Ventilation heterogeneity in obesity.

Obesity is associated with important decrements in lung volumes. Despite this, ventilation remains normally or near normally distributed at least for moderate decrements in functional residual capacity (FRC). We tested the hypothesis that this is because maximum flow increases presumably as a result of an increased lung elastic recoil. Forced expiratory flows corrected for thoracic gas compression volume, lung volumes, and forced oscillation technique at 5-11-19 Hz were measured in 133 healthy subjects with a body mass index (BMI) ranging from 18 to 50 kg/m(2). Short-term temporal variability of ventilation heterogeneity was estimated from the interquartile range of the frequency distribution of the difference in inspiratory resistance between 5 and 19 Hz (R5-19_IQR). FRC \% predicted negatively correlated with BMI (r = -0.72, P < 0.001) and with an increase in slope of either maximal (r = -0.34, P < 0.01) or partial flow-volume curves (r = -0.30, P < 0.01). Together with a slight decrease in residual volume, this suggests an increased lung elastic recoil. Regression analysis of R5-19_IQR against FRC \% predicted and expiratory reserve volume (ERV) yielded significantly higher correlation coefficients by nonlinear than linear fitting models (r(2) = 0.40 vs. 0.30 for FRC \% predicted and r(2) = 0.28 vs. 0.19 for ERV). In conclusion, temporal variability of ventilation heterogeneities increases in obesity only when FRC falls approximately below 65\% of predicted or ERV below 0.6 liters. Above these thresholds distribution is quite well preserved presumably as a result of an increase in lung recoil

Mechanical correlates of dyspnea in bronchial asthma.

We hypothesized that dyspnea and its descriptors, that is, chest tightness, inspiratory effort, unrewarded inspiration, and expiratory difficulty in asthma reflect different mechanisms of airflow obstruction and their perception varies with the severity of bronchoconstriction. Eighty-three asthmatics were studied before and after inhalation of methacholine doses decreasing the 1-sec forced expiratory volume by ~15% (mild bronchoconstriction) and ~25% (moderate bronchoconstriction). Symptoms were examined as a function of changes in lung mechanics. Dyspnea increased with the severity of obstruction, mostly because of inspiratory effort and chest tightness. At mild bronchoconstriction, multivariate analysis showed that dyspnea was related to the increase in inspiratory resistance at 5 Hz (R 5) (r (2) = 0.10, P = 0.004), chest tightness to the decrease in maximal flow at 40% of control forced vital capacity, and the increase in R 5 at full lung inflation (r (2) = 0.15, P = 0.006), inspiratory effort to the temporal variability in R 5-19 (r (2) = 0.13, P = 0.003), and unrewarded inspiration to the recovery of R 5 after deep breath (r (2) = 0.07, P = 0.01). At moderate bronchoconstriction, multivariate analysis showed that dyspnea and inspiratory effort were related to the increase in temporal variability in inspiratory reactance at 5 Hz (X 5) (r (2) = 0.12, P = 0.04 and r (2) = 0.18, P &lt; 0.001, respectively), and unrewarded inspiration to the decrease in X 5 at maximum lung inflation (r (2) = 0.07, P = 0.04). We conclude that symptom perception is partly explained by indexes of airway narrowing and loss of bronchodilatation with deep breath at low levels of bronchoconstriction, but by markers of ventilation heterogeneity and lung volume recruitment when bronchoconstriction becomes more severe

Inhalation therapy in the next decade : Determinants of adherence to treatment in asthma and COPD

Peer reviewedPublisher PD

Reduced Order Modeling for Real-Time Monitoring of Structural Displacements due to Electromagnetic Forces in Large Scale Tokamaks

The real-time monitoring of the structural displacement of the Vacuum Vessel (VV) of thermonuclear fusion devices caused by electromagnetic (EM) loads is of great interest. In this paper, Model Order Reduction (MOR) is applied to the Integral Equation Methods (IEM) and the Finite Elements Method (FEM) to develop Electromagnetic and Structural Reduced Order Models (ROMs) compatible with real-time execution which allows for the real-time monitoring of strain and displacement in critical positions of Tokamaks machines. Low-rank compression techniques based on hierarchical matrices are applied to reduce the computational cost during the offline stage when the ROMs are constructed. Numerical results show the accuracy of the approach and demonstrate the compatibility with real-time execution in standard hardware

Mixed Proper Orthogonal Decomposition with Harmonic Approximation for Parameterized Order Reduction of Electromagnetic Models

This paper presents some preliminary investigations on a hybrid Model Order Reduction approach for parameter-dependent electromagnetic systems. Starting from an integral equation formulation of the field problem, we introduce a first level of compression based on the well-established Proper Orthogonal Decomposition (POD). The result is a small-scale approximation of the full-order discrete field formulation, which retains an explicit dependence on the set of free parameters defining the geometry. The evaluation of the reduced model for arbitrary parameter configurations remains very expensive, as it requires the construction of the full system equations before its projection onto a lower-dimensional space. This problem is solved by constructing a surrogate macromodel of the parameterized reduced-order system through a multivariate Fourier approximation. Numerical results applied to a moving coil over a finite ground plane show model compression above 99% while preserving accuracy on currents and fields within 1%

