Study of myographic signals from sternomastoid muscle inpatients with chronic obstructive pulmonary disease

Analysis of the respiratory muscle activity is a promising technique for di agnosis of respiratory diseases, such as chronic obstructive pulmonary dise ase (COPD), The sternomastoid muscle (SMM) was selected to study the activi ty of respiratory muscles due to its accessibility in order to define a non invasive analysis. The aims of this work are two: analyze the relationship between the SMM function and pulmonary obstruction, and study the influence of spectral estimator on frequency parameters related with the muscle acti vity. For the first goal, we propose the analysis of vibromyographic and el ectromyographic signals from the SMM to study the muscle function during tw o ventilatory tests. Activity of SMM was found by means of several indexes: root-mean-square (rms) values, mean and median frequencies, and ratio betw een high and low-frequency components. For the second goal, spectral analys is was performed by means of nonparametric methods: Correlogram and Welch p eriodogram, and parametric methods: autoregressive (AR), moving average (MA ), and ARMA models. IL is deduced that these indexes show muscle activity a nd certain fatigue of the SMM, whose muscle function depends on the level o f pulmonary obstruction, and they depend a lot of spectral estimator being the more suitable an AR model with high order.