Origin of the ionized wind in MWC 349A

The UC-HII region of MWC 349A is the prototype of an ionized wind driven by a massive star surrounded by a disk. Recent high angular resolution observations of the millimeter recombination lines have shown that the disk rotates with a Keplerian law in its outer parts. However, the kinematics of innermost regions in the UC-HII region of MWC 349A is still unknown, in particular the radius where the wind is launched from the disk. We performed hydrogen recombination line observations with the Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory to study the kinematics of its innermost regions by studying their spectral features. In addition to the two laser peaks, we report the first detection of two new components that are blueshifted with respect to the laser peaks for all the recombination lines with principal quantum number n<22. These new spectral features originate from the region where the wind is ejected from the disk. We used our 3D non-LTE radiative transfer model for recombination lines (MORELI) to show that these features are consistent with the wind being ejected at a radius of about 24 AU from the star, which supports magnetohydrodynamic wind models.Comment: 5 pages, 5 figure

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Clustering COVID-19 ARDS patients through the first days of ICU admission. An analysis of the CIBERESUCICOVID Cohort

Background Acute respiratory distress syndrome (ARDS) can be classified into sub-phenotypes according to different inflammatory/clinical status. Prognostic enrichment was achieved by grouping patients into hypoinflammatory or hyperinflammatory sub-phenotypes, even though the time of analysis may change the classification according to treatment response or disease evolution. We aimed to evaluate when patients can be clustered in more than 1 group, and how they may change the clustering of patients using data of baseline or day 3, and the prognosis of patients according to their evolution by changing or not the cluster.Methods Multicenter, observational prospective, and retrospective study of patients admitted due to ARDS related to COVID-19 infection in Spain. Patients were grouped according to a clustering mixed-type data algorithm (k-prototypes) using continuous and categorical readily available variables at baseline and day 3.Results Of 6205 patients, 3743 (60%) were included in the study. According to silhouette analysis, patients were grouped in two clusters. At baseline, 1402 (37%) patients were included in cluster 1 and 2341(63%) in cluster 2. On day 3, 1557(42%) patients were included in cluster 1 and 2086 (57%) in cluster 2. The patients included in cluster 2 were older and more frequently hypertensive and had a higher prevalence of shock, organ dysfunction, inflammatory biomarkers, and worst respiratory indexes at both time points. The 90-day mortality was higher in cluster 2 at both clustering processes (43.8% [n = 1025] versus 27.3% [n = 383] at baseline, and 49% [n = 1023] versus 20.6% [n = 321] on day 3). Four hundred and fifty-eight (33%) patients clustered in the first group were clustered in the second group on day 3. In contrast, 638 (27%) patients clustered in the second group were clustered in the first group on day 3.Conclusions During the first days, patients can be clustered into two groups and the process of clustering patients may change as they continue to evolve. This means that despite a vast majority of patients remaining in the same cluster, a minority reaching 33% of patients analyzed may be re-categorized into different clusters based on their progress. Such changes can significantly impact their prognosis

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

[Montreal 1976] [Material gráfico]

Contiene fotografías pertenecientes al archivo fotográfico del diario "Región", publicadas entre 1974 y 1976, aunque la mayoría en 1976Todas las fotografías firmadas por Foto E. Gar (Oviedo), Cifra Gráfica, y EF

Caracterización de la cinemática de los vientos y los discos circunestelares ionizados de regiones UC HII con emisión máser en líneas de recombinación de hidrógeno

