Diaphragmatic electromyogram power-spectral analysis as a function of reduced end-expiratory lung volume

Area of Science:

• Physiology
• Respiratory Mechanics
• Electromyography

Background:

• The electromyogram (EMG) power spectrum provides insights into muscle function.
• Understanding diaphragm muscle activity is crucial for respiratory physiology.

Purpose of the Study:

• To investigate the impact of altered lung volumes on the electromyogram power-frequency spectra of the costal and crural diaphragms.
• To determine if changes in end-expiratory lung volume (EELV) affect diaphragm EMG centroid frequency (Fc).

Main Methods:

• Electromyogram (EMG) signals from costal (EMGco) and crural (EMGcr) diaphragms were recorded in anesthetized piglets.
• Abdominal banding was used to reduce end-expiratory lung volume (EELV).
• Fast Fourier transformation computed power-frequency spectra and centroid frequency (Fc) from ECG-free EMG signals.

Main Results:

• Abdominal banding reduced EELV by an average of 30.6% from functional residual capacity.
• The mean Fc of the EMGcr was not significantly altered by reduced EELV.
• The mean Fc of the EMGco decreased by 13% in all animals at reduced EELV (p < 0.05).

Conclusions:

• Lung volume alterations alone can change the EMG power spectrum and Fc of the costal diaphragm.
• Interpreting costal diaphragm EMG power spectral analysis requires consideration of end-expiratory lung volume status.