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Alternative model of respiratory tissue viscoplasticity
D Stamenović1, K R Lutchen, G M Barnas
1Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|September 1, 1993
Summary
A new model explains respiratory tissue impedance by coupling viscoelastic and plastoelastic components. This simplified, four-parameter model better describes chest wall and lung tissue behavior than previous theories.
Area of Science:
- Physiology
- Biophysics
- Respiratory Mechanics
Background:
- Respiratory tissue impedance shows dependencies on tidal volume and frequency during normal breathing.
- Hildebrandt's model, proposing parallel viscoelastic and plastoelastic compartments, qualitatively matched tissue behavior but had quantitative limitations and many parameters.
Purpose of the Study:
- To develop a new mechanical model for respiratory tissue impedance.
- To improve quantitative accuracy and reduce model complexity compared to existing models.
Main Methods:
- A novel model was proposed with serially coupled viscoelastic and plastoelastic compartments.
- The model, featuring four parameters, was fitted to in vivo impedance data from chest wall, healthy lungs, and edematous lungs using a least squares technique.
Main Results:
- The new model successfully explained major and subtle features of chest wall impedance data with fewer parameters and assumptions than Hildebrandt's model.
- The model suggests actin-myosin cross-bridge kinetics may underlie chest wall behavior and appears applicable to lung tissue.
Conclusions:
- A serially coupled model offers a more accurate and parsimonious explanation for respiratory tissue impedance, particularly for the chest wall.
- While applicable to lung tissue, the model's fit for edematous lungs requires further investigation.