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Volume quantification of chest wall motion in dogs
S Krayer1, M Decramer, J Vettermann
1Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota 55905.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 1, 1988
Summary
The diaphragm primarily drives lung inflation, contributing 62% to tidal volume, while rib cage motion contributes 40%. Diaphragmatic contraction does not expand the rib cage during breathing in supine dogs.
Area of Science:
- Physiology
- Respiratory Mechanics
Background:
- Understanding the relative contributions of the diaphragm and rib cage to breathing is crucial for respiratory physiology.
- Previous studies have explored respiratory muscle function, but precise volume contributions during spontaneous breathing require further elucidation.
Purpose of the Study:
- To quantify the volume contributions of rib cage (delta Vrc) and diaphragmatic motion (delta Vdi) to tidal volume (VT) during spontaneous breathing.
- To investigate the mechanical interactions between the diaphragm and rib cage during inspiration.
Main Methods:
- High-speed multisliced X-ray computed tomography was used to measure volume changes in 6 anesthetized supine dogs.
- Respiratory maneuvers included spontaneous breathing, phrenic nerve stimulation, and breathing after phrenicotomy.
Main Results:
- Diaphragmatic motion accounted for 62% of tidal volume, while rib cage motion contributed 40%.
- Diaphragmatic contraction did not significantly expand the rib cage above the zone of apposition.
- Relaxation of expiratory muscles contributed to both rib cage and diaphragmatic motion during inspiration.
Conclusions:
- The diaphragm is the primary driver of lung inflation, not the rib cage, during spontaneous breathing in this model.
- Rib cage motion does not significantly influence diaphragmatic position during spontaneous breathing in anesthetized supine dogs.