Document Detail

Partitioning of the elastic work of inspiration in patients with COPD during exercise.
MedLine Citation:
PMID:  9551747     Owner:  NLM     Status:  MEDLINE    
During exercise, dynamic hyperinflation-induced intrinsic positive end-expiratory pressure (PEEPi) and decreased dynamic lung compliance (CL,dyn) of patients with chronic obstructive pulmonary disease (COPD) increase the elastic work of inspiration (Wi) more than would be predicted from the increase in tidal volume (VT). This contributes significantly to their exertional breathlessness. In 10 stable patients with COPD, the dynamic Wi was measured during incremental bicycle exercise to exhaustion. The total Wi was then partitioned into the portion required to overcome PEEPi (Wi,PEEPi) and nonPEEPi elastic load (Wi,nonPEEPi). The latter is used to overcome the increase in the total respiratory system elastance during inflation. From resting breathing to peak exercise, Wi more than doubled (p<0.001). This increase was largely due to Wi,PEEPi, which significantly rose from 1.7+/-0.3 to 5.3+/-0.8 L x cm H2O(-1) (p<0.001). In comparison, Wi,nonPEEPi increased from only 3.0+/-0.4 to 5.1+/-0.5 L x cm H2O(-1) (p<0.01). Consequently, Wi,PEEPi as a fraction of total Wi increased from 35.5+/-5.6 to 51.0+/-3.3% (p<0.02). In addition, the measured Wi,nonPEEPi at peak exercise, when expressed as a percentage of its value during resting breathing, was 25% more than that predicted from the increase in VT alone. Assuming a constant chest wall compliance, this can be attributed to the exercise-induced decrease in CL,dyn, which was 0.27+/-0.04 and 0.17+/-0.02 L x cm H2O(-1) (p<0.01), respectively, during resting breathing and peak exercise. In conclusion, the dynamic hyperinflation-induced intrinsic positive end-expiratory pressure is more important than the increase in tidal volume in raising the work of inspiration during exercise in patients with chronic obstructive pulmonary disease; the decrease in dynamic lung compliance plays a definite but less important role.
P Sliwinski; D Kaminski; J Zielinski; S Yan
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The European respiratory journal     Volume:  11     ISSN:  0903-1936     ISO Abbreviation:  Eur. Respir. J.     Publication Date:  1998 Feb 
Date Detail:
Created Date:  1998-06-12     Completed Date:  1998-06-12     Revised Date:  2013-05-23    
Medline Journal Info:
Nlm Unique ID:  8803460     Medline TA:  Eur Respir J     Country:  DENMARK    
Other Details:
Languages:  eng     Pagination:  416-21     Citation Subset:  IM    
Institute of Tuberculosis and Lung Diseases, Warsaw, Poland.
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MeSH Terms
Lung Compliance
Lung Diseases, Obstructive / physiopathology*
Lung Volume Measurements
Middle Aged
Positive-Pressure Respiration
Tidal Volume
Work of Breathing*

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