Author:
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Torres Cebrián, Abel; Sarlabous Uranga, Leonardo; Fiz Fernández, José Antonio; Gea Guiral, Joaquim; Martínez Llorens, Juana María; Morera Prat, Josep Maria; Jané Campos, Raimon
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Abstract:
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The study of mechanomyographic (MMG) signals
of respiratory muscles is a promising noninvasive technique in
order to evaluate the respiratory muscular effort and
efficiency. In this work, the MMG signal of the diaphragm
muscle it is evaluated in order to assess the respiratory
muscular function in Chronic Obstructive Pulmonary Disease
(COPD) patients. The MMG signals from left and right
hemidiaphragm were acquired using two capacitive
accelerometers placed on both left and right sides of the costal
wall surface. The MMG signals and the inspiratory pressure
signal were acquired while the COPD patients carried out an
inspiratory load respiratory test. The population of study is
composed of a group of 6 patients with severe COPD
(FEV1>50% ref and DLCO<50% ref). We have found high
positive correlation coefficients between the maximum
inspiratory pressure (IPmax) developed in a respiratory cycle
and different amplitude parameters of both left and right
MMG signals (RMS, left: 0.68±0.11 – right: 0.69±0.12; Rényi
entropy, left: 0.73±0.10 – right: 0.77±0.08; Multistate Lempel-
Ziv, left: 0.73±0.17 – right: 0.74±0.08), and negative correlation
between the Pmax and the maximum frequency of the MMG
signal spectrum (left: -0.39±0.19 – right: -0.65±0.09).
Furthermore, we found that the slope of the evolution of the
MMG amplitude parameters, as the load increases during the
respiratory test, has positive correlation with the %FEV1/FVC
pulmonary function test parameter of the six COPD patients
analyzed (RMS, left: 0.38 – right: 0.41; Rényi entropy, left:
0.45 – right: 0.63; Multistate Lempel-Ziv, left: 0.39 – right:
0.64). These results suggest that the information provided by
MMG signals could be used in order to evaluate the respiratory
effort and the muscular efficiency in COPD patients. |