Mechanomyography as a Non-Invasive Technique for Diaphragm and Chest Wall Muscle Assessment in COPD Patients

This article discusses the use of mechanomyography as a non-invasive technique for diaphragm and chest wall muscle assessment in COPD patients. It explores the relationship between diaphragm and wall mechanomyography and EMG muscle signals in COPD patients. The article also covers the causes, diagnosis, prevention, and treatment of COPD. The experiments and results of the study are also discussed in detail.

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CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD)
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Introduction
Chronic obstructive pulmonary disease (COPD) is a lung obstructive disease that is
branded by long-standing breathing difficulties and poor respiratory functions. The patient
experiences difficulties in breathing, a productive cough and shortness of breath (Brij, Chatterji
& Marquette, 2016 p245). The disease is a progressive condition hence the symptoms worsen
with time. Therefore, the daily activities become difficult such as dressing, walking, and other
simple tasks. There are various causes of COPD that include genetics, tobacco smoking, and
pollution. However, the most common cause of this disease is the smoking of tobacco while the
other factors play a smaller role. Air pollution that causes this condition is due to poorly
ventilated heating and also cooking fires that have not undergone complete combustion (Brij,
Chatterji & Marquette, 2016 p250). The long-term exposure to these agents leads to the
development of an inflammatory response in the respiratory systems, especially in the lungs. The
airways become smaller and narrower while the lung tissues are destroyed. Diagnosis of COPD
is based on the determination of inefficient air flow measured by tests on lung functions.
Prevention is done by improving the outdoor and indoor air quality. Treatment is through
stopping smoking, lung transplant and rehabilitating the respiratory system. COPD is treated
using bronchodilators, steroids and oxygen therapy and there is also a vaccination that is given to
prevent this condition (Amal et al. 2017 p250).
Literature Review
In this article I will do a literature review for the patients that have COPD and the
relationship that exists between diaphragm and wall mechanomyography (MMG), EMG muscle
signals in patients that have COPD while comparing it with the lung functions of healthy
subjects and the identification of the muscles which will be affected by COPD during quiet

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breathing due to the severity of COPD (Chlif et al. 2016 p228). Mechanomyography has been
applied for detecting signals in the respiratory system to quantify the diaphragm muscle and the
coastal wall muscles functions and performance. This mechanism has been favored since it is
efficient and its intrinsic mechanical nature and the ability to assess muscle activity and function
non-invasively and at the same time preserving the muscular neuropathologic information. MMG
is used together with electromyogram (EMG) to determine diaphragmatic muscle efficiency and
respiratory power in patients with COPD (Sarlabous et al. 2017 p434).
Respiratory muscle dysfunction is the major problem that is experienced by patients with
chronic obstreperous respiratory conditions and has been connected to the pulmonic
hyperinflation (Sarlabous et al. 2017 p434). This condition is associated with diaphragm
shortening and other harmful changes that occur in the muscle force-size relationship hence
leading to reduced muscle ability to generate pressure hence they have a mechanical
disadvantage. Inspiratory muscle mechanical efficiency and strength may be reduced in patients
with this condition (Sarlabous et al. 2017 p434). However, at isovolume, the contracting force of
the diaphragmatic muscle in patients with COPD may be conserved or even enhanced in some
few instances. By the use of the MMG, the ratio between the electrical diaphragm activity and
the trans-diaphragmatic pressure can be used to measure the efficiency of the respirational
muscles which include the diaphragm muscle and the intercostal muscles which aid in respiration
during the periods of quiet breathing.
The gold standards in the assessment of diaphragm contractility in patients with
respirational illnesses such as chronic obstructive pulmonic disease involve the invasive
measures of the trans-diaphragmatic pressure. The surface MMG is a non-invasive method used
to assesses muscle fiber vibration during contraction. There is a great correlation between

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inspiratory mouth pressure which is taken to be a measure of respiratory muscle function and
diaphragm amplitude (Sarlabous et al. 2009 p3927). The MMG assesses the mechanical
activation of the diaphragm which is one of the inhalational muscles and the muscles of the
inferior rib cage wall in patients with COPD and also in healthy people to determine the
relationship that is present between the pulmonary function parameters and the inspiratory
muscle activation (Ottenheijm, Heunks & Dekhuijzen, 2008 p12).
Experiments
A propose System
The researches were carried out on the mechanomyography (MMG) which is a
noninvasive technique used to detect the effects of COPD on various respiratory muscles. COPD
has an adverse effect on the respiratory muscular efficiency and effort. The experiments will
involve the measurement of the lung muscle function by use of the MMG. The experiments
involve patients with COPD and healthy subjects used as control. Then results for all the
experiments will be recorded and discussed.
Procedures
The MMG involves the measurement of inspiratory pressure and the activities of the
diaphragm and the chest wall muscles in those with a pulmonic problem and in well subjects to
determine muscle activation and pulmonary function limitations (Ottenheijm, Heunks &
Dekhuijzen, 2008 p14). During the contraction periods, respiratory muscle fibers usually vibrate
laterally and these sensations are linked to the mechanical initiation of respirational muscles and
can be documented noninvasively. These parameters were then simultaneously recorded under
two different respiratory conditions, quiet breathing and increased ventilatory efforts. In one of

