Chest wall motion during epidural anesthesia in dogs

D. O. Warner, J. F. Brichant, E. L. Ritman, K. Rehder

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


To determine the relative contribution of rib cage and abdominal muscles to expiratory muscle activity during quiet breathing, we used lumbar epidural anesthesia in six pentobarbital sodium-anesthetized dogs lying supine to paralyze the abdominal muscles while leaving rib cage muscle motor function substantially intact. A high-speed X-ray scanner (Dynamic Spatial Reconstructor) provided three-dimensional images of the thorax. The contribution of expiratory muscle activity to tidal breathing was assessed by a comparison of chest wall configuration during relaxed apnea with that at end expiration. We found that expiratory muscle activity was responsible for approximately half of the changes in thoracic volume during inspiration. Paralysis of the abdominal muscles had little effect on the pattern of breathing, including the contribution of expiratory muscle activity to tidal breathing, in most dogs. We conclude that, although there is consistent phasic expiratory electrical activity in both the rib cage and the abdominal muscles of pentobarbital-anesthetized dogs lying supine, the muscles of the rib cage are mechanically the most important expiratory muscles during quiet breathing.

Original languageEnglish (US)
Pages (from-to)539-547
Number of pages9
JournalJournal of applied physiology
Issue number2
StatePublished - 1991


  • Dynamic Spatial Reconstructor
  • diaphragm
  • etidocaine
  • expiratory muscles
  • functional residual capacity
  • local anesthetics
  • rib cage
  • thoracic blood volume

ASJC Scopus subject areas

  • General Medicine


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