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Regional chest wall impedance during nonrespiratory maneuvers
G M Barnas1, P J Mills, C F MacKenzie
1Department of Anesthesiology, University of Maryland, Baltimore 21201.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|January 1, 1991
Summary
Chest wall properties change with nonrespiratory maneuvers. Muscle effort increases chest wall impedance, affecting rib cage and abdominal regions differently based on the specific maneuver.
Area of Science:
- Respiratory Mechanics
- Biomechanics
- Physiology
Background:
- Understanding chest wall mechanics is crucial for respiratory diagnostics.
- Nonrespiratory maneuvers can alter chest wall properties, impacting breathing.
- Limited data exists on regional chest wall impedance changes during static tasks.
Purpose of the Study:
- To evaluate alterations in total and regional chest wall properties during nonrespiratory maneuvers.
- To investigate the impact of muscle effort on chest wall impedance.
- To correlate impedance changes with electromyographic activity.
Main Methods:
- Six subjects performed static tasks at functional residual capacity.
- Quasi-sinusoidal forcing at the mouth was applied without active breathing.
- Measurements included electromyography, esophageal pressure, and rib cage/abdominal displacements.
Main Results:
- Total chest wall impedance (Zw) magnitude increased with effort during all maneuvers.
- Rib cage impedance (Zrc) and diaphragm-abdomen impedance (Zd-a) were affected differently by various maneuvers.
- Active trunk muscle engagement significantly increased regional impedances (>100%).
- Increases in regional impedance correlated with increased electromyographic activity.
Conclusions:
- Nonrespiratory maneuvers significantly alter chest wall mechanical properties.
- Muscle activation and postural changes modify regional chest wall impedances.
- These findings have implications for understanding respiratory system behavior under various conditions.