Estudio de sensibilidad de parámetros de modelos en flujos cavitantes en régimen no estacionario

La cavitación es un complejo fenómeno físico que se presenta generalmente en flujos turbulentos afectado por varios factores, como la presión del sistema y la concentración de gases no condensables disueltos. Para analizar este comportamiento se han desarrollado modelos matemáticos, algunos de los cuales se encuentran dentro de software de simulaciones comerciales. Para ser aplicados, junto con modelos de turbulencia, deben fijarse cierto número de parámetros de calibración que han sido establecidos sólo para un número reducido de tipos de flujo (geometrías simples, variables del fluido típicas, flujo no desprendido, etc.). Cuando empieza a aparecer el flujo reverso, incluso en geometrías simples, la capacidad de predecir correctamente el fenómeno de cavitación es menor y se cree que un estudio cuidadoso de sensibilidad de parámetros es útil a la hora de realizar aplicaciones de simulación a casos industriales. Este trabajo amplía resultados ya obtenidos anteriormente, estudiando en detalle los modelos de mejor comportamiento ya seleccionados, producto de la experiencia adquirida. Se busca ahora identificar la mejor combinación de parámetros a través de la comparación de resultados experimentales de flujos cavitantes, de características fuertemente no estacionarias, de típica aparición en turbomáquinas hidráulicas (TMH), extendiendo los trabajos de calibración ya realizados anteriormente. Se ha seguido utilizando geometrías simples (tipo Venturi) con el objeto de centrarse en los modelos de turbulencia y cavitación ya probados para casos estacionarios y por tener una abundante información experimental de flujos cavitantes en estas geometrías. Los trabajos de validación/calibración se llevaron a cabo comparando perfiles de velocidad del fluido, la presión en la zona cavitante y la frecuencia del ciclo de crecimiento y decrecimiento de la cavidad, entre otras variables, ajustando los coeficientes de producción/disipación de energía turbulenta y algunos parámetros típicos del modelo de flujo cavitante los que pueden influir en la exactitud y estabilidad de las predicciones numéricas.Postprint (published version

Frequency of IgA antibodies in pemphigus, bullous pemphigoid and mucous membrane pemphigoid

Circulating and bound IgA antibodies can be found in the autoimmune blistering diseases, but their prevalence, clinical relevance and target antigens remain unknown. Thirty-two patients with pemphigus, 73 with bullous pemphigoid and 28 with mucous membrane pemphigoid were studied retrospectively. Direct immunofluorescence (DIF) analysis of IgG, IgA, IgM and C3 was carried out for all cases. Sera were studied by standard indirect immunofluorescence, indirect immunofluorescence on salt-split skin, immunoblotting for bullous pemphigoid and mucous membrane pemphigoid and ELISA for pemphigus. With DIF, we found IgA autoantibodies in 22 of all 133 cases. Circulating IgA antibodies to skin were detected in 2 of 3 IgA-DIF-positive patients with pemphigus, in 3 of 6 with bullous pemphigoid, and in 6 of 13 with mucous membrane pemphigoid. We confirm that the IgA reactivity is more frequently associated with mucous membrane involvement, especially in cases without critical involvement (5/8). The role of IgA and its antigenic specificity in these diseases remain unclear

Clinical value of left atrial appendage flow for prediction of long-term sinus rhythm maintenance in patients with nonvalvular atrial fibrillation

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Optimización de un banco de ensayos de cavitación mediante fluidodinámica computacional

