bioinformatics resource portal ExPASy features over 150 resources, including UniProtKB/Swiss-Prot, ENZYME, PROSITE, neXtProt, STRING, UniCarbKB, SugarBindDB, SwissRegulon, EPD, arrayMap, Bgee, SWISS-MODEL Repository, OMA, OrthoDB and other databases, which are briefly described in this article

    Altimetry for the future: building on 25 years of progress

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    In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

    Exploration de la fonction musculaire respiratoire et de l'amyotrophie des patients de soins intensifs : intĂ©rĂȘt des techniques Ă©chographiques

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    Patient diaphragms experience frequent and early aggression related to mechanical ventilation and sepsis in critical care. This aggression causes a diaphragmatic dysfunction which is often underestimated in the first days of ICU stay because it is clinically silent. It can however be a decisive prognostic factor associated with duration of weaning from mechanical ventilation, length of stay and mortality. Simple and robust methods are needed to better characterize some diaphragm properties in ICU: its trophicity, strength and coupling to mechanical ventilation. Ultrasound is a simple and accessible technique that allows superficial and deep observation of the diaphragm. Objectives Understand and clarify the physiological significance of the different ultrasound indices that can be used by the clinician to explore the diaphragm. Characterize the muscular atrophy associated with the first days of mechanical ventilation. Determine the relevance of diaphragm ultrasound in different clinical situations: support for the order-to-extubate decision and screening for patient-ventilator asynchronies. Populations and Methods Three descriptive prospective clinical studies (including one multicenter) and one study in healthy volunteers were used to support the thesis. Results Measurement of the thickening fraction of the diaphragm in zone of apposition appears to be correlated with work of breathing in patients under non-invasive ventilation, but the index is influenced by multiple factors and its precision weakened by a high variability. An atrophy of the diaphragm during the first five days of ventilation is noticeable by ultrasound in zone of apposition and does not seem to correlate with the atrophy of the pectoralis. Neither the excursion nor the thickening fraction measured after a successful spontaneous breathing test and before the extubation can help to predict its success. On the other hand, the combined analyze of diaphragmatic movements in time-motion mode and airway pressure curves makes it possible to diagnosis and characterize the main asynchronies in noninvasive ventilation in healthy volunteer. Conclusion Ultrasound enables the investigation of the diaphragm atrophy in ICU. The appreciation of the respiratory work of breathing by the thickening fraction of thickening must be tempered by the numerous limits of this index. The