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

Kanika Jetmalani; Sophie Timmins; Nathan J Brown; Chantale Diba; Norbert Berend; Cheryl M Salome; Fu-Qiang Wen; Peng Chen; Gregory G King; Claude S Farah

doi:10.2147/COPD.S78332

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

Int J Chron Obstruct Pulmon Dis. 2015 May 14:10:939-45. doi: 10.2147/COPD.S78332. eCollection 2015.

Authors

Affiliations

¹ Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia ; Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
² Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia ; Department of Respiratory Medicine, Royal North Shore Hospital, Sydney, NSW, Australia ; Cooperative Research Centre for Asthma and Airways, George Institute of Global Health, Sydney, NSW, Australia.
³ Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia ; Cooperative Research Centre for Asthma and Airways, George Institute of Global Health, Sydney, NSW, Australia.
⁴ Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia ; Cooperative Research Centre for Asthma and Airways, George Institute of Global Health, Sydney, NSW, Australia ; Department of Respiratory Research, George Institute of Global Health, Sydney, NSW, Australia.
⁵ Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia ; Sydney Medical School, University of Sydney, Sydney, NSW, Australia ; Cooperative Research Centre for Asthma and Airways, George Institute of Global Health, Sydney, NSW, Australia.
⁶ Department of Medicine, West China Hospital, West China School of Medicine, Sichuan University, Chengdu, People's Republic of China.
⁷ Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia ; Sydney Medical School, University of Sydney, Sydney, NSW, Australia ; Department of Respiratory Medicine, Royal North Shore Hospital, Sydney, NSW, Australia ; Cooperative Research Centre for Asthma and Airways, George Institute of Global Health, Sydney, NSW, Australia.
⁸ Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia ; Sydney Medical School, University of Sydney, Sydney, NSW, Australia ; Department of Respiratory Medicine, Concord Hospital, Sydney, NSW, Australia.

Abstract

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.

Subjects and methods: A total of 29 subjects with COPD were recruited within 48 hours of admission to West China Hospital for an acute exacerbation. Daily measurements of post-bronchodilator spirometry, resistance, and reactance using the forced oscillation technique and symptom (Borg) scores until discharge were made. Flow-limited breathing was defined as the difference between inspiratory and expiratory respiratory system reactance (EFL index) greater than 2.8 cmH2O·s·L(-1). The physiological predictors of symptoms during recovery were determined by mixed-effect analysis.

Results: Nine subjects (31%) had flow-limited breathing on admission despite similar spirometry compared to subjects without flow-limited breathing. Spirometry and resistance measures did not change between enrolment and discharge. EFL index values improved in subjects with flow-limited breathing on admission, with resolution in four patients. In subjects with flow-limited breathing on admission, symptoms were related to inspiratory resistance and EFL index values. In subjects without flow-limited breathing, symptoms related to forced expiratory volume in 1 second/forced vital capacity. In the whole cohort, EFL index values at admission was related to duration of stay (Rs=0.4, P=0.03).

Conclusion: The presence of flow-limited breathing as well as abnormal respiratory system mechanics contribute independently to symptoms during COPD exacerbations.

Keywords: COPD; exacerbations; flow limitation; respiratory mechanics; symptoms.

Publication types

Comparative Study
Observational Study
Research Support, Non-U.S. Gov't

MeSH terms

Aged
Airway Resistance
Bronchodilator Agents / therapeutic use
China
Disease Progression
Exhalation* / drug effects
Female
Forced Expiratory Volume
Humans
Inhalation
Lung / drug effects
Lung / physiopathology*
Male
Middle Aged
Patient Admission*
Prospective Studies
Pulmonary Disease, Chronic Obstructive / complications
Pulmonary Disease, Chronic Obstructive / diagnosis
Pulmonary Disease, Chronic Obstructive / drug therapy
Pulmonary Disease, Chronic Obstructive / physiopathology*
Recovery of Function
Spirometry
Time Factors
Treatment Outcome
Vital Capacity

Substances

Bronchodilator Agents