Document Detail

Rib cage mechanics during quiet breathing and exercise in humans.
MedLine Citation:
PMID:  9338434     Owner:  NLM     Status:  MEDLINE    
During exercise, large pleural, abdominal, and transdiaphragmatic pressure swings might produce substantial rib cage (RC) distortions. We used a three-compartment chest wall model (J. Appl. Physiol. 72: 1338-1347, 1992) to measure distortions of lung- and diaphragm-apposed RC compartments (RCp and RCa) along with pleural and abdominal pressures in five normal men. RCp and RCa volumes were calculated from three-dimensional locations of 86 markers on the chest wall, and the undistorted (relaxation) RC configuration was measured. Compliances of RCp and RCa measured during phrenic stimulation against a closed airway were 20 and 0%, respectively, of their values during relaxation. There was marked RC distortion. Thus nonuniform distribution of pressures distorts the RC and markedly stiffens it. However, during steady-state ergometer exercise at 0, 30, 50, and 70% of maximum workload, RC distortions were small because of a coordinated action of respiratory muscles, so that net pressures acting on RCp and RCa were nearly the same throughout the respiratory cycle. This maximizes RC compliance and minimizes the work of RC displacement. During quiet breathing, plots of RCa volume vs. abdominal pressure were to the right of the relaxation curve, indicating an expiratory action on RCa. We attribute this to passive stretching of abdominal muscles, which more than counterbalances the insertional component of transdiaphragmatic pressure.
C M Kenyon; S J Cala; S Yan; A Aliverti; G Scano; R Duranti; A Pedotti; P T Macklem
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  83     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1997 Oct 
Date Detail:
Created Date:  1997-11-26     Completed Date:  1997-11-26     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1242-55     Citation Subset:  IM    
Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada H2X 2P4.
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MeSH Terms
Abdomen / anatomy & histology,  physiology
Diaphragm / anatomy & histology,  physiology
Exercise / physiology*
Lung / anatomy & histology,  physiology
Lung Volume Measurements
Models, Anatomic
Muscle Relaxation / physiology
Respiratory Mechanics / physiology*
Ribs / anatomy & histology,  physiology*

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

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