Controlled free breathing for multiple-breath nitrogen washout in asthma.

https://bit.ly/3lmri4A.

Within-session variability as quality control for oscillometry in health and disease.

Oscillometry is increasingly adopted in respiratory clinics, but many recommendations regarding measurement settings and quality control remain subjective. The aim of this study was to investigate the optimal number of measurements and acceptable within-session coefficient of variation (CoV) in health, asthma and COPD. 15 healthy, 15 asthma and 15 COPD adult participants were recruited.

Controlled free breathing for multiple breath nitrogen washout in healthy adults.

Multiple breath nitrogen washout (MBNW) quantifies ventilation heterogeneity. Two distinct protocols are currently used for MBNW testing: "controlled breathing", with targeted tidal volume ( ) and respiratory rate (RR); and "free breathing", with no constraints on breathing pattern. Indices derived from the two protocols (functional residual capacity (FRC), lung clearance index (LCI), , ) have not been directly compared in adults.

Contribution of peripheral airway function to changes in FEV/FVC and RV/TLC with aging.

Multiple breath nitrogen washout (MBNW) indices provide insight into ventilation heterogeneity globally [lung clearance index (LCI)] and within acinar (S) and conducting (S) airways. Normal aging leads to an accelerated deterioration of S in older adults, but little is known about the contribution of peripheral airway function to changes in pulmonary function indices reflecting expiratory airflow [forced expiratory volume in one second (FEV)/forced vital capacity (FVC)] and gas trapping [residual volume (RV)/total lung capacity (TLC)] with aging. We aimed to examine associations between MBNW and FEV/FVC as well as RV/TLC in healthy adults, and to determine if these relationships differ in older (≥50 yr) versus younger subjects (<50 yr).

Measurement duration impacts variability but not impedance measured by the forced oscillation technique in healthy, asthma and COPD subjects.

The forced oscillation technique (FOT) is gaining clinical acceptance, facilitated by more commercial devices and clinical data. However, the effects of variations in testing protocols used in FOT data acquisition are unknown. We describe the effect of duration of data acquisition on FOT results in subjects with asthma, chronic obstructive pulmonary disease (COPD) and healthy controls.

Changes in oscillatory impedance and nitrogen washout with combination fluticasone/salmeterol therapy in COPD.

Introduction: Combination inhaled corticosteroid/long-acting bronchodilator (ICS/LABA) therapy reduces the exacerbation rate and improves spirometry and quality of life in COPD. We hypothesized that ICS/LABA therapy also improves small airway function measured by FOT.

Methods: 14 subjects with COPD were commenced on combination fluticasone propionate/salmeterol therapy for 3 months.

Day-to-day variability of oscillatory impedance and spirometry in asthma and COPD.

Variability in airway function may be a marker of disease activity in COPD and asthma. The aim was to determine the effects of repeatability and airway obstruction on day-to-day variability in respiratory system resistance (Rrs) and reactance (Xrs) measured by forced oscillation technique (FOT). Three groups of 10 subjects; normals, stable asthmatic and stable COPD subjects underwent daily FOT recordings for 7 days.

The relationship between airflow obstruction, emphysema extent, and small airways function in COPD.

Background: The severities of COPD (FEV(1) % predicted) and airflow obstruction (FEV(1)/FVC) are considered to be due to both emphysema and small airways disease. To our knowledge, this has not been previously confirmed by combined measurements of emphysema and of small airway function. We hypothesized that small airways disease and emphysema extent contribute independently to the severity of both COPD and airflow obstruction.