High-frequency oscillations in human respiratory electromyograms during voluntary breathing

Area of Science:

• Respiratory Physiology
• Neuroscience
• Biomedical Engineering

Background:

• Respiratory muscle activity is crucial for breathing.
• Electromyography (EMG) is used to measure muscle electrical activity.
• High-frequency oscillations in neural and muscle signals are of research interest.

Purpose of the Study:

• To investigate high-frequency oscillations in human respiratory muscles during voluntary breathing.
• To determine if these oscillations are common between different respiratory muscles.
• To explore the utility of coherence spectrum analysis for detecting these oscillations.

Main Methods:

• EMGs were recorded from human subjects' rib cage and esophageal diaphragm during controlled breathing.
• Simultaneous EMG samples were collected during inspiration.
• Power spectra and squared coherence spectra were calculated for EMG signals.

Main Results:

• Common high-frequency oscillations (70-100 Hz and 20-50 Hz) were identified between rib cage and diaphragm EMGs using coherence spectrum analysis.
• These oscillations were present in both early and late inspiration.
• High-frequency oscillations were not consistently apparent in power spectra alone.
• ECG contamination significantly altered coherence spectra.

Conclusions:

• Coherence spectrum analysis is a sensitive method for detecting common high-frequency oscillations in respiratory muscle EMGs.
• These findings suggest a shared neural mechanism underlying these oscillations in respiratory muscles.
• Further research is needed to elucidate the precise mechanism and implications of these oscillations.