Document Detail

Detection of expiratory flow limitation in COPD using the forced oscillation technique.
MedLine Citation:
PMID:  14979497     Owner:  NLM     Status:  MEDLINE    
Expiratory flow limitation (EFL) during tidal breathing is a major determinant of dynamic hyperinflation and exercise limitation in chronic obstructive pulmonary disease (COPD). Current methods of detecting this are either invasive or unsuited to following changes breath-by-breath. It was hypothesised that tidal flow limitation would substantially reduce the total respiratory system reactance (Xrs) during expiration, and that this reduction could be used to reliably detect if EFL was present. To test this, 5-Hz forced oscillations were applied at the mouth in seven healthy subjects and 15 COPD patients (mean +/- sD forced expiratory volume in one second was 36.8 +/- 11.5% predicted) during quiet breathing. COPD breaths were analysed (n=206) and classified as flow-limited if flow decreased as alveolar pressure increased, indeterminate if flow decreased at constant alveolar pressure, or nonflow-limited. Of these, 85 breaths were flow-limited, 80 were not and 41 were indeterminate. Among other indices, mean inspiratory minus mean expiratory Xrs (deltaXrs) and minimum expiratory Xrs (Xexp,min) identified flow-limited breaths with 100% specificity and sensitivity using a threshold between 2.53-3.12 cmH2O x s x L(-1) (deltaXrs) and -7.38- -6.76 cmH2O x s x L(-1) (Xexp,min) representing 6.0% and 3.9% of the total range of values respectively. No flow-limited breaths were seen in the normal subjects by either method. Within-breath respiratory system reactance provides an accurate, reliable and noninvasive technique to detect expiratory flow limitation in patients with chronic obstructive pulmonary disease.
R L Dellacà; P Santus; A Aliverti; N Stevenson; S Centanni; P T Macklem; A Pedotti; P M A Calverley
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The European respiratory journal     Volume:  23     ISSN:  0903-1936     ISO Abbreviation:  Eur. Respir. J.     Publication Date:  2004 Feb 
Date Detail:
Created Date:  2004-02-24     Completed Date:  2004-08-26     Revised Date:  2013-05-23    
Medline Journal Info:
Nlm Unique ID:  8803460     Medline TA:  Eur Respir J     Country:  Denmark    
Other Details:
Languages:  eng     Pagination:  232-40     Citation Subset:  IM    
TBMLab, Dipartimento di Bioingegneria, Politecnico di Milano University, Milan, Italy.
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MeSH Terms
Air Pressure
Airway Resistance / physiology
Exhalation / physiology
Forced Expiratory Flow Rates / physiology*
Lung Volume Measurements
Middle Aged
Oscillometry / methods*
Pulmonary Alveoli / physiopathology
Pulmonary Disease, Chronic Obstructive / diagnosis*,  physiopathology
Reference Values
Respiratory Mechanics / physiology
Comment In:
Eur Respir J. 2004 Feb;23(2):187-8   [PMID:  14979488 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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