Airway pressure morphology and respiratory muscle activity during end-inspiratory occlusions in pressure support ventilation.

BACKGROUND: The driving pressure of the respiratory system is a valuable indicator of global lung stress during passive mechanical ventilation. Monitoring lung stress in assisted ventilation is indispensable, but achieving passive conditions in spontaneously breathing patients to measure driving pressure is challenging. The accuracy of the morphology of airway pressure (Paw) during end-inspiratory occlusion to assure passive conditions during pressure support ventilation has not been examined. METHODS: Retrospective analysis of end-inspiratory occlusions obtained from critically ill patients during pressure support ventilation. Flow, airway, esophageal, gastric, and transdiaphragmatic pressures were analyzed. The rise of gastric pressure during occlusion with a constant/decreasing transdiaphragmatic pressure was used to identify and quantify the expiratory muscle activity. The Paw during occlusion was classified in three patterns, based on the differences at three pre-defined points after occlusion (0.3, 1, and 2 s): a "passive-like" decrease followed by plateau, a pattern with "clear plateau," and an "irregular rise" pattern, which included all cases of late or continuous increase, with or without plateau. RESULTS: Data from 40 patients and 227 occlusions were analyzed. Expiratory muscle activity during occlusion was identified in 79% of occlusions, and at all levels of assist. After classifying occlusions according to Paw pattern, expiratory muscle activity was identified in 52%, 67%, and 100% of cases of Paw of passive-like, clear plateau, or irregular rise pattern, respectively. The driving pressure was evaluated in the 133 occlusions having a passive-like or clear plateau pattern in Paw. An increase in gastric pressure was present in 46%, 62%, and 64% of cases at 0.3, 1, and 2 s, respectively, and it was greater than 2 cmH2O, in 10%, 20%, and 15% of cases at 0.3, 1, and 2 s, respectively. CONCLUSIONS: The pattern of Paw during an end-inspiratory occlusion in pressure support cannot assure the absence of expiratory muscle activity and accurate measurement of driving pressure. Yet, because driving pressure can only be overestimated due to expiratory muscle contraction, in everyday practice, a low driving pressure indicates an absence of global lung over-stretch. A measurement of high driving pressure should prompt further diagnostic workup, such as a measurement of esophageal pressure.

Sublingual Immunotherapy Dosing Regimens: What Is Ideal?

Sublingual immunotherapy (SLIT) is a treatment for allergic respiratory diseases that has demonstrated efficacy and safety. Several formulations of SLIT are now available worldwide for treatment of allergic rhinitis (AR). Grass tablets containing 15 to 25 µg of group 5 major allergen reduced combined AR symptoms and medication use by 23% to 41% in 3 treatment years and 2 follow-up years. Ragweed pollen tablets (12 µg of Ambrosia artemisiifolia 1) and liquid extracts (50 µg of Ambrosia artemisiifolia 1) reduced combined AR symptoms and medication use by 26% and 43%, respectively. House dust mite tablets containing 300 index of reactivity (16 µg of Dermatophagoides pteronyssinus 1 and 68 µg of Dermatophagoides farinae 1) reduced AR symptoms by 17.9% and 17.0% in 1 treatment year and 1 follow-up year, respectively. A different house dust mite tablet (12 standardized quality house dust mite) was able to reduce the risk of asthma exacerbation compared with placebo (hazard ratio, 0.69; 95% CI, 0.50-0.96). Most adverse events were local and mild to moderate in severity. For SLIT products reviewed herein, effective doses range from 1.12 to 84 µg of major allergen(s). However, allergen content is not uniformly standardized, can be expressed in arbitrary or proprietary units (depending on the manufacturer), and assays for determination of allergen content are highly variable. Thus, results from one study of a given product cannot be extrapolated to other products. Despite these limitations, this Clinical Management Review aims to provide practitioners with relevant information on the dosing of selected SLIT formulations in the treatment of allergic respiratory disease.

TRP functions in the broncho-pulmonary system.

The current understanding of the role of transient receptor potential (TRP) channels in the airways and lung was initially based on the localization of a series of such channels in a subset of sensory nerve fibers of the respiratory tract. Soon after, TRP channel expression and function have been identified in respiratory nonneuronal cells. In these two locations, TRPs regulate physiological processes aimed at integrating different stimuli to maintain homeostasis and to react to harmful agents and tissue injury by building up inflammatory responses and repair processes. There is no doubt that TRPs localized in the sensory network contribute to airway neurogenic inflammation, and emerging evidence underlines the role of nonneuronal TRPs in orchestrating inflammation and repair in the respiratory tract. However, recent basic and clinical studies have offered clues regarding the contribution of neuronal and nonneuronal TRPs in the mechanism of asthma, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cough, and other respiratory diseases.

Physical activity: do patients infected with HIV practice? How much? A systematic review.