Los flujos cavitantes se corresponden a una estructura bifásica (líquido-vapor) cuando la presión del líquido disminuye hasta su presión de vapor, pv. La aparición y el posterior colapso de cavidades de vapor cerca de paredes sólidas, generan pulsos de presión de alta frecuencia que ocasionan la falla por fatiga del material sólido, y pérdida de rendimiento y daño mecánico en turbomáquinas. Experimentos que identifican el patrón de flujos cavitantes muestran que el estado de cavitación desarrollada puede tener diferentes estructuras no estacionarias, en algunos casos del tipo periódica. Éstas dependen de su estado fluidodinámico, siendo algunas de ellas más agresivas desde el punto de vista del daño por cavitación. Relacionados con el daño por cavitación en materiales, existen montajes experimentales orientados a estudios que implican la búsqueda y/o desarrollo de materiales resistentes al daño por cavitación. Debido al alto costo de los experimentos en bancos hidrodinámicos, es de interés evaluar las condiciones óptimas de cavitación que maximicen el daño en probetas de materiales resistentes a este fenómeno. Esto puede hacerse mediante modelado numérico (CFD), ya que es posible caracterizar el tipo de estructura que posee la zona de vaporización/colapso de las burbujas en estos dispositivos de ensayo, aunque este tipo de flujo muestra una gran complejidad en su modelado, debido a que se debe tener en cuenta el estado bifásico y turbulento del flujo. El objetivo de este trabajo ha sido contribuir mediante el uso de CFD a la optimización del diseño de un banco de ensayos hidrodinámico actualmente en construcción, para el ensayo de probetas de diversos aleaciones de materiales que se usarán para recargue de álabes de turbinas. Se necesita garantizar que existan mecanismos de cavitación lo más agresivos posibles en el dispositivo de ensayo en donde se insertarán las probetas de cara a minimizar los tiempos de ensayo, que son del orden de 150 horas. El estudio mediante CFD se ha hecho aplicando diferentes modelos para la cavitación y para la turbulencia, utilizando los estudios de validación y de sensibilidad a parámetros de los submodelos ya realizados en un trabajo previo al presente trabajo.Postprint (published version

Head to head comparison of 2D vs real time 3D dipyridamole stress echocardiography

Real-time three-dimensional (RT-3D) echocardiography has entered the clinical practice but true incremental value over standard two-dimensional echocardiography (2D) remains uncertain when applied to stress echo. The aim of the present study is to establish the additional value of RT-3D stress echo over standard 2D stress echocardiography. We evaluated 23 consecutive patients (age = 65 ± 10 years, 16 men) referred for dipyridamole stress echocardiography with Sonos 7500 (Philips Medical Systems, Palo, Alto, CA) equipped with a phased – array 1.6–2.5 MHz probe with second harmonic capability for 2D imaging and a 2–4 MHz matrix-phased array transducer producing 60 × 70 volumetric pyramidal data containing the entire left ventricle for RT-3D imaging. In all patients, images were digitally stored in 2D and 3D for baseline and peak stress with a delay between acquisitions of less than 60 seconds. Wall motion analysis was interpreted on-line for 2D and off-line for RT-3D by joint reading of two expert stress ecocardiographist. Segmental image quality was scored from 1 = excellent to 5 = uninterpretable. Interpretable images were obtained in all patients. Acquisition time for 2D images was 67 ± 21 sec vs 40 ± 22 sec for RT-3D (p = 0.5). Wall motion analysis time was 2.8 ± 0.5 min for 2D and 13 ± 7 min for 3D (p = 0.0001). Segmental image quality score was 1.4 ± 0.5 for 2D and 2.6 ± 0.7 for 3D (p = 0.0001). Positive test results was found in 5/23 patients. 2D and RT-3D were in agreement in 3 out of these 5 positive exams. Overall stress result (positive vs negative) concordance was 91% (Kappa = 0.80) between 2D and RT-3D. During dipyridamole stress echocardiography RT-3D imaging is highly feasible and shows a high concordance rate with standard 2D stress echo. 2D images take longer time to acquire and RT-3D is more time-consuming to analyze. At present, there is no clear clinical advantage justifying routine RT-3D stress echocardiography use

TCT-637 Transcatheter Aortic Valve Implantation in Patients with Small Aortic Annuli Using the Edwards SAPIEN XT 20mm Balloon-Expanding Heart Valve: Early Clinical Results from A Multi-Center Registry

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Beta-Blocker Use in Older Hospitalized Patients Affected by Heart Failure and Chronic Obstructive Pulmonary Disease: An Italian Survey From the REPOSI Register

