Abstract
The use of non-invasive methods for the study of respiratory
muscle signals can provide clinical information for the
evaluation of the respiratory muscle function. The aim of this
study was to evaluate the electrical activity of the
sternocleidomastoid muscle recorded superficially by means of
a concentric ring electrode (CRE) in bipolar configuration. This
sensor enhances the spatial resolution of the signal recorded,
attenuates interferences, as the cardiac activity, and also
simplifies the orientation problem associated to the electrode
location on the muscle under study. Five healthy subjects
underwent a respiratory load test in which an inspiratory load
was imposed during the inspiratory phase.
During the test, the electromyographic signal of the
sternocleidomastoid muscle (EMGsc) and the inspiratory mouth
pressure (Pmouth) were acquired. The EMGsc signal was
processed using the fixed sample entropy (fSampEn), a
technique for the amplitude estimation of signals that is robust
in presence of impulsive noise as cardiac activity. The
agreement between the Pmouth and the fSampEn over the
EMGsc signal showed a moderate Pearsons correlation value
at the lowest inspiratory load (0.46 ± 0.11) and a very strong
value at the highest inspiratory load (0.84 ± 0.08). In
conclusion, the surface recordings of the EMGsc signal using a
CRE and the estimation of its amplitude using the fSampEn
technique can be used for the study of muscle respiratory
activity.
