TY - JOUR
AU - Diba C.
AU - Berend N.
AU - King G.
AU - Timmins S.
AU - Salome C.
AU - Brown N.
AU - Farah C.
AU - Jetmalani K.
AU - Wen F.
AU - Chen P.
AB - <p>
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.
</p>

AD - Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia ; Sydney Medical School, University of Sydney, Sydney, NSW, Australia.<br/>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.<br/>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.<br/>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.<br/>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.<br/>Department of Medicine, West China Hospital, West China School of Medicine, Sichuan University, Chengdu, People's Republic of China.<br/>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.<br/>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.
AN - 25999709
BT - International Journal of Chronic Obstructive Pulmonary Disease
C2 - PMC4437522
DP - NLM
ET - 2015/05/23
LA - eng
LB - RSP
N1 - Jetmalani, Kanika<br/>Timmins, Sophie<br/>Brown, Nathan J<br/>Diba, Chantale<br/>Berend, Norbert<br/>Salome, Cheryl M<br/>Wen, Fu-Qiang<br/>Chen, Peng<br/>King, Gregory G<br/>Farah, Claude S<br/>Research Support, Non-U.S. Gov't<br/>New Zealand<br/>Int J Chron Obstruct Pulmon Dis. 2015 May 14;10:939-45. doi: 10.2147/COPD.S78332. eCollection 2015.
N2 - <p>
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.
</p>

PY - 2015
SN - 1178-2005 (Electronic)<br/>1176-9106 (Linking)
SP - 939
EP - 45
T2 - International Journal of Chronic Obstructive Pulmonary Disease
TI - Expiratory flow limitation relates to symptoms during COPD exacerbations requiring hospital admission
VL - 10
ER -