Several studies have suggested that aerobic physical activity is safe and beneficial for HIV-infected adults. However, there is information lacking regarding whether HIV-infected patients practice physical activity and to what extent. Therefore, the aim of this systematic review was to determine the prevalence of physical activity, sedentary lifestyle or lack of physical activity in non-experimental conditions performed by HIV-infected subjects. The electronic search was conducted using Medline and EMBASE bibliographic databases and the platforms of Bireme, Ovid, Science Direct, High Wire and SCIELO from January 1990 to July 2011. Original observational studies were included. Of the 2,838 articles found, 48 met the inclusion criteria. Following data extraction and after reading the manuscripts, 24 were selected for systematic review. Of the 24 studies, most were cross-sectional studies. The average quality score using the modified Newcastle-Ottawa scale was 2.8±1.5. The diversity of methods used to assess physical activity precluded the calculated summary estimate of prevalence. The percentage of sedentary lifestyle was determined in 13 articles which conducted studies on HIV-infected individuals. The percentage of sedentary lifestyle or physical inactivity ranged from 19%to 73%, with the level determined by different methods. In conclusion, there are few well-designed studies with adequate sample size to represent the population of HIV-infected individuals. A pooled estimate could not be calculated due to the differences in physical activity measurements and definitions of physically active and non-active HIV-infected individuals.

Trastornos respiratorios del sueño en niños. Un problema de salud emergente / No disponible

El Síndrome de Apneas/Hipopneas durante el Sueño (SAHS) en los niños, es el máximo exponente de los Trastornos Respiratorios del Sueño en los niños (TRS) y se asocia con importante morbilidad neurocognitiva, cardiovascular y metabólica, existiendo actualmente evidencias de lesión de órganos diana y daño celular. La obesidad se ha convertido en un importante factor de riesgo en la patofisiología del SAHS infantil. El infradiagnóstico del SAHS en los niños, ha conducido a una preocupación creciente en el abordaje diagnósticoterapéutico integral, así como a la búsqueda de sistemas de diagnóstico más sencillos. El tratamiento de elección es la adenoamigdalectomia, sin embargo, las evidencias actuales hacen necesario la incorporación de tratamientos no quirúrgicos que permitan abordar las formas leves, el SAHS residual y los TRS asociados a síndromes malformativos (AU)

No disponible

Adverse effect of nano-silicon dioxide on lung function of rats with or without ovalbumin immunization.

BACKGROUND: The great advances of nanomaterials have brought out broad important applications, but their possible nanotoxicity and risks have not been fully understood. It is confirmed that exposure of environmental particulate matter (PM), especially ultrafine PM, are responsible for many lung function impairment and exacerbation of pre-existing lung diseases. However, the adverse effect of nanoparticles on allergic asthma is seldom investigated and the mechanism remains undefined. For the first time, this work investigates the relationship between allergic asthma and nanosized silicon dioxide (nano-SiO2). METHODOLOGY/PRINCIPAL FINDINGS: Ovalbumin (OVA)-treated and saline-treated control rats were daily intratracheally administered 0.1 ml of 0, 40 and 80 µg/ml nano-SiO2 solutions, respectively for 30 days. Increased nano-SiO2 exposure results in adverse changes on inspiratory and expiratory resistance (Ri and Re), but shows insignificant effect on rat lung dynamic compliance (Cldyn). Lung histological observation reveals obvious airway remodeling in 80 µg/ml nano-SiO2-introduced saline and OVA groups, but the latter is worse. Additionally, increased nano-SiO2 exposure also leads to more severe inflammation. With increasing nano-SiO2 exposure, IL-4 in lung homogenate increases and IFN-γ shows a reverse but insignificant change. Moreover, at a same nano-SiO2 exposure concentration, OVA-treated rats exhibit higher (significant) IL-4 and lower (not significant) IFN-γ compared with the saline-treated rats. The percentages of eosinophil display an unexpected result, in which higher exposure results lower eosinophil percentages. CONCLUSIONS/SIGNIFICANCE: This was a preliminary study which for the first time involved the effect of nano-SiO2 to OVA induced rat asthma model. The results suggested that intratracheal administration of nano-SiO2 could lead to the airway hyperresponsiveness (AHR) and the airway remolding with or without OVA immunization. This occurrence may be due to the Th1/Th2 cytokine imbalance accelerated by the nano-SiO2 through increasing the tissue IL-4 production.

[The relationship between the lung function and the level of TNF-α in serum in COPD department of respiratory].

AIM: To explore the relationship between the lung function and the level of TNF-α in serum in COPD. METHODS: 60 patients with COPD and 35 normal subjects were involved in the study. The serum TNF-α level was measured by ELISA and the lung function were determined. RESULTS: The level of TNF-α were significantly different in acute and stable COPD group, control group (P < 0.01). The levels of FEVI, FVC, FEVI/FVC and MMEF in acute and stable COPD group were significantly lower than those control group (P < 0.01). The levels of TNF-α was negatively correlated with FEVI, FVC, FEVI/FVC and MMEF (r = -0.586, -0.714, -0.527, -0.639, P < 0.05). CONCLUSION: The TNF-α are involved in airway inflammation and the pathogenetic process of COPD, and may influence the lung function.