Comparison Between Pressure Swing Adsorption and Liquid Oxygen Enrichment Techniques in the Atacama Large Millimeter/Submillimeter Array Facility at the Chajnantor Plateau (5,050 m).

The Chilean workforce has over 200,000 people that are intermittently exposed to altitudes over 4,000 m. In 2012, the Ministry of Health provided a technical guide for high-altitude workers that included a series of actions to mitigate the effects of hypoxia. Previous studies have shown the positive effect of oxygen enrichment at high altitudes. The Atacama Large Millimeter/submillimeter Array (ALMA) radiotelescope operates at 5,050 m [Array Operations Site (AOS)] and is the only place in the world where pressure swing adsorption (PSA) and liquid oxygen technologies have been installed at a large scale. These technologies reduce the equivalent altitude by increasing oxygen availability. This study aims to perform a retrospective comparison between the use of both technologies during operation in ALMA at 5,050 m. In each condition, variables such as oxygen (O2), temperature, and humidity were continuously recorded in each AOS rooms, and cardiorespiratory variables were registered. In addition, we compared portable O2 by using continuous or demand flow during outdoor activities at very high altitudes. The outcomes showed no differences between production procedures (PSA or liquid oxygen) in regulating oxygen availability at AOS facilities. As a result, big-scale installations have difficulties reaching the appropriate O2 concentration due to leaks in high mobility areas. In addition, the PSA plant requires adequacy and maintenance to operate at a very high altitude. A continuous flow of 2-3 l/min of portable O2 is recommended at 5,050 m.

Estrategias para el empleo optimizado de la neuroimagenología en pacientes con traumatismo encéfalo craneano: puesta al día / Strategies for the optimized use of neuroimaging in patients with head trauma cranial: update

INTRODUCTION: Introduction of current neuroimaging technologies has been essential for the agile and effective diagnosis of cranial brain injuries. However, for various reasons there is a tendency to indiscriminate use. A review of the topic was made aimed at providing an update on the recommended strategies for the optimized use of these technologies. Material and method: A review of the topic of the last five years was made, using the Medline / Pubmed and SciELO platforms of complete articles, in English and Spanish. We also included relevant articles, published in previous years, located in previous bibliographic reviews carried out by the authors. CONCLUSIONS: Routine study with CT scan in all patients with head trauma is not cost effective, should be used in patients with Glasgow less than 15 points or in those with Glasgow of 15 points and risk factors of intracranial injury. Its use as a form of neuromonitoring is similarly useful, but on a selective basis. Magnetic Resonance Imaging is especially useful in the mediate or late periods of cranial trauma, in patients with clinical tomographic incongruences, very useful to establish prognosis in diffuse traumas and intracranial complications. Neurosonology is a useful tool for therapeutic decision.

Diagnóstico diferencial entre Glioma y Absceso cerebrales: enseñanzas a partir de un caso / Differential diagnosis between Glioma and Abscess of the brain: teachings from a case

Development of neuroimaging in the last decades has revolutionized the neurological diagnosis, however for they interpretation clinical picture of the patient remains as a relevant aspect. Clinical case: a 30-year-old male patient with recent epileptic seizures, Jaksonian type, secondarily generalized, with no relevant history and normal neurological examination was presented. Initially a Magnetic Resonance of the brain was performed, the case was interpreted as Brain Abscess and treatment with intravenous antimicrobials was instituted for three weeks. A further analysis of the case revolves the diagnosis towards the possibility of a high degree malignant cerebral glioma, which was verified with the accomplishment of a craneotomy and biopsy. Conclusions: focal structural lesions of the brain, such as those caused by neuroepithelial tumors and abscesses, are among the most common causes of Epileptic Syndrome in adulthood. To date, there are no pathognomonic signs in the neuroimagenological differential diagnosis between the two entities. Despite the help of some advanced Magnetic Resonance techniques, the clinical correlation remains as the cornerstone for correct etiological interpretation, as well as pathological examination for the definitive diagnosis of both lesions.

