Diaphragm mechanics in dogs with unilateral emphysema

Rolf D. Hubmayr, Gaspar A. Farkas, Hung Yang Tao, Gary C. Sieck, Susan S. Margulies

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

We studied dogs with unilateral papain-induced emphysema to answer two questions: (1) Do emphysema lung-apposed hemidiaphragm (DiE) and normal lung-apposed hemidiaphragm (DiN) have equal capacities for lowering lung surface pressure? and (2) Are side-to-side differences in intrathoracic pressure the result of unequal force outputs by DiE and DiN or are they caused by differences in their mechanical efficiency as pressure generators? After the airways of the emphysematous and normal lungs were intubated with a dual lumen endotracheal tube, both phrenic nerves were maximally stimulated at rates between 1 and 50 Hz and the changes in airway occlusion pressure (ΔPaoE,N) and diaphragm length (sonomicrometry) were recorded. In all animals, ΔPaoN exceeded ΔPaoE. Differences in pressure ranged from 1.2±0.6 cm H2O during a twitch to 6.0±2.9 cm H2O during a 50-Hz tetanus. Midcostal bundles of DiE shortened less than corresponding bundles of DiN, but both reached the same active length relative to their optimal lengths, which were measured in vitro. There was no significant difference in fiber type distribution, fiber cross-sectional area, or maximal isometric tetanic tensions among midcostal regions of DiE and DiN. We conclude that unilateral hyperinflation impairs the mechanical efficiency of the apposing hemidiaphragm as a pressure generator.

Original languageEnglish (US)
Pages (from-to)1598-1603
Number of pages6
JournalJournal of Clinical Investigation
Volume91
Issue number4
DOIs
StatePublished - Apr 1993

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Keywords

  • Chest wall mechanics
  • Regional ventilation
  • Single lung transplantation
  • Unilateral hyperinflation

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Hubmayr, R. D., Farkas, G. A., Tao, H. Y., Sieck, G. C., & Margulies, S. S. (1993). Diaphragm mechanics in dogs with unilateral emphysema. Journal of Clinical Investigation, 91(4), 1598-1603. https://doi.org/10.1172/JCI116366