diaphragm ultrasound seems injudicious to guide the decision to extubate in ICU but could be relevant to detect and characterize the main patient-ventilator asynchronies under non-invasive ventilation.Le diaphragme des patients de soins critiques subit une agression frĂ©quente et prĂ©coce principalement en rapport avec la ventilation mĂ©canique et le sepsis. Cette agression entraine une dysfonction diaphragmatique souvent mĂ©connue dans les premiers jours de rĂ©animation car cliniquement silencieuse. Au moment de la levĂ©e de sĂ©dation, elle peut se rĂ©vĂ©ler un facteur pronostic dĂ©cisif sur la durĂ©e de sevrage ventilatoire, la durĂ©e de sĂ©jour et la survie. Des mĂ©thodes simples et robustes sont nĂ©cessaires pour mieux caractĂ©riser certaines propriĂ©tĂ©s du diaphragme des patients de rĂ©animation : sa trophicitĂ©, sa puissance et son couplage Ă  la ventilation mĂ©canique. L’échographie est une technique simple et accessible qui permet l’observation superficielle et en profondeur de ce muscle respiratoire. Objectifs Comprendre et prĂ©ciser la signification physiologique de diffĂ©rents indices Ă©chographiques utilisables par le clinicien pour aborder le diaphragme. CaractĂ©riser l’atrophie musculaire associĂ©e aux premiers jours de ventilation mĂ©canique. DĂ©terminer la pertinence de l’échographie du diaphragme dans diffĂ©rentes situations cliniques : aide Ă  la dĂ©cision d’extubation et dĂ©pistage des asynchronies patient-ventilateur. Populations et MĂ©thodes Trois Ă©tudes cliniques prospectives descriptives (dont une multicentrique) et une Ă©tude chez le volontaire sain ont servi de support Ă  la thĂšse. RĂ©sultats La fraction d’épaississement mesurĂ©e au niveau de la zone d’apposition du diaphragme semble corrĂ©lĂ©e au travail respiratoire chez des patients sous ventilation non invasive mais l’indice est influencĂ© par de multiples facteurs et sa prĂ©cision affaiblie par une variabilitĂ© Ă©levĂ©e. Une atrophie du diaphragme pendant les cinq premiers jours de ventilation est visualisable par Ă©chographie de la zone d’apposition et ne semble pas corrĂ©lĂ©e Ă  l’atrophie du pectoral. Ni l’excursion, ni l’épaississement mesurĂ©s aprĂšs rĂ©ussite d’une Ă©preuve de ventilation spontanĂ©e et avant extubation ne peuvent aider Ă  prĂ©dire l’issue de l’extubation. En revanche l’observation combinĂ©e des mouvements diaphragmatiques enregistrĂ©s en mode temps-mouvement couplĂ©s aux courbes de pression des voies aĂ©riennes permet le dĂ©pistage et la caractĂ©risation des principales asynchronies en ventilation non invasive chez le volontaire sain. Conclusion L’échographie permet d’investiguer l’atrophie du diaphragme en rĂ©animation. L’apprĂ©ciation du travail respiratoire par la fraction d’épaississement doit tenir compte des nombreuses limites de cet indice. L’échographie du diaphragme semble peu judicieuse pour orienter la dĂ©cision d’extubation en rĂ©animation mais pourrait ĂȘtre pertinente pour dĂ©pister et caractĂ©riser les principales asynchronies patient-ventilateur sous ventilation non-invasive