Presentación sincrónica de tumor epidermoides intracraneal y absceso cerebral: reporte de un caso / Synchronous presentation of intracranial epidermoid tumor and brain abscess: case report

Introducción: Un paciente con tumor epidermoides intracraneal extradural con presentación sincrónica con absceso cerebral, sin antecedentes de trauma craneal penetrante, no ha sido reportado con anterioridad en la revisión del tema realizada por los autores. Se presenta un caso con estas características y se exponen consideraciones sobre el diagnóstico y el tratamiento. Caso clínico: Paciente femenina, de 48 años de edad, con antecedentes de cefalea crónica y tumor craneal palpable en región frontal izquierda. Los estudios humorales fueron normales. La RNM craneal mostró dos imágenes en anillo yuxtapuestas, extra e intraaxial de forma respectiva. En la cirugía se encontró tumor perlado extradural sin evidencia a la inspección de tumor intradural, se comprobó en el examen histopatológico tumor epidermoides. En los controles imagenológicos posoperatorios se descubrió la persistencia de la lesión intraaxial, en anillo, frontal izquierda. Una segunda cirugía evidenció un absceso cerebral de ubicación subcortical y se efectuó la resección radical. La evolución fue favorable, sin secuelas después de cuatro meses de seguimiento. Conclusiones: Se reportó un caso infrecuente, donde se presentó de forma sincrónica un tumor epidermoides extradural frontal izquierdo y absceso cerebral frontal ipsilateral, sin relación de continuidad ni comunicación fistulosa demostrada en las neuroimágenes ni en la exploración quirúrgica.

Introduction: A patient with intracranial extradural epidermoid tumor with synchronous presentation with brain abscess and no history of penetrating head trauma, has not been previously reported in the revision of the subject made by the authors. A case with these characteristics is presented and also considerations about diagnosis and treatment. Case report: A 48-yearold female patient, with a history of chronic headache and cranial palpable tumor in left frontal region. Humoral studies were normal. Cranial MRI showed two juxtaposed, extra and intraaxial ring images. At surgery an extradural pearly tumor without evidence of intradural tumor on inspection was found, biopsy showed an epidermoid tumor. Persistence of intraaxial ring lesion in left frontal lobe was showed in postoperative imaging controls. A second surgery discovered a subcortical brain abscess and radical resection was done. Patient outcome has been without sequelae after four months of follow-up. Conclusions: An uncommon case where reported with extradural left frontal epidermoid tumor and ipsilateral frontal brain abscess synchronously presented, neither continuity nor fistulous communication were demonstrated on neuroimaging or surgical exploration.

Algoritmo para la tomografía secuencial de cráneo en pacientes con traumatismo encéfalocraneano / Algorithm for sequential cranial tomography in patients with encephalocranial trauma

Introducción: el monitoreo imagenológico estructural del encéfalo en pacientes con traumatismo encéfalocraneano se practica habitualmente de forma no protocolizada. Se requieren estrategias fundamentadas en la evidencia científica. Se realizó una investigación con el objetivo de implementar un algoritmo para la realización de tomografía computarizada de cráneo secuencial en pacientes con traumatismo encéfalocraneano. Material y Métodos: Se practicó un estudio cuasiexperimental, con una serie continua de lesionados encéfalocraneanos que fueron estudiados al menos en dos ocasiones durante la fase aguda con tomografía computarizada de cráneo. La variable dependiente fue el cambio imagenológico significativo. Se aplicaron técnicas de Chi-cuadrado, ANOVA y regresión logística. Con los datos obtenidos se diseñó y aplicó un algoritmo de manejo. Resultados: Se estudiaron 84 pacientes, el 16, 7 por ciento de la serie mostró cambios tomográficos significativos en los estudios secuenciales. Las principales variables involucradas en el pronóstico fueron los mecanismos de producción de alta energía, los síntomas persistentes, la escala de Marshall y el puntaje de Rotterdam iniciales. Con esta información se diseñó un algoritmo que homogenizó los criterios en cuanto a los momentos de realización y al grupo de traumatizados en los que no es útil esta práctica. Conclusiones: La aplicación del algoritmo contribuyó a optimizar la tomografía secuencial de cráneo en lesionados encéfalocraneanos.