Supramolecular hydrogels based on custom-made poly(ether urethane)s and cyclodextrins as potential drug delivery vehicles: design and characterization

The design of supramolecular (SM) hydrogels based on host-guest complexes represents an effective strategy to develop drug delivery systems. In this work, we designed SM hydrogels based on α-cyclodextrin and high-molar mass amphiphilic poly(ether urethane)s (PEUs, ) based on Poloxamer® 407 and differing in their chain extender. The successful formation of poly(pseudo)rotaxanes and their supramolecular interactions were chemically demonstrated. Then, self-healing (80-100% mechanical recovery) supramolecular hydrogels were developed by mixing PEU and α-cyclodextrin solutions at different concentrations. Stability in physiological-like environment and mechanical properties improved with increasing α-cyclodextrin content (9-10% w/v), meanwhile gelation time decreased. A synergistic effect of poly(pseudo)rotaxanes crystals and PEU micellar structures on gel properties was observed: the first were predominant at low PEU concentrations (1-5% w/v), while the latter prevailed at high PEU concentrations (7-9% w/v). Increasing PEU concentration led to gels with increased dissolution rate, not-fully developed networks and slight cytotoxicity, meanwhile residence time in aqueous media improved (>7 d). At low PEU concentrations (1-5% w/v), cytocompatible gels (100% cell viability) were obtained, which maintained their shape in aqueous medium up to 5 d and completely dissolved within 7 d. PEU chemical composition affected PEU/α-cyclodextrin interactions, with longer gelation time and lower mechanical properties in gels based on PEU with pendant functionalities. Gels progressively released a model molecule (fluorescein isothiocyanate-dextran) within 3-4 days with no initial burst release. We thus demonstrated the suitability of custom-made PEUs as constituent of SM hydrogels with α-cyclodextrin and the high potential of the resulting systems for drug delivery applications

Trust levels toward health care and government: insights from TrustMe, an Italian cross-sectional study

Introduction: Negative trends of trust in governments have been described around the world. This study aimed to describe the distrust level in the National Health Service (NHS) and in governmental management of the pandemic, one year after the start of the COVID-19 vaccination campaign.&nbsp; Methods: A survey was distributed in February 2022 among a convenience sample. Outcomes were measured through validated tools: Revised Health Care System Distrust Scale, and the COVID-SCORE-10 questionnaire. Associations were assessed using multiple linear regression models. Results: A total of 2111 questionnaires were collected (54.8% female, median age 43 years [IQR=34-50]). Distrust in the NHS had a median level of 12 [IQR=10-14], while trust in the government had a level of 47 [IQR=35-60]. COVID-19 vaccine hesitancy, high educational attainment, worse economic status, low conventional and digital health literacy, as well as the presence of conspiracy thoughts and distrust in the NHS were significantly associated with lower trust in government during the COVID-19 pandemic. Lack of trust in governmental actions, along with low education and health literacy, as well as the presence of conspiracy thoughts and worse perceptions of one's own health, were associated with greater distrust in the NHS. Conclusions: Overall, low levels of trust in both the government and the NHS have emerged. Since the determinants of reduced trust in institutions can be very diverse and that such levels of distrust after a pandemic can last for an entire generation, tailored interventions are needed to rebuild adequate levels of trust in institutions among the population

Orthopedic implants affect the electric field induced by switching gradients in MRI

PurposeTo investigate whether the risk of peripheral nerve stimulation increases in the presence of bulky metallic prostheses implanted in a patient's body.MethodsA computational tool was used to calculate the electric field (E-field) induced in a realistic human model due to the action of gradient fields. The calculations were performed both on the original version of the anatomical model and on a version modified through "virtual surgery" to incorporate knee, hip, and shoulder prostheses. Five exam positions within a body gradient coil and one position using a head gradient coil were simulated, subjecting the human model to the readout gradient from an EPI sequence. The induced E-field in models with and without prostheses was compared, focusing on the nerves and all other tissues (both including and excluding the bones from the analysis).ResultsIn the nerves, the most pronounced increase in the E-field (+24%) was observed around the knee implant during an abdominal MRI (Y axis readout). When extending the analysis to encompass all tissues (excluding bones), the greatest amplification (+360%) occurred around the knee implant during pelvic MRI (Z axis readout). Notable increases in E-field peaks were also identified around the shoulder and hip implants in multiple scenarios.ConclusionBased on the presented results, further investigations aimed at quantifying the threshold of nerve stimulation in the presence of bulky implants are desirable