    Exploration de la fonction musculaire respiratoire et de l'amyotrophie des patients de soins intensifs : intĂ©rĂȘt des techniques Ă©chographiques

    No full text
    Patient diaphragms experience frequent and early aggression related to mechanical ventilation and sepsis in critical care. This aggression causes a diaphragmatic dysfunction which is often underestimated in the first days of ICU stay because it is clinically silent. It can however be a decisive prognostic factor associated with duration of weaning from mechanical ventilation, length of stay and mortality. Simple and robust methods are needed to better characterize some diaphragm properties in ICU: its trophicity, strength and coupling to mechanical ventilation. Ultrasound is a simple and accessible technique that allows superficial and deep observation of the diaphragm. Objectives Understand and clarify the physiological significance of the different ultrasound indices that can be used by the clinician to explore the diaphragm. Characterize the muscular atrophy associated with the first days of mechanical ventilation. Determine the relevance of diaphragm ultrasound in different clinical situations: support for the order-to-extubate decision and screening for patient-ventilator asynchronies. Populations and Methods Three descriptive prospective clinical studies (including one multicenter) and one study in healthy volunteers were used to support the thesis. Results Measurement of the thickening fraction of the diaphragm in zone of apposition appears to be correlated with work of breathing in patients under non-invasive ventilation, but the index is influenced by multiple factors and its precision weakened by a high variability. An atrophy of the diaphragm during the first five days of ventilation is noticeable by ultrasound in zone of apposition and does not seem to correlate with the atrophy of the pectoralis. Neither the excursion nor the thickening fraction measured after a successful spontaneous breathing test and before the extubation can help to predict its success. On the other hand, the combined analyze of diaphragmatic movements in time-motion mode and airway pressure curves makes it possible to diagnosis and characterize the main asynchronies in noninvasive ventilation in healthy volunteer. Conclusion Ultrasound enables the investigation of the diaphragm atrophy in ICU. The appreciation of the respiratory work of breathing by the thickening fraction of thickening must be tempered by the numerous limits of this index. The diaphragm ultrasound seems injudicious to guide the decision to extubate in ICU but could be relevant to detect and characterize the main patient-ventilator asynchronies under non-invasive ventilation.Le diaphragme des patients de soins critiques subit une agression frĂ©quente et prĂ©coce principalement en rapport avec la ventilation mĂ©canique et le sepsis. Cette agression entraine une dysfonction diaphragmatique souvent mĂ©connue dans les premiers jours de rĂ©animation car cliniquement silencieuse. Au moment de la levĂ©e de sĂ©dation, elle peut se rĂ©vĂ©ler un facteur pronostic dĂ©cisif sur la durĂ©e de sevrage ventilatoire, la durĂ©e de sĂ©jour et la survie. Des mĂ©thodes simples et robustes sont nĂ©cessaires pour mieux caractĂ©riser certaines propriĂ©tĂ©s du diaphragme des patients de rĂ©animation : sa trophicitĂ©, sa puissance et son couplage Ă  la ventilation mĂ©canique. L’échographie est une technique simple et accessible qui permet l’observation superficielle et en profondeur de ce muscle respiratoire. Objectifs Comprendre et prĂ©ciser la signification physiologique de diffĂ©rents indices Ă©chographiques utilisables par le clinicien pour aborder le diaphragme. CaractĂ©riser l’atrophie musculaire associĂ©e aux premiers jours de ventilation mĂ©canique. DĂ©terminer la pertinence de l’échographie du diaphragme dans diffĂ©rentes situations cliniques : aide Ă  la dĂ©cision d’extubation et dĂ©pistage des asynchronies patient-ventilateur. Populations et MĂ©thodes Trois Ă©tudes cliniques prospectives descriptives (dont une multicentrique) et une Ă©tude chez le volontaire sain ont servi de support Ă  la thĂšse. RĂ©sultats La fraction d’épaississement mesurĂ©e au niveau de la zone d’apposition du diaphragme semble corrĂ©lĂ©e au travail respiratoire chez des patients sous ventilation non invasive mais l’indice est influencĂ© par de multiples facteurs et sa prĂ©cision affaiblie par une variabilitĂ© Ă©levĂ©e. Une atrophie du diaphragme pendant les cinq premiers jours de ventilation est visualisable par Ă©chographie de la zone d’apposition et ne semble pas corrĂ©lĂ©e Ă  l’atrophie du pectoral. Ni l’excursion, ni l’épaississement mesurĂ©s aprĂšs rĂ©ussite d’une Ă©preuve de ventilation spontanĂ©e et avant extubation ne peuvent aider Ă  prĂ©dire l’issue de l’extubation. En revanche l’observation combinĂ©e des mouvements diaphragmatiques enregistrĂ©s en mode temps-mouvement couplĂ©s aux courbes de pression des voies aĂ©riennes permet le dĂ©pistage et la caractĂ©risation des principales asynchronies en ventilation non invasive chez le volontaire sain. Conclusion L’échographie permet d’investiguer l’atrophie du diaphragme en rĂ©animation. L’apprĂ©ciation du travail respiratoire par la fraction d’épaississement doit tenir compte des nombreuses limites de cet indice. L’échographie du diaphragme semble peu judicieuse pour orienter la dĂ©cision d’extubation en rĂ©animation mais pourrait ĂȘtre pertinente pour dĂ©pister et caractĂ©riser les principales asynchronies patient-ventilateur sous ventilation non-invasive

