Movement artefact rejection in impedance pneumography using six strategically placed electrodes

Area of Science:

• Biomedical Engineering
• Physiological Monitoring
• Signal Processing

Background:

• Impedance pneumography is a non-invasive method for respiratory monitoring.
• Movement artifacts significantly degrade the quality of impedance pneumography signals.
• Existing methods struggle to effectively differentiate between respiratory and motion-induced impedance changes.

Purpose of the Study:

• To develop and validate a novel technique for reducing movement artifacts in impedance pneumography.
• To investigate the effect of electrode placement and signal processing on artifact reduction.
• To improve the accuracy and reliability of respiratory monitoring using impedance pneumography.

Main Methods:

• A six-electrode configuration was designed based on the observation of electrode slippage during movement.
• A volume conductor model of the thoracic cavity was used to simulate movement artifacts.
• Symmetrical electrode pairs were analyzed, exploiting the phase relationship between breathing and movement signals.
• Averaging technique was applied to measurements from symmetrical pairs to cancel movement artifacts.

Main Results:

• Simulations showed impedance changes due to movement were 180 degrees out of phase in symmetrical pairs.
• Breathing-induced impedance changes were in phase in symmetrical pairs.
• Experimental data from human subjects confirmed the simulation findings.
• The proposed averaging method effectively reduced movement artifacts while preserving breathing signals.

Conclusions:

• Movement artifacts in impedance pneumography are primarily caused by electrode slippage.
• The proposed six-electrode configuration and averaging technique effectively mitigate movement artifacts.
• This method enhances the reliability of impedance pneumography for respiratory monitoring in dynamic conditions.