Forced oscillation assessment of respiratory mechanics in ventilated patients

The forced oscillation technique (FOT) is a method for non-invasively assessing respiratory mechanics that is applicable both in paralysed and non-paralysed patients. As the FOT requires a minimal modification of the conventional ventilation setting and does not interfere with the ventilation protocol, the technique is potentially useful to monitor patient mechanics during invasive and noninvasive ventilation. FOT allows the assessment of the respiratory system linearity by measuring resistance and reactance at different lung volumes or end-expiratory pressures. Moreover, FOT allows the physician to track the changes in patient mechanics along the ventilation cycle. Applying FOT at different frequencies may allow the physician to interpret patient mechanics in terms of models with pathophysiological interest. The current methodological and technical experience make possible the implementation of portable and compact computerised FOT systems specifically addressed to its application in the mechanical ventilation setting

Estudi de validació d'un instrument d'avaluació postural (SAM, spinal analysis machine)

Introducció: La posició bípeda és controlada pel sistema nerviós central, que recluta articulacions, lligaments, tendons i músculs especialitzats, i assegura una oscil·lació corporal i una despesa energètica mínimes. El desequilibri postural genera contraccions musculars compensatòries que alteren la biomecànica corporal i produeixen canvis degeneratius precoços i lesions de sobrecàrrega, especialment en la població practicant d'esport. Les revisions posturals freqüents podrien detectar alteracions i ajudar a prevenir-ne les conseqüències duradores. Objectiu: Valorar la fiabilitat intraobservador i interobservador de l'instrument d'avaluació postural SAM (spinal analysis machine), que consta d'una estructura metàl·lica amb dues balances per als peus, dues cintes mètriques, un fil vertical i tres d'horitzontals per mesurar la inclinació lateral del cos i l'altura dels mastoides, les espatlles i les crestes ilíaques. Subjectes i mètodes: Van participar-hi 21 jugadores de basquetbol d'edats compreses entre 14 i 15 anys, i 2 examinadors, que van fer 2 els mesuraments amb un interval de 7 dies. Per a l'anàlisi estadística es va utilitzar la prova de la t d'Student per a variables numèriques emparellades i per a l'estudi de les variances es va utilitzar l'ANOVA. Resultats: En l'anàlisi intraobservador no va haver-hi diferència significativa entre les dues lectures (p < 0,05); en l'anàlisi interobservador va haver-hi una diferència significativa entre les lectures dels paràmetres horitzontals, però no es va trobar diferència significativa entre els mesuraments de la distribució de pes i de la inclinació lateral del cos (p < 0,05). Conclusió: Considerant la fiabilitat intraobservador i el seu cost relativament baix, el SAM es pot utilitzar clínicament per valorar la posició estàtica abans i després d'intervencions terapèutiques i per a estudis longitudinals

Estudio de validación de un instrumento de evaluación postural (SAM, spinal analysis machine)

Introducción: La postura bípeda está controlada por el sistema nervioso central, que recluta articulaciones, ligamentos, tendones y músculos especializados, asegurando una oscilación corporal y un gasto energético mínimos. El desequilibrio postural genera contracciones musculares compensatorias que alteran la biomecánica corporal y producen cambios degenerativos precoces y lesiones de sobrecarga, especialmente en la población practicante de deporte. Los chequeos posturales frecuentes podrían detectar alteraciones y ayudar en la prevención de sus consecuencias duraderas. Objetivo: Valorar la fiabilidad intra e y interobservador del instrumento de evaluación postural SAM (spinal analysis machine), que consta de una estructura metálica con dos balanzas para los pies, dos cintas métricas, un hilo vertical y tres horizontales para medir la inclinación lateral del cuerpo y la altura de los mastoides, los hombros y las crestas ilíacas. Sujetos y métodos: Participaron 21 jugadoras de baloncesto con edades comprendidas entre los 14 y los 15 años, y 2 examinadores que hicieron 2 mediciones con un intervalo de 7 días. Para el análisis estadístico se utilizó la prueba de la t de Student para variables numéricas apareadas y para el estudio de las varianzas se usó el ANOVA. Resultados: En el análisis intraobservador no hubo diferencia significativa entre las dos lecturas (p < 0,05); en el interobservador hubo una diferencia significativa entre las lecturas de los parámetros horizontales pero no se encontró diferencia significativa entre las mediciones de la distribución de peso y de la inclinación lateral del cuerpo (p < 0,05). Conclusión: Considerando la fiabilidad intraobservador y su coste relativamente bajo, la SAM se puede utilizar clínicamente para valorar la postura estática antes y después de intervenciones terapéuticas y para estudios longitudinales

Technology for noninvasive mechanical ventilation: looking into the black box

Current devices for providing noninvasive respiratory support contain sensors and built-in intelligence for automatically modifying ventilation according to the patient's needs. These devices, including automatic continuous positive airway pressure devices and noninvasive ventilators, are technologically complex and offer a considerable number of different modes of ventilation and setting options, the details of which are sometimes difficult to capture by the user. Therefore, better predicting and interpreting the actual performance of these ventilation devices in clinical application requires understanding their functioning principles and assessing their performance under well controlled bench test conditions with simulated patients. This concise review presents an updated perspective of the theoretical basis of intelligent continuous positive airway pressure and noninvasive ventilation devices, and of the tools available for assessing how these devices respond under specific ventilation phenotypes in patients requiring breathing support

Low-cost, open-source device for simultaneously subjecting rodents to different circadian cycles of light, food, and temperature