    Exploration de la fonction musculaire respiratoire et de l'amyotrophie des patients de soins intensifs : intĂ©rĂȘt des techniques Ă©chographiques

    No full text
    Patient diaphragms experience frequent and early aggression related to mechanical ventilation and sepsis in critical care. This aggression causes a diaphragmatic dysfunction which is often underestimated in the first days of ICU stay because it is clinically silent. It can however be a decisive prognostic factor associated with duration of weaning from mechanical ventilation, length of stay and mortality. Simple and robust methods are needed to better characterize some diaphragm properties in ICU: its trophicity, strength and coupling to mechanical ventilation. Ultrasound is a simple and accessible technique that allows superficial and deep observation of the diaphragm. Objectives Understand and clarify the physiological significance of the different ultrasound indices that can be used by the clinician to explore the diaphragm. Characterize the muscular atrophy associated with the first days of mechanical ventilation. Determine the relevance of diaphragm ultrasound in different clinical situations: support for the order-to-extubate decision and screening for patient-ventilator asynchronies. Populations and Methods Three descriptive prospective clinical studies (including one multicenter) and one study in healthy volunteers were used to support the thesis. Results Measurement of the thickening fraction of the diaphragm in zone of apposition appears to be correlated with work of breathing in patients under non-invasive ventilation, but the index is influenced by multiple factors and its precision weakened by a high variability. An atrophy of the diaphragm during the first five days of ventilation is noticeable by ultrasound in zone of apposition and does not seem to correlate with the atrophy of the pectoralis. Neither the excursion nor the thickening fraction measured after a successful spontaneous breathing test and before the extubation can help to predict its success. On the other hand, the combined analyze of diaphragmatic movements in time-motion mode and airway pressure curves makes it possible to diagnosis and characterize the main asynchronies in noninvasive ventilation in healthy volunteer. Conclusion Ultrasound enables the investigation of the diaphragm atrophy in ICU. The appreciation of the respiratory work of breathing by the thickening fraction of thickening must be tempered by the numerous limits of this index. The diaphragm ultrasound seems injudicious to guide the decision to extubate in ICU but could be relevant to detect and characterize the main patient-ventilator asynchronies under non-invasive ventilation.Le diaphragme des patients de soins critiques subit une agression frĂ©quente et prĂ©coce principalement en rapport avec la ventilation mĂ©canique et le sepsis. Cette agression entraine une dysfonction diaphragmatique souvent mĂ©connue dans les premiers jours de rĂ©animation car cliniquement silencieuse. Au moment de la levĂ©e de sĂ©dation, elle peut se rĂ©vĂ©ler un facteur pronostic dĂ©cisif sur la durĂ©e de sevrage ventilatoire, la durĂ©e de sĂ©jour et la survie. Des mĂ©thodes simples et robustes sont nĂ©cessaires pour mieux caractĂ©riser certaines propriĂ©tĂ©s du diaphragme des patients de rĂ©animation : sa trophicitĂ©, sa puissance et son couplage Ă  la ventilation mĂ©canique. L’échographie est une technique simple et accessible qui permet l’observation superficielle et en profondeur de ce muscle respiratoire. Objectifs Comprendre et prĂ©ciser la signification physiologique de diffĂ©rents indices Ă©chographiques utilisables par le clinicien pour aborder le diaphragme. CaractĂ©riser l’atrophie musculaire associĂ©e aux premiers jours de ventilation mĂ©canique. DĂ©terminer la pertinence de l’échographie du diaphragme dans diffĂ©rentes situations cliniques : aide Ă  la dĂ©cision d’extubation et dĂ©pistage des asynchronies patient-ventilateur. Populations et MĂ©thodes Trois Ă©tudes cliniques prospectives descriptives (dont une multicentrique) et une Ă©tude chez le volontaire sain ont servi de support Ă  la thĂšse. RĂ©sultats La fraction d’épaississement mesurĂ©e au niveau de la zone d’apposition du diaphragme semble corrĂ©lĂ©e au travail respiratoire chez des patients sous ventilation non invasive mais l’indice est influencĂ© par de multiples facteurs et sa prĂ©cision affaiblie par une variabilitĂ© Ă©levĂ©e. Une atrophie du diaphragme pendant les cinq premiers jours de ventilation est visualisable par Ă©chographie de la zone d’apposition et ne semble pas corrĂ©lĂ©e Ă  l’atrophie du pectoral. Ni l’excursion, ni l’épaississement mesurĂ©s aprĂšs rĂ©ussite d’une Ă©preuve de ventilation spontanĂ©e et avant extubation ne peuvent aider Ă  prĂ©dire l’issue de l’extubation. En revanche l’observation combinĂ©e des mouvements diaphragmatiques enregistrĂ©s en mode temps-mouvement couplĂ©s aux courbes de pression des voies aĂ©riennes permet le dĂ©pistage et la caractĂ©risation des principales asynchronies en ventilation non invasive chez le volontaire sain. Conclusion L’échographie permet d’investiguer l’atrophie du diaphragme en rĂ©animation. L’apprĂ©ciation du travail respiratoire par la fraction d’épaississement doit tenir compte des nombreuses limites de cet indice. L’échographie du diaphragme semble peu judicieuse pour orienter la dĂ©cision d’extubation en rĂ©animation mais pourrait ĂȘtre pertinente pour dĂ©pister et caractĂ©riser les principales asynchronies patient-ventilateur sous ventilation non-invasive

    Exploration of respiratory muscle function and amyotrophy in intensive care patients : interest of ultrasound techniques

