Asthma and Lung Mechanics

Kaminsky, David A.; Chapman, David G.

doi:10.1002/cphy.c190020

Cited by 19 publications

(15 citation statements)

References 320 publications

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“…23 In addition, airway narrowing should increase airway resistance resulting in a drop in sGaw, as well as increased gas trapping from airway closure and insufficient time for exhalation, manifesting as a rise in RV. 24 Our study supports increasing evidence that using sGaw to diagnose AHR is clinically meaningful.…”

Section: Discussionsupporting

confidence: 86%

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Validation of the clinical utility of sGaw as a response variable in methacholine challenge testing

et al. 2022

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Background and Objective Airway hyperresponsiveness (AHR) is commonly assessed by a methacholine challenge test (MCT), during which a provocative concentration causing a 20% reduction in forced expiratory volume in 1 second (FEV1) (PC20) < 8 mg/ml is considered a positive response. However, a fall in specific airway conductance (sGaw) may also have clinical significance. The purpose of this study was to assess whether AHR determined by a provocative concentration causing a 40% reduction in sGaw (PC40) < 8 mg/ml corresponds to a clinical diagnosis of asthma. Methods We analysed the changes in spirometry, lung volumes and sGaw during MCT in 211 randomly selected patients being evaluated for AHR to support a clinical diagnosis of asthma. Results The mean (SD) age of the group was 53 (15) years, with 141 women (67%). Overall lung function was normal, with FEV1 = 92 (15) % predicted, total lung capacity = 97 (13) % predicted and sGaw = 0.19 (0.15–0.23) L/s/cm H2O/L, (median, 25–75 IQR). There were many more patients who responded by PC40 only (n = 120) than who responded by PC20 (n = 52). There was no significant difference in asthma diagnosis between the PC20 (98%) and PC40 (93%) groups, and we estimate 34% of patients with a diagnosis of asthma would have been classified as having no AHR if only the FEV1 criterion was used. Conclusion Changes in sGaw during MCT indicate clinically significant AHR in support of a clinical diagnosis of asthma among patients being evaluated for asthma.

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Section: Discussionsupporting

confidence: 86%

“…The mean (SD) age of the group was 53 (11) years, with 141 women (67%) and 70 men (33%). The median (25-75 IQR) BMI was 29 (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34) kg/m 2 . There were 80 (38%) current or former smokers, with a median use history of 15 The distribution of demographics among the four groups is shown in Table 1.…”

Section: Resultsmentioning

confidence: 99%

Validation of the clinical utility of sGaw as a response variable in methacholine challenge testing

et al. 2022

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“…In contrast, COPD displayed a higher peripheral airways resistance (assessed by R 5 −R 20 ) than asthma or bronchiectasis at the same FEV 1 level. These characteristics are consistent with the underlying pathophysiology of the diseases, as the airflow limitation manifested in asthma is a result of the pathological changes of both the large and small airways [20], while the airflow limitation of COPD largely refers to the pathological changes of the peripheral lung and airways [2]. These findings also indicate that oscillometry can offer more detailed information on the pathophysiology of obstructive airway diseases than spirometry, suggesting its potential usefulness in clinical evaluation.…”

Section: Characteristics Of Oscillometry In Asthma Copd Bronchiectasi...supporting

confidence: 62%

Clinical application of oscillometry in respiratory diseases: an impulse oscillometry registry

et al. 2022

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BackgroundRespiratory oscillometry is a promising complement to the traditional pulmonary function tests for its simplicity. The usefulness of oscillometry in adult clinical practice has not been clarified. This study aimed to analyse the characteristics and diagnostic performance of oscillometry in respiratory diseases, and explore the cut-offs of oscillometric parameters for severity grading.MethodsIn this multicentre registry of impulse oscillometry (IOS), IOS and spirometric data of healthy individuals and patients with respiratory diseases were collected and analysed. Linear mixed model analysis was performed to explore the effects of disease and FEV1 on oscillometric parameters.ResultsThe study included 567 healthy subjects, 781 asthmatic patients, 688 patients with chronic obstructive pulmonary disease (COPD), 109 patients with bronchiectasis, 40 patients with upper airway obstruction (UAO), and 274 patients with interstitial lung disease (ILD) in the analysis. Compared at the same FEV1 level, asthma, COPD, bronchiectasis, UAO, and ILD displayed different oscillometric characteristics. The z-score of resistance at 5 Hz (R5) was the best variable to identify respiratory diseases with a sensitivity of 62.4%–66.7% and a specificity of 81.5%–90.3%. With reference to the severity grading cut-offs of FEV1, the R5 z-score of 2.5 and 4 were defined as the cut-off values of moderate and severe increased R5.ConclusionRespiratory oscillometry is more appropriate to be a tool of evaluation instead of diagnosing for respiratory diseases. A Severity grading system of oscillometric parameters was developed to help the interpretation of oscillometry in clinical practice.

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“…10 ). 54 Alterations in ASM function may result in increased contractile force 55 56 or speed. 57 Airway remodeling may result in increased airway wall thickness and thus geometric enhancement of any degree of ASM contraction on airway narrowing.…”

Section: Airway Hyperresponsivenessmentioning

confidence: 99%

Respiratory System Dynamics

Kaminsky

Cockcroft

Davis

2023

Semin Respir Crit Care Med

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While static mechanical forces govern resting lung volumes, dynamic forces determine tidal breathing, airflow, and changes in airflow and lung volume during normal and abnormal breathing. This section will examine the mechanisms, measurement methodology, and interpretation of the dynamic changes in airflow and lung volume that occur in health and disease. We will first examine how the total work of breathing can be described by the parameters of the equation of motion, which determine the pressure required to move air into and out of the lung. This will include a detailed description of airflow characteristics and airway resistance. Next, we will review the changes in pressure and flow that determine maximal forced inspiration and expiration, which result in the maximal flow–volume loop and the clinically important forced expired volume in 1 second. We will also assess the mechanisms and interpretation of bronchodilator responsiveness, dynamic hyperinflation, and airways hyperresponsiveness.

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Asthma and Lung Mechanics

Abstract: This is the peer reviewed version of the following article: [Comprehensive Physiology, 2020Physiology, , 10, (3), pp. 975-1007 which has been published in final form at

Cited by 19 publications

References 320 publications

Validation of the clinical utility of sGaw as a response variable in methacholine challenge testing

Validation of the clinical utility of sGaw as a response variable in methacholine challenge testing

Clinical application of oscillometry in respiratory diseases: an impulse oscillometry registry

Respiratory System Dynamics

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