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Design of an inductive plethysmograph for ventilation measurement
K P Cohen1, D Panescu, J H Booske
1Department of Electrical and Computer Engineering, University of Wisconsin-Madison 53706.
Physiological Measurement
|May 1, 1994
Summary
We developed a new inductive plethysmograph for non-invasive ventilation measurement. This device accurately detects breathing patterns and shows promise for identifying airway obstruction with fewer artifacts.
Area of Science:
- Biomedical Engineering
- Respiratory Physiology
Background:
- Non-invasive ventilation monitoring is crucial for respiratory diagnostics.
- Existing methods like impedance pneumography can be prone to artifacts.
Purpose of the Study:
- To design and evaluate an inductive plethysmograph for accurate, non-invasive ventilation measurement.
- To assess the device's capability in detecting normal breathing and simulated airway obstruction.
Main Methods:
- Utilized two elastic bands with insulated wires around the chest and abdomen to measure cross-sectional area changes via inductance.
- Employed Colpitts oscillators where inductive bands form tank circuit elements, measuring resonant frequency shifts.
- Conducted simulations to optimize oscillator frequencies and minimize magnetic coupling/frequency locking.
- Compared inductive plethysmography with impedance pneumography and spirometry for ventilation recordings.
Main Results:
- Inductive plethysmography provided ventilation measurements comparable to impedance pneumography and spirometry for normal breathing.
- The inductive device demonstrated reduced susceptibility to artifacts from pressure and movement compared to impedance pneumography.
- Simulated airway obstruction resulted in out-of-phase signals between chest and abdominal bands, indicating potential for obstruction detection.
Conclusions:
- The designed inductive plethysmograph offers a reliable non-invasive method for assessing ventilation.
- The technique shows potential for differentiating normal breathing from airway obstruction.
- Further development may enhance artifact reduction and diagnostic capabilities in respiratory monitoring.