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Clinical characteristics of COPD patients with tidal expiratory flow limitation

Year: 2017
Type: conference-abstract
Abstract: Background: Small airway disease is a recognised feature of COPD. Small airway narrowing may cause gas-trapping on expiration. Small airway closure during expiration can prevent low frequency oscillometric signals from reaching the distal lung. These are called “choke points” in the airways that are present during expiration but not inspiration, causing a marked change in measured compliance during a breathing cycle. This is referred to as expiratory flow limitation (EFL). The difference between inspiratory and expiratory reactance at 5 Hz (∆X5) can identify EFL during tidal breathing in COPD patients. Aims: To determine the clinical characteristics of COPD patients with EFL. Methods: 147 COPD patients were assessed; 75 were part of COPD MAP consortium. Health questionnaires, impulse oscillometry, plethysmography, KCO, spirometry and 6 minute walk distance (6MWD) were assessed. EFL was defined as ∆X5≥0.28 kPa/L/s. Results: 55 patients (37.4%) had EFL. Patients with EFL were more likely to be current smokers (p=0.01) with worse airflow obstruction (mean: 42 v 59% predicted FEV1; p<0.0001) and more gas trapping (RV medians: 166 v 121% predicted; p<0.0001). The EFL group had worse SGRQ activity and symptom component scores, lower 6 minute walk distances (mean: 343 v 393 metres; p=0.002), and greater peripheral airway resistance (R5-R20 means: 0.41 v 0.15 kPa/L/s; p<0.0001). Patients with EFL had comparable KCO to other COPD patients. Conclusion: Approximately a third of COPD patients have EFL at rest; this subgroup exhibits multiple clinical characteristics of more severe disease.
DOI: 10.1183/1393003.congress-2017.pa2229
Language: English
Field: Medicine
Open Access status: green
OpenAlex ID: W2776069098
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Cited by: 1
Related to: 10