Chapter 8
Occlusion Identification and Relief within Branched Structures


The technique of utilizing acoustic pressure-wave propagation response within a pipe system to identify changes in system properties has been utilized for diagnoses and therapy of the human respiratory system. In this chapter, a theoretical model based on a compliant tube with a constriction that can be applied to many practical applications is developed to diagnose occlusions within the cardiovascular and respiratory systems. The model is applied to study the dynamic response of a tube where both the elastance and inertance of the walls are considered and will focus on establishing an appropriate theoretical technique for identifying an obstruction in a flexible compliant tube system. On the basis of the single tube, two asymmetric branching network models are developed. Using the acoustic input impedance, the resonant frequency spectrum is used to interpret the characteristics of the airway system with the purpose of diagnosing diseases such as asthma. This is achieved by comparing the resonant frequency spectrum to that of a healthy respiratory system and enables the prediction of location and degree of obstruction within the respiratory system. This identification technique could also determine the characteristics of an airway pressure wave form that will lead to airway dilation and asthma relief.

  • Abstract
  • 8.1 The Structure of Respiratory System
  • 8.2 A Distributed Model for the Respiratory Airways
  • 8.8.1 Governing Equations
  • 8.2.2 Tube Wall Inertia
  • 8.2.3 Linearized Model
  • 8.2.4 Mathematical Model
  • 8.3. Acoustic Impedance Response of Respiratory System
  • 8.3.1. Uniform Model
  • 8.3.2. Gradual Model
  • 8.3.3. One-Generation Two-Branch Model
  • 8.3.4. Two-Generation Four-Branch Model
  • 8.4. Application of Acoustic Impedance Response in Diagnoses of Respiratory System and Other Clinical Uses
  • 8.4.1. Diagnoses of Respiratory System
  • 8.4.2. Monitoring Respiratory Impedance During Continuous Positive Airway Pressure
  • 8.4.3 Forced Oscillation Technique to Reflex Bronchodilation
  • References

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