Beta (β)-blockers (BB) are useful in reducing morbidity and mortality in patients with heart failure (HF) and concomitant chronic obstructive pulmonary disease (COPD). Nevertheless, the use of BBs could induce bronchoconstriction due to β2-blockade. For this reason, both the ESC and GOLD guidelines strongly suggest the use of selective β1-BB in patients with HF and COPD. However, low adherence to guidelines was observed in multiple clinical settings. The aim of the study was to investigate the BBs use in older patients affected by HF and COPD, recorded in the REPOSI register. Of 942 patients affected by HF, 47.1% were treated with BBs. The use of BBs was significantly lower in patients with HF and COPD than in patients affected by HF alone, both at admission and at discharge (admission, 36.9% vs. 51.3%; discharge, 38.0% vs. 51.7%). In addition, no further BB users were found at discharge. The probability to being treated with a BB was significantly lower in patients with HF also affected by COPD (adj. OR, 95% CI: 0.50, 0.37-0.67), while the diagnosis of COPD was not associated with the choice of selective β1-BB (adj. OR, 95% CI: 1.33, 0.76-2.34). Despite clear recommendations by clinical guidelines, a significant underuse of BBs was also observed after hospital discharge. In COPD affected patients, physicians unreasonably reject BBs use, rather than choosing a β1-BB. The expected improvement of the BB prescriptions after hospitalization was not observed. A multidisciplinary approach among hospital physicians, general practitioners, and pharmacologists should be carried out for better drug management and adherence to guideline recommendations

Prescription appropriateness of anti-diabetes drugs in elderly patients hospitalized in a clinical setting: evidence from the REPOSI Register

Diabetes is an increasing global health burden with the highest prevalence (24.0%) observed in elderly people. Older diabetic adults have a greater risk of hospitalization and several geriatric syndromes than older nondiabetic adults. For these conditions, special care is required in prescribing therapies including anti- diabetes drugs. Aim of this study was to evaluate the appropriateness and the adherence to safety recommendations in the prescriptions of glucose-lowering drugs in hospitalized elderly patients with diabetes. Data for this cross-sectional study were obtained from the REgistro POliterapie-Società Italiana Medicina Interna (REPOSI) that collected clinical information on patients aged ≥ 65 years acutely admitted to Italian internal medicine and geriatric non-intensive care units (ICU) from 2010 up to 2019. Prescription appropriateness was assessed according to the 2019 AGS Beers Criteria and anti-diabetes drug data sheets.Among 5349 patients, 1624 (30.3%) had diagnosis of type 2 diabetes. At admission, 37.7% of diabetic patients received treatment with metformin, 37.3% insulin therapy, 16.4% sulfonylureas, and 11.4% glinides. Surprisingly, only 3.1% of diabetic patients were treated with new classes of anti- diabetes drugs. According to prescription criteria, at admission 15.4% of patients treated with metformin and 2.6% with sulfonylureas received inappropriately these treatments. At discharge, the inappropriateness of metformin therapy decreased (10.2%, P < 0.0001). According to Beers criteria, the inappropriate prescriptions of sulfonylureas raised to 29% both at admission and at discharge. This study shows a poor adherence to current guidelines on diabetes management in hospitalized elderly people with a high prevalence of inappropriate use of sulfonylureas according to the Beers criteria

The “Diabetes Comorbidome”: A Different Way for Health Professionals to Approach the Comorbidity Burden of Diabetes

(1) Background: The disease burden related to diabetes is increasing greatly, particularly in older subjects. A more comprehensive approach towards the assessment and management of diabetes’ comorbidities is necessary. The aim of this study was to implement our previous data identifying and representing the prevalence of the comorbidities, their association with mortality, and the strength of their relationship in hospitalized elderly patients with diabetes, developing, at the same time, a new graphic representation model of the comorbidome called “Diabetes Comorbidome”. (2) Methods: Data were collected from the RePoSi register. Comorbidities, socio-demographic data, severity and comorbidity indexes (Cumulative Illness rating Scale CIRS-SI and CIRS-CI), and functional status (Barthel Index), were recorded. Mortality rates were assessed in hospital and 3 and 12 months after discharge. (3) Results: Of the 4714 hospitalized elderly patients, 1378 had diabetes. The comorbidities distribution showed that arterial hypertension (57.1%), ischemic heart disease (31.4%), chronic renal failure (28.8%), atrial fibrillation (25.6%), and COPD (22.7%), were the more frequent in subjects with diabetes. The graphic comorbidome showed that the strongest predictors of death at in hospital and at the 3-month follow-up were dementia and cancer. At the 1-year follow-up, cancer was the first comorbidity independently associated with mortality. (4) Conclusions: The “Diabetes Comorbidome” represents the perfect instrument for determining the prevalence of comorbidities and the strength of their relationship with risk of death, as well as the need for an effective treatment for improving clinical outcomes