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Techniques for measurement of thoracoabdominal asynchrony
G Kim Prisk1, J Hammer, Christopher J L Newth
1Division of Physiology, Department of Medicine, University of California at San Diego, La Jolla, California 92093-0931, USA. kprisk@ucsd.edu
Pediatric Pulmonology
|November 8, 2002
Summary
Respiratory motion analysis using Lissajous figures can be inaccurate. Cross-correlation and maximum linear correlation are superior methods for measuring thoraco-abdominal asynchrony (phase angle phi), even with noisy, non-sinusoidal breathing patterns.
Area of Science:
- Physiology
- Biomedical Engineering
- Respiratory Mechanics
Background:
- Respiratory inductance plethysmography is used to measure breathing patterns.
- Traditional Lissajous figure analysis assumes sinusoidal breathing, which is often inaccurate.
- Thoraco-abdominal asynchrony is quantified by phase angle phi, but its measurement is sensitive to waveform shape.
Purpose of the Study:
- To compare six time-domain methods for measuring phase angle phi.
- To evaluate the accuracy of these methods with simulated and animal data.
- To identify the most reliable method for assessing thoraco-abdominal asynchrony.
Main Methods:
- Simulated respiratory data with varying waveforms, phase shifts, and noise were generated.
- Six time-domain methods, including Lissajous figure analysis, cross-correlation, and maximum linear correlation, were applied.
- Data from anesthetized rhesus monkeys subjected to inspiratory resistive loading were analyzed.
Main Results:
- Cross-correlation and maximum linear correlation demonstrated the lowest errors (<5 degrees) with simulated data.
- Lissajous figure analysis showed significant errors (>30 degrees) in some cases.
- Both correlation methods yielded similar, reliable results in animal data, outperforming other techniques.
Conclusions:
- Phase angle phi measurement is best achieved using cross-correlation or maximum linear correlation.
- These correlation-based methods are robust to waveform shape variations and noise.
- Accurate measurement of thoraco-abdominal asynchrony is crucial for understanding respiratory mechanics.