Introduction: encephalic structural imaging monitoring by means of sequential CT scan of the head is an established practice, although carried out in a heterogeneous way in the different contexts due to inexistence of all necessary evidence to dictate standard. An investigation was performed to implement an algorithm for the application of sequential CT scan of the head in patients with head trauma. Material and Methods: A quasiexperimental study was practiced with all patients who suffer cerebral trauma, were hospital admitted and that were studied by means of head CT scan in two occasions at least in the same period of hospital admission. Systematization of the indications to perform sequential CT scan of the head was carried, then their application and later the evaluation of the behavior of variables by means of exploratory statistic, Chi-square, ANOVA and logistical regression. Based on data obtained and algorithm was designed and applied. Results: 84 patients were studied and the 16, 7 percent of the sample showed significant tomographic changes in the sequential studies. The group of patient more related with these changes was the one that presented persistent symptoms with initial Marshall III or IV. Main variables involved in the prognosis were high-speed mechanisms in the traumatism production, the persistence of symptoms and the initial Rotterdam score. Conclusions: Algorithm applied contributed to optimization of sequential CT scan of the head in patients with cerebral trauma.

Análisis y características de los stents farmacoactivos disponibles en la actualidad. Futuros desarrollos / Characteristics of currently available drug-eluting stents. Future developments

Los stents metálicos se desarrollaron para combatir el retroceso elástico, las complicaciones agudas y la reestenosis de la angioplastia con balón, pero crearon una nueva entidad, la restenosis intra-stent, ligada a múltiples factores. Entre ellos, las características clínicas del paciente y el tipo de lesión son inmodificables. Sin embargo, la técnica de implante y, muy particularmente, el diseño del stent han experimentado una gran transformación que ha desembocado en la nueva era de los stents recubiertos, stents liberadores de fármacos o el término que mejor los define, stents farmacoactivos. Estos nuevos stents son dispositivos muy complejos que involucran tecnología y diseño de la plataforma o stent, investigación y desarrollo en el terreno de los polímeros que actuan como transportadores y liberadores de los fármacos, y el propio fármaco que debe inhibir la proliferación neointimal. Si bien los primeros diseños, con 5 años de seguimiento clínico a sus espaldas, han mostrado una reducción significativa y sostenida de la reestenosis y las nuevas revascularizaciones frente a los stents metálicos convencionales, también han mostrado debilidades y sombras, que deben irse corrrigiendo en las próximas generaciones de stents farmacoactivos. En esta revisión se lleva a cabo un análisis detallado de la importancia del diseño del stent, se hace una incursión breve en el mundo de los polímeros, sus tipos y su funcionamiento, y se describen los fármacos empleados en los stents farmacoactivos. Se analizan las características y los resultados clínicos y angiográficos de los stents actualmente disponibles o en fase de estudio, y se abre una ventana hacia los futuros desarrollos (AU)

Metallic stents were developed to minimize the elastic recoil, acute complications, and restenosis that occur with balloon angioplasty. However, they also led to the new problem of in-stent restenosis, which is associated with a number of factors, including some that can not be modified, such as the patient’s clinical characteristics and the type of lesion. Nevertheless, stent implantation techniques and, most importantly, stent design have undergone an enormous transformation, which has led to the new era of coated stents and drug-eluting stents, or, in the terminology that best defines them, active stents. These new stents are very sophisticated devices, which involve innovative stent technology and design, and research and development into polymer coatings for drug storage and release and into the drugs for inhibiting intimal thickening themselves. Although first-generation drug-eluting stents, which have already been followed up clinically for 5 years, have resulted in significant and sustained improvements in the rates of restenosis and revascularization compared with bare metal stents, they have also been found to have weaknesses and disadvantages that will have to be corrected in future generations of drug-eluting stents. This review contains a detailed description of the importance of stent design, involves a brief exploration of the world of polymers and how they function, and surveys the different drugs used in drugeluting stents. It also summarizes the characteristics of and clinical and angiographic data on the drug-eluting stents that are either currently available or being investigated in clinical trails, and provides a glimpse of future developments (AU)