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    Le diaphragme des patients de soins critiques subit une agression frĂ©quente et prĂ©coce principalement en rapport avec la ventilation mĂ©canique et le sepsis. Cette agression entraine une dysfonction diaphragmatique souvent mĂ©connue dans les premiers jours de rĂ©animation car cliniquement silencieuse. Au moment de la levĂ©e de sĂ©dation, elle peut se rĂ©vĂ©ler un facteur pronostic dĂ©cisif sur la durĂ©e de sevrage ventilatoire, la durĂ©e de sĂ©jour et la survie. Des mĂ©thodes simples et robustes sont nĂ©cessaires pour mieux caractĂ©riser certaines propriĂ©tĂ©s du diaphragme des patients de rĂ©animation : sa trophicitĂ©, sa puissance et son couplage Ă  la ventilation mĂ©canique. L’échographie est une technique simple et accessible qui permet l’observation superficielle et en profondeur de ce muscle respiratoire. Objectifs Comprendre et prĂ©ciser la signification physiologique de diffĂ©rents indices Ă©chographiques utilisables par le clinicien pour aborder le diaphragme. CaractĂ©riser l’atrophie musculaire associĂ©e aux premiers jours de ventilation mĂ©canique. DĂ©terminer la pertinence de l’échographie du diaphragme dans diffĂ©rentes situations cliniques : aide Ă  la dĂ©cision d’extubation et dĂ©pistage des asynchronies patient-ventilateur. Populations et MĂ©thodes Trois Ă©tudes cliniques prospectives descriptives (dont une multicentrique) et une Ă©tude chez le volontaire sain ont servi de support Ă  la thĂšse. RĂ©sultats La fraction d’épaississement mesurĂ©e au niveau de la zone d’apposition du diaphragme semble corrĂ©lĂ©e au travail respiratoire chez des patients sous ventilation non invasive mais l’indice est influencĂ© par de multiples facteurs et sa prĂ©cision affaiblie par une variabilitĂ© Ă©levĂ©e. Une atrophie du diaphragme pendant les cinq premiers jours de ventilation est visualisable par Ă©chographie de la zone d’apposition et ne semble pas corrĂ©lĂ©e Ă  l’atrophie du pectoral. Ni l’excursion, ni l’épaississement mesurĂ©s aprĂšs rĂ©ussite d’une Ă©preuve de ventilation spontanĂ©e et avant extubation ne peuvent aider Ă  prĂ©dire l’issue de l’extubation. En revanche l’observation combinĂ©e des mouvements diaphragmatiques enregistrĂ©s en mode temps-mouvement couplĂ©s aux courbes de pression des voies aĂ©riennes permet le dĂ©pistage et la caractĂ©risation des principales asynchronies en ventilation non invasive chez le volontaire sain. Conclusion L’échographie permet d’investiguer l’atrophie du diaphragme en rĂ©animation. L’apprĂ©ciation du travail respiratoire par la fraction d’épaississement doit tenir compte des nombreuses limites de cet indice. L’échographie du diaphragme semble peu judicieuse pour orienter la dĂ©cision d’extubation en rĂ©animation mais pourrait ĂȘtre pertinente pour dĂ©pister et caractĂ©riser les principales asynchronies patient-ventilateur sous ventilation non-invasive.Patient diaphragms experience frequent and early aggression related to mechanical ventilation and sepsis in critical care. This aggression causes a diaphragmatic dysfunction which is often underestimated in the first days of ICU stay because it is clinically silent. It can however be a decisive prognostic factor associated with duration of weaning from mechanical ventilation, length of stay and mortality. Simple and robust methods are needed to better characterize some diaphragm properties in ICU: its trophicity, strength and coupling to mechanical ventilation. Ultrasound is a simple and accessible technique that allows superficial and deep observation of the diaphragm. Objectives Understand and clarify the physiological significance of the different ultrasound indices that can be used by the clinician to explore the diaphragm. Characterize the muscular atrophy associated with the first days of mechanical ventilation. Determine the relevance of diaphragm ultrasound in different clinical situations: support for the order-to-extubate decision and screening for patient-ventilator asynchronies. Populations and Methods Three descriptive prospective clinical studies (including one multicenter) and one study in healthy volunteers were used to support the thesis. Results Measurement of the thickening fraction of the diaphragm in zone of apposition appears to be correlated with work of breathing in patients under non-invasive ventilation, but the index is influenced by multiple factors and its precision weakened by a high variability. An atrophy of the diaphragm during the first five days of ventilation is noticeable by ultrasound in zone of apposition and does not seem to correlate with the atrophy of the pectoralis. Neither the excursion nor the thickening fraction measured after a successful spontaneous breathing test and before the extubation can help to predict its success. On the other hand, the combined analyze of diaphragmatic movements in time-motion mode and airway pressure curves makes it possible to diagnosis and characterize the main asynchronies in noninvasive ventilation in healthy volunteer. Conclusion Ultrasound enables the investigation of the diaphragm atrophy in ICU. The appreciation of the respiratory work of breathing by the thickening fraction of thickening must be tempered by the numerous limits of this index. The diaphragm ultrasound seems injudicious to guide the decision to extubate in ICU but could be relevant to detect and characterize the main patient-ventilator asynchronies under non-invasive ventilation
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