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Analysis of human chest wall motion using a two-compartment rib cage model
M E Ward1, J W Ward, P T Macklem
1Meakins-Christie Laboratories, McGill University Clinic, Royal Victoria Hospital, Montreal, Quebec, Canada.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1992
Summary
This study models human chest wall mechanics, revealing significant rib cage resistance to distortion. Rib cage muscles and this resistance are crucial for pressure changes during breathing.
Area of Science:
- Respiratory Physiology
- Biomechanics
- Thoracic Mechanics
Background:
- Previous models of chest wall mechanics by Macklem et al. provide a foundation.
- Understanding rib cage mechanics is vital for respiratory function.
- A two-compartment model of the rib cage is proposed for enhanced analysis.
Purpose of the Study:
- To extend existing chest wall models with a two-compartment rib cage.
- To quantify rib cage distortability and mechanical coupling.
- To determine the contribution of rib cage muscles to inspiratory pressure and the insertional component of transdiaphragmatic pressure.
Main Methods:
- Developed a two-compartment rib cage model (RCpul and RCab).
- Defined and measured rib cage distortability and mechanical coupling (Plink) using transcutaneous phrenic nerve stimulation.
- Calculated rib cage muscle pressure (Prcm) and the insertional component of transdiaphragmatic pressure (Pdi).
Main Results:
- Rib cage distortability and mechanical coupling were quantified.
- Prcm and Plink were found to be approximately equal during quiet breathing.
- The insertional component of Pdi was approximately 40% of total Pdi.
Conclusions:
- The human rib cage exhibits substantial resistance to distortion.
- Rib cage muscles and this resistance significantly influence pleural pressure changes.
- The model provides new insights into the mechanics of spontaneous inspiration.