Exposure of experimental rodents to controlled cycles of light, food, and temperature is important when investigating alterations in circadian cycles that profoundly influence health and disease. However, applying such stimuli simultaneously is difficult in practice. We aimed to design, build, test, and open-source describe a simple device that subjects a conventional mouse cage to independent cycles of physiologically relevant environmental variables. The device is based on a box enclosing the rodent cage to modify the light, feeding, and temperature environments. The device provides temperature-controlled air conditioning (heating or cooling) by a Peltier module and includes programmable feeding and illumination. All functions are set by a user-friendly front panel for independent cycle programming. Bench testing with a model simulating the CO2 production of mice in the cage showed: a) suitable air renewal (by measuring actual ambient CO2), b) controlled realistic illumination at the mouse enclosure (measured by a photometer), c) stable temperature control, and d) correct cycling of light, feeding, and temperature. The cost of all the supplies (retail purchased by e-commerce) was <300 US$. Detailed technical information is open-source provided, allowing for any user to reliably reproduce or modify the device. This approach can considerably facilitate circadian research since using one of the described low-cost devices for any mouse group with a given light-food-temperature paradigm allows for all the experiments to be performed simultaneously, thereby requiring no changes in the light/temperature of a general-use laboratory

Experimental Models to Study End-Organ Morbidity in Sleep Apnea: Lessons Learned and Future Directions.

Sleep apnea (SA) is a very prevalent sleep breathing disorder mainly characterized by intermittent hypoxemia and sleep fragmentation, with ensuing systemic inflammation, oxidative stress, and immune deregulation. These perturbations promote the risk of end-organ morbidity, such that SA patients are at increased risk of cardiovascular, neurocognitive, metabolic and malignant disorders. Investigating the potential mechanisms underlying SA-induced end-organ dysfunction requires the use of comprehensive experimental models at the cell, animal and human levels. This review is primarily focused on the experimental models employed to date in the study of the consequences of SA and tackles 3 different approaches. First, cell culture systems whereby controlled patterns of intermittent hypoxia cycling fast enough to mimic the rates of episodic hypoxemia experienced by patients with SA. Second, animal models consisting of implementing realistic upper airway obstruction patterns, intermittent hypoxia, or sleep fragmentation such as to reproduce the noxious events characterizing SA. Finally, human SA models, which consist either in subjecting healthy volunteers to intermittent hypoxia or sleep fragmentation, or alternatively applying oxygen supplementation or temporary nasal pressure therapy withdrawal to SA patients. The advantages, limitations, and potential improvements of these models along with some of their pertinent findings are reviewed

Gas Partial Pressure in Cultured Cells: Patho-Physiological Importance and Methodological Approaches

Gas partial pressures within the cell microenvironment are one of the key modulators of cell pathophysiology. Indeed, respiratory gases (O2 and CO2) are usually altered in respiratory diseases and gasotransmitters (CO, NO, H2S) have been proposed as potential therapeutic agents. Investigating the pathophysiology of respiratory diseases in vitro mandates that cultured cells are subjected to gas partial pressures similar to those experienced by each cell type in its native microenvironment. For instance, O2 partial pressures range from ∼13% in the arterial endothelium to values as low as 2–5% in cells of other healthy tissues and to less than 1% in solid tumor cells, clearly much lower values than those used in conventional cell culture research settings (∼19%). Moreover, actual cell O2 partial pressure in vivo changes with time, at considerably different timescales as illustrated by tumors, sleep apnea, or mechanical ventilation. Unfortunately, the conventional approach to modify gas concentrations at the above culture medium precludes the tight and exact control of intra-cellular gas levels to realistically mimic the natural cell microenvironment. Interestingly, well-controlled cellular application of gas partial pressures is currently possible through commercially available silicone-like material (PDMS) membranes, which are biocompatible and have a high permeability to gases. Cells are seeded on one side of the membrane and tailored gas concentrations are circulated on the other side of the membrane. Using thin membranes (50–100 μm) the value of gas concentration is instantaneously (<0.5 s) transmitted to the cell microenvironment. As PDMS is transparent, cells can be concurrently observed by conventional or advanced microscopy. This procedure can be implemented in specific-purpose microfluidic devices and in settings that do not require expensive or complex technologies, thus making the procedure readily implementable in any cell biology laboratory. This review describes the gas composition requirements for a cell culture in respiratory research, the limitations of current experimental settings, and also suggests new approaches to better control gas partial pressures in a cell culture

Multifactorial assessment and targeted intervention in nutritional status among the older adults: a randomized controlled trial: the Octabaix study

Background: Malnutrition is frequent among older people and is associated with morbi-mortality.he aim of the study is to assess the effectiveness of a multifactorial and multidisciplinary intervention in the nutritional status among the elderly. Methods: Randomized, single-blind, parallel-group, clinical trial conducted from January 2009 to December 2010 in seven primary health care centers in Baix Llobregat (Barcelona). Of 696 referred people, born in 1924, 328 subjects were randomized to an intervention group or a control group. The intervention model used an algorithm and was multifaceted for both the patients and their primary care providers. The main outcome was improvement in nutritional status assessed by Mini Nutritional Assessment (MNA). Data analyses were done by intention-to-treat. Results: Two-year assessment was completed for 127 patients (77.4%) in the intervention group and 98 patients (59.7%) in the control group. In the adjusted linear mixed models for MNA, intervention showed no significant effect during all follow-up period with −0.21 (CI: − 0.96; 0.26). In subjects with nutritional risk (MNA ≤ 23.5 / 30) existed a tendency towards improvement in MNA score 1.13 (95% CI −0.48; 2.74) after 2 years. Conclusion: A universal multifactorial assessment and target intervention over a two year period in subjects at nutritional risk showed a tendency to improve nutrition but not in the rest of community-dwelling studied subjects. Cognitive impairment was an independent factor strongly associated with a decline in nutritional status