Evaluation of vibromyographic signals from sternomastoid muscle in COPD patients during respiratory load tests

Analysis of the sternomastoid muscle activity in respiration can be a new non-invasive tool to assess the significance of chronic obstructive pulmonary disease (COPD). The aim of this work is the evaluation of vibromyographic (VMG) signals from the sternomastoid muscle, in order to study the muscle function in a ventilatory test. Simultaneous electromyographic (EMG) signals were recorded and a comparative analysis with VMG was done. Results from a group of 6 patients with COPD are shown, following two respiratory tests. The root-mean-square (RMS) showed the same behaviour of VMG and EMG signals in both tests. H/L ratios of power spectral density pointed out muscle fatigue in the last steps of the respiratory test. Cross-correlation of EMG and VMG found different patterns of relationship between the electrical and mechanical activity of muscle and allow the study of EMG-VMG time delay, during execution of respiratory load tests.