Instantaneous phase difference analysis between thoracic and abdominal movement signals based on complementary...

Area of Science:

• Respiratory Physiology
• Biomedical Signal Processing
• Medical Diagnostics

Background:

• Thoracoabdominal asynchrony is crucial for diagnosing respiratory diseases.
• Conventional Lissajous figure analysis has limitations including low temporal resolution and increased error with non-sinusoidal signals.
• Existing time-domain methods often require calibration to eliminate phase delay.

Purpose of the Study:

• To develop and validate a novel method for estimating the instantaneous phase difference in thoracoabdominal asynchrony.
• To overcome the limitations of conventional methods in terms of temporal resolution and signal non-sinusoidality.

Main Methods:

• Proposed a novel instantaneous phase difference method utilizing complementary ensemble empirical mode decomposition.
• Estimated the instantaneous phase relation between thoracic and abdominal wall movements.
• Validated the method using simulated time series and human-subject respiratory data (thoracic and abdominal breathing).
• Compared performance against Lissajous figure analysis and an automatic phase estimation procedure.

Main Results:

• The proposed method demonstrated lower standard deviations compared to conventional methods in simulations.
• The novel method exhibited higher accuracy in simulations.
• Results from human-subject data correlated positively with conventional methods and aligned with existing literature.
• The proposed method achieved the smallest standard deviation across all tested data.

Conclusions:

• The novel instantaneous phase difference method is effective for evaluating thoracoabdominal asynchrony.
• Advantages include improved temporal resolution, no phase delay, suitability for non-sinusoidal signals, and calibration-free operation.
• The method provides a more accurate and reliable assessment of respiratory mechanics.