Functional imaging of airway distensibility

The physiological function of the respiratory system is essential in distending airway smooth muscle and maintaining airway patency. Deep inspirations can reverse contracted airways and protect airways from subsequent bronchospastic stimuli. Obstructive lung diseases may lead to impairment of the beneficial effects of lung inflation through either change in the airway wall or lung parenchyma. Conventional pulmonary function measurements are unable to assess airway stiffness, based on changes in airway size with lung inflation (distensibility). However, high-resolution computed tomography (HRCT) is unique in that it can be used to measure airway distensibility in animals and in humans. Funct…

Genome-wide Analyses Identify KIF5A as a Novel ALS Gene

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Airways Hyperresponsiveness and the Effects of Lung Inflation

Lung inflation has a beneficial effect on the airways of healthy subjects. It acts as a bronchoprotector, that is to prevent bronchoconstriction, and as a bronchodilator, in that it reverses bronchial obstruction. The bronchoprotective effect of deep inspiration is more potent than the bronchodilatory one, and the two phenomena appear to advocte different mechanisms. Asthmatics and rhinitics with airways hyperresponsiveness show an impairment in bronchoprotection induced by deep breaths, whereas the bronchodilatory effect, although reduced, is still effective. The lack of the bronchoprotective effect of deep inspiration may contribute to the development of airways hyperresponsiveness. The m…

High-Resolution Computed Tomographic Evaluation of Airway Distensibility and the Effects of Lung Inflation on Airway Caliber in Healthy Subjects and Individuals with Asthma

The effects of a deep inspiration (DI) in individuals with asthma differ from those observed in healthy subjects. It has been postulated that the beneficial effect of lung inflation is mediated by airway stretch. One hypothesis to explain the defects in the function of lung inflation in asthma is that a DI may be unable to stretch the airways. This may result from attenuation of the tethering forces between the airways and the surrounding parenchyma. In the current study, we used high-resolution computed tomography (HRCT) to examine the ability of a DI to distend the airways of subjects with asthma (n = 10) compared with healthy subjects (n = 9) at baseline and after increasing airway tone …

The hidden burden of severe asthma: from patient perspective to new opportunities for clinicians

Severe asthma is an important topic in respiratory diseases, due to its high impact on morbidity and mortality as well as on health-care resources. The many challenges that still exist in the management of the most difficult-to-treat forms of the disease, and the acknowledgement of the existence of unexplored areas in the pathophysiological mechanisms and the therapeutic targets represent an opportunity to gather experts in the field with the immediate goals to summarize current understanding about the natural history of severe asthma and to identify gaps in knowledge and research opportunities, with the aim to contribute to improved medical care and health outcomes. This article is a conse…

The Pseudo-variable Extrathoracic Obstruction Flow Volume Loop Pattern In Double Lung And Heart Lung Transplantation

The bronchodilation response to deep inspiration in asthma is dependent on airway distensibility and air trapping

In healthy individuals, deep inspirations (DIs) have a potent bronchodilatory ability against methacholine (MCh)-induced bronchoconstriction. This is variably attenuated in asthma. We hypothesized that inability to bronchodilate with DIs is related to reduced airway distensibility. We examined the relationship between DI-induced bronchodilation and airway distensibility in 15 asthmatic individuals with a wide range of baseline lung function [forced expired volume in 1 s (FEV1) = 60–99% predicted]. After abstaining from DIs for 20 min, subjects received a single-dose MCh challenge and then asked to perform DIs. The effectiveness of DIs was assessed by the ability of the subjects to improve …

The airway response to deep inspirations decreases with COPD severity and is associated with airway distensibility assessed by computed tomography.

In patients with mild chronic obstructive pulmonary disease (COPD), the effect of deep inspirations (DIs) to reverse methacholine-induced bronchoconstriction is largely attenuated. In this study, we tested the hypothesis that the effectiveness of DI is reduced with increasing disease severity and that this is associated with a reduction in the ability of DI to distend the airways. Fifteen subjects [Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I–II: n = 7; GOLD stage III–IV: n = 8] underwent methacholine bronchoprovocation in the absence of DI, followed by DI. The effectiveness of DI was assessed by their ability to improve inspiratory vital capacity and forced expira…

Airway distensibility by HRCT in asthmatics and COPD with comparable airway obstruction.

Introduction: Decreased airway distensibility (AD) in response to deep inspirations, as assessed by HRCT, has been associated with the severity of asthma and COPD. Aims: The current study was designed to compare the magnitude of AD by HRCT in individuals with asthma and COPD with comparable degrees of bronchial obstruction, and to explore factors that may influence it. Results: We enrolled a total of 12 asthmatics (M/F:7/5) and 8 COPD (7/1) with comparable degree of bronchial obstruction (FEV1% predicted mean±SEM: 69.1 ± 5.2% and 61.2 ± 5.0%, respectively; p = 0.31). Each subject underwent chest HRCT at FRC and at TLC. A total of 701 airways (range 20 to 38 airway per subject; 2.0 to 23.1 m…