[Purpose] Determining the thickness of the intercostal muscle with ultrasound imaging
would be a useful parameter in evaluating respiratory muscle activity in patients with
tetraplegia and neuromuscular weakness. However, it has not been clarified whether
ultrasound imaging can measure changes in intercostal muscle thickness during breathing.
This study aimed to measure contractions of the human intercostal muscle in the anterior,
lateral, and posterior parts with ultrasound imaging during maximal breathing.
[Participants and Methods] The participants were 12 healthy males. Intercostal muscle
thickness was measured using ultrasound at rest and at maximal breathing. The measurement
sites were the anterior, lateral, and posterior portions of the right intercostal spaces.
Statistical analysis was performed using a paired t-test comparing intercostal muscle
thickness at rest and maximal breathing. [Results] The thickness of the intercostal muscle
showed significant increases in the first, second, third, fourth, and sixth intercostal
spaces of the anterior portions. There were no significant differences in the lateral or
posterior portions between rest and maximal breathing. [Conclusion] Human intercostal
muscle thickness can be measured with ultrasound and increases only in the anterior
portions during maximal breathing.
[Purpose] Voluntary cough can be assessed by recording flow waves. The purpose of this
study was to examine the reliability of the measurements of respiratory flow waveforms,
using equipment that recorded flow waves during cough. [Participants and Methods] Twenty
healthy participants were recruited for this study. They underwent spirometry on them and,
subsequently, their flow waves during single and consecutive voluntary cough tasks in the
sitting position were recorded. The intra-class correlation coefficient was used to assess
the intra-rater and inter-rater reliabilities for the voluntary cough data. [Results] The
intra-class correlation coefficients were 0.6 to 0.8 for ‘intra-rater reliability’ and
higher than 0.9 for ‘inter-rater reliability’, for single and consecutive cough tasks. The
first assessment of cough peak flow was significantly higher than the second, during
consecutive cough tasks. Similarly, the first assessment of cough volume acceleration was
significantly higher than the second. [Conclusion] Our results demonstrated high
intra-rater and inter-rater reliabilities for single and consecutive cough tasks.
Following additional procedures and valuations, including the storage of data and standard
range decisions, this method of cough assessment will be applied to patients with reduced
cough function.
[Purpose] It is unclear whether diaphragmatic breathing (DB) results in lower respiratory
muscle oxygen consumption during dynamic exercise. The purpose of this study was to
compare oxygen consumption in the respiratory muscles (VO2rm) with
thoracic breathing (TB) and with DB, in healthy males during hyperventilation. [Subjects
and Methods] Ten healthy men participated in this study. The subjects sat on a chair with
the backrest reclined at an angle of 60 degrees. Respiratory parameters were measured
breath by breath, using an expired gas analyzer. Oxygen consumption was measured for three
minutes during quiet breathing. Measurements during TB and DB were performed for one
minute each, after connecting a rebreather loading device. The breathing pattern was
analyzed by inductance plethysmography, using transducer bands placed over the chest and
abdomen that recorded thoracoabdominal movements. [Results] Both ΔVO2/body
weight and VO2rm decreased significantly with DB when compared to that
with TB, during hyperventilation. [Conclusion] DB results in less respiratory muscle
oxygen consumption, even during dynamic exercise.
The respiratory function in patients with cervical spinal cord injury is influenced by inspiratory intercostal muscle function. However, inspiratory intercostal muscle activity has not been conclusively evaluated. We evaluated the inspiratory intercostal muscle activity in patients with cervical spinal cord injury by using inspiratory intercostal electromyography, respiratory inductance plethysmography, and ultrasonography. [Participants and Methods] Three patients with cervical spinal cord injury were assessed. The change in mean amplitude (rest vs. maximum inspiration) was calculated by using intercostal muscle electromyography. Changes in intercostal muscle thickness (resting expiration and maximum inspiration) were also evaluated on ultrasonography. The waveform was converted to spirometry ventilation with respiratory inductance plethysmography, and the waveform at the xiphoid was considered to determine the rib cage volume. Each index was compared with the inspiratory capacities in each case. [Results] Intercostal muscle electromyography failed to measure the notable myoelectric potential in all the patients. The rib cage volume was higher at higher inspiratory capacities. The changes in muscle thickness were not significantly different between the patients. [Conclusion] The rib cage volume (measured with inductance plethysmography) was greater in the patients with cervical spinal cord injury when inspiratory intercostal muscle activity was high. Respiratory inductance plethysmography can capture inspiratory intercostal muscle function in patients with cervical spinal cord injury.
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