Document Detail

Inspiratory muscle mechanics of patients with chronic obstructive pulmonary disease during incremental exercise.
MedLine Citation:
PMID:  9309997     Owner:  NLM     Status:  MEDLINE    
Inspiratory muscles are weak and contribute to exercise limitation in chronic obstructive pulmonary disease (COPD). Differential inspiratory pressure contributions from the diaphragm and inspiratory rib cage muscles (RCMs) during exercise in patients with COPD patients are insufficiently described. We measured, in 16 patients with COPD, the global inspiratory muscle pressure (delta Pmus) and transdiaphragmatic pressure (delta Pdi) during an incremental bicycle exercise to exhaustion. The pressures needed to overcome the elastic load were further partitioned into portions for overcoming the PEEPi-imposed inspiratory threshold load (before the beginning of inspiratory flow) and for inflating the respiratory system (between the beginning and end of inspiratory flow). The delta Pdi/delta Pmus ratio was used to quantify the pressure contribution from RCMs relative to that from the diaphragm for a given inspiratory effort. We observed that in patients with COPD during exercise (1) there is a progressive increase in total inspiratory pressure contribution from RCMs relative to that of the diaphragm, and the magnitude of this increase appears to depend on the RCMs reserves during resting breathing; (2) most of the diaphragmatic pressure contribution occurs before the beginning of inspiratory flow, to overcome the PEEPi-imposed inspiratory threshold load; (3) RCMs pressure contribution predominates during the period of inspiratory flow once PEEPi is neutralized, not only for overcoming the elastic load caused by increased tidal volume, but also for compensating for the diaphragmatic pressure contribution during this interval that was gradually lost with increasing exercise work load.
S Yan; D Kaminski; P Sliwinski
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  156     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1997 Sep 
Date Detail:
Created Date:  1997-10-28     Completed Date:  1997-10-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  807-13     Citation Subset:  AIM; IM    
Montreal Chest Institute, Royal Victoria Hospital, Meakins-Christie Laboratories, McGill University, Quebec, Canada.
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MeSH Terms
Exercise Test / methods*
Inspiratory Capacity*
Lung Diseases, Obstructive / complications,  physiopathology*
Middle Aged
Positive-Pressure Respiration, Intrinsic / etiology
Respiratory Mechanics*
Respiratory Muscles / physiopathology*
Tidal Volume

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

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