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the experiments carried out, the MMG signal of the diaphragm was assessed so as to determine
the respiratory muscular function in COPD patients. The MMG signals from both right and left
parts of the diaphragm muscle were recorded using the two accelerometers that were placed on
both sides of the coastal wall surface. The respiratory pressure indications and MMG signals
were recorded while these COPD patients carried out the inspiratory capacity respiratory tests.
These procedures were also repeated on healthy individuals who were set to be the control
subjects (Macintyre, 2006 p850).
Results Of The Experiments
The results showed that the COPD patients had a severe condition hence showed
abnormally high positive correlation coefficients that were obtained from the maximum
inspiratory pressure (Pmax) that was developed during the respiratory cycle. There were
different limitations to the amplitude of the left and right MMG signals. (RMS, on the right side:
0.69±0.12, and on the left: 0.68±0.11; Rényi entropy of the right: 0.77±0.08 and left side:
0.73±0.10; Multistate Lempel- Ziv, left: 0.73±0.17 while on the right hemidiaphragm:
0.74±0.08). These patients, therefore, showed a negative association between the highest MMG
frequency signal spectrum and the Pmax. These results from the MMG consequently was used to
evaluate the diaphragm muscle efficiency and the respiratory efforts in the patient with COPD.
COPD patients have reduced diaphragmatic muscle efficiency as well as decreased respiratory
power hence they have to put more efforts in the respiratory process. To validate the relationship
between Pmax and the MMG, this technique was done on the healthy individuals. There was a
close relationship between MMG and Pmax in the healthy subjects. During a forced respiratory
threshold loading protocol, the results were recorded and analyzed by the use of fixed sample
entropy (Motamedi-Fakhr, Wilson & Iles, 2017 p8).

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Discussion
From the above studies, it is clear that the MMG is an important, non-invasive indicator
of diaphragm and chest wall muscle functions of experimental and clinical significance used in
patients with COPD. This is done through the exploration of frequency and amplitude of the
signal of these muscles especially during muscle contractions for the optimal application. The
signals that are obtained with the MMG in patients with respiratory conditions is a feasible
complementary substitute to the conservative muscle assessment tools such as the EMG (Torres,
Galdiz, Gea, Morera & Jane, 2006 p5735). This technique also generates mechanical information
about the physiological facets of diaphragm and chest wall muscular activities hence help in
therapy such as exercises (Chlif et al. 2016 p228).
The Mechanical Of The Respiratory System And Diaphragm Muscle Assessment
Function
To determine the function ability of the respiratory system and the diaphragm muscle,
both the diaphragm and the intercostal muscle function should be evaluated. During the
breathing activity, these two organs contract hence expanding the chest cavity. The diaphragm
should become flat and move downwards while the intercostal muscles are expected to move the
ribcage upwards and outwards. Therefore, due to these changes in size, the internal pressure
decreases hence air from the outside which has a higher pressure than that of inside the thorax
rushes into the lungs to ensure that the pressures are at equilibrium (Crisafulli, Costi, Fabbri &
Clini, 2007 p20). In patients with COPD, the functions of the diaphragm and chest wall are
decreased since the diaphragm muscles and the chest wall contractility in individuals with COPD
is reduced. These patients also have reduced diaphragmatic mobility and reduced functions of the
chest wall hence this is the basis of the mechanism of action of the disease.

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Conclusion
The literature review and the experiments done above shows that the patients with
reduced respiratory abilities due to COPD have reduced diaphragmatic mobility and reduced
functions of the chest wall (Ottenheijm et al. 2005 p200). The solid relationship that exists
between the measures of Pdi and sMMGdi in the healthy patient shows that MMG provides a
clinically appropriate noninvasive index of the diaphragm muscles and the chest wall
contractility in individuals with long-lasting obstreperous pulmonic disease (Numis et al. 2014
p6). Therefore, it is evident that the use of MMG to determine the severity of COPD improves
the evaluation of the inspiratory muscle activation in the clinical setup. This technique has led to
a well understanding of the continuing obstructive lung disease. The measurements of the
diaphragmatic function and performance have a role in the early assessment of the exacerbation
of COPD and can be used to predict the response to therapy (Crisafulli, Costi, Fabbri & Clini,
2007 p21).

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