Aunque las estrellas masivas han jugado un papel clave en la evolución de las galaxias, todavía no hay un consenso acerca de cómo se forman y de cuáles son los procesos físicos que afectan a su evolución temprana. Con el objetivo de avanzar en el conocimiento de estos procesos, hemos estudiado la cinemática de las regiones ultracompactas ionizadas (UC HII) analizando la emisión de líneas de recombinación (LR) de hidrógeno a longitudes de onda de radio y submm, especialmente de aquellas fuentes en las que este tipo de emisión es de tipo máser. Esto ha estado motivado por poderse utilizar las fuertes intensidades de estas líneas para llevar a cabo estudios con una alta resolución espectral y espacial. Para ello, se ha desarrollado un código de transporte radiativo que simula la emisión de radiocontinuo y de LR, tanto en condiciones de equilibrio termodinámico local (ETL) o de no ETL, de regiones ionizadas. Este código, denominado MORELI, se ha utilizado sistemáticamente para caracterizar distintas regiones UC HII, modelando su emisiones utilizando distintas geometrías, y estructuras de densidad electrónica, temperatura y cinemática. ResultadosEn primer lugar, el código MORELI se ha utilizado para llevar a cabo un completo modelado de todos los datos observacionales que se dispone de la emisión de radiocontinuo y de LR de la única fuente que se conocía con emisión máser en LR: la región UC HII existente en torno a la estrella masiva de MWC349A. Hemos mostrado que los perfiles y distribución espacial de la emisión de LR máser son bastante dependientes de su cinemática y estructura física. Por ello, su modelado y comparación con las observaciones nos ha permitido aportar fuertes restricciones acerca de sus características. Los principales resultados han sido los siguientes: a) Las LR máser se originan en un disco circunestelar ionizado que está rotando keplerianamente en torno a una estrella con 38 masas solares. b) El viento ionizado se origina por lanzamiento de gas ionizado desde el disco. c) El radio de lanzamiento del viento ionizado ocurre a una distancia de unas 24 ua de la estrella central, lo que apoya la idea de que los modelos magnetohidrodinámicos y, en concreto, los modelos de vientos de disco, son los que permiten explicar la formación de su viento.Por otra parte, la utilización de las nuevas capacidades de los instrumentos mm y submm nos ha permitido detectar emisión máser en LR hacia nuevas regiones UC HII. En concreto, el incremento del ancho de banda disponible para las observaciones espectroscópicas permitió detectar por primera vez LR con anchuras de unos 500 km/s hacia Cepheus A HW2. Por otra parte, la detección de LR hacia Monoceros R2-IRS2, con perfiles de doble pico, ha mostrado la necesidad de realizar observaciones con una alta resolución espacial, utilizando interferómetros, para filtrar la emisión ópticamente delgada de la región extensa y, así, detectar la emisión máser procedente de las regiones más densas e internas. Además, el modelado realizado con MORELI de estas dos regiones, nos ha permitido caracterizar sus geometrías, distribuciones de densidad electrónica y cinemática. Asimismo, hemos identificado en la literatura otra fuente, la región UC HII de G35.58-0.03, cuya emisión de LR también parece ser debida a emisión máser.ConclusionesEn definitiva, se ha presentado uno de los estudios más detallados realizados acerca de un disco circunestelar en torno a una estrella masiva en formación, concluyéndose que el campo magnético juega un papel clave en la evolución del disco de MWC349A. Por otra parte, la detección de nuevas regiones UC HII con LR máser ha mostrado que este tipo de emisión es más común de lo que podría haberse pensado. Todos estos resultados indican que estas líneas pueden proporcionar, a corto plazo, importantes avances en el conocimiento de los procesos que afectan a estas regiones

Imaging the Jet of MWC 349A with Resolved Radio Recombination Line Emission from ALMA

Jets and disk winds arise from materials with excess angular momentum ejected from the accretion disks in forming stars. How these structures are launched and how they impact the gas within the innermost regions of these objects remains poorly understood. MWC349A is a massive star that has a circumstellar disk that rotates in accord with Kepler’s Law, with an ionized wind and a high-velocity jet launched from the disk surface. The strongly maser-amplified emission of hydrogen radio recombination lines (RRLs) observed toward this system provides a comprehensive picture of its ionized environment with exquisite detail. In this Letter, we present Atacama Large Millimeter/submillimeter Array observations of the H26 α RRL and continuum emission obtained with the highest angular resolution ever used toward this source (beam of ∼0.″02). The maser RRL emission is resolved for the first time and clearly delineates the ionized disk, wind, and jet. We analyzed the RRL data cubes with the 3D non-LTE radiative transfer model MORELI, confirming that the jet is poorly collimated. We found that the jet orientation is closer to the rotation axis of the system than derived from spatially unresolved data. This study confirms that hydrogen RRL masers are powerful probes of the physical structure and kinematics of the innermost ionized material around massive stars