Expiratory flow limitation relates to symptoms during COPD exacerbations requiring hospital admission.

Background: Expiratory flow limitation (EFL) is seen in some patients presenting with a COPD exacerbation; however, it is unclear how EFL relates to the clinical features of the exacerbation. We hypothesized that EFL when present contributes to symptoms and duration of recovery during a COPD exacerbation. Our aim was to compare changes in EFL with symptoms in subjects with and without flow-limited breathing admitted for a COPD exacerbation.

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.

The feasibility of home monitoring of impedance with the forced oscillation technique in chronic obstructive pulmonary disease subjects.

Respiratory system resistance (Rrs) and reactance (Xrs) measured by forced oscillation technique (FOT) can be potentially used for home monitoring in COPD. Our aims were to determine the technical acceptability, adherence and variability of unsupervised, home FOT measurements over ten consecutive days. Supervised spirometry and FOT measurements were made on ten clinically stable COPD subjects at their homes at the study initiation.

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.