Document Detail

Mechanics of the canine diaphragm in pleural effusion.
MedLine Citation:
PMID:  22797306     Owner:  NLM     Status:  MEDLINE    
Pleural effusion is a complicating feature of many diseases of the lung and pleura, but its effects on the mechanics of the diaphragm have not been assessed. In the present study, radiopaque markers were attached along muscle bundles in the midcostal region of the diaphragm in anesthetized dogs, and the three-dimensional location of the markers during relaxation before and after the stepwise introduction of liquid into the left or right pleural space and during phrenic nerve stimulation in the same conditions was determined using computed tomography. From these data, accurate measurements of diaphragm muscle length and displacement were obtained, and the changes in pleural and abdominal pressure were analyzed as functions of these parameters. The effect of liquid instillation on the axial position of rib 5 was also measured. The data showed that 1) liquid leaked through the dorsal mediastinal sheet behind the pericardium so that effusion was bilateral; 2) effusion caused a caudal displacement of the relaxed diaphragm; 3) this displacement was, compared with passive lung inflation, much larger than the cranial displacement of the ribs; and 4) the capacity of the diaphragm to generate pressure, in particular pleural pressure, decreased markedly as effusion increased, and this decrease was well explained by the decrease in active muscle length. It is concluded that pleural effusion has a major adverse effect on the pressure-generating capacity of the diaphragm and that this is the result of the action of hydrostatic forces on the muscle.
André De Troyer; Dimitri Leduc; Matteo Cappello; Pierre Alain Gevenois
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-07-12
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  113     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-09-03     Completed Date:  2013-07-08     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:  785-90     Citation Subset:  IM    
Laboratory of Cardiorespiratory Physiology, Brussels School of Medicine, Brussels, Belgium.
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MeSH Terms
Diaphragm / innervation,  physiology*
Lung Volume Measurements / methods
Muscle Contraction / physiology
Phrenic Nerve / physiology
Pleural Effusion / physiopathology*
Respiratory Mechanics / physiology*

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