Investigation of inspiratory intercostal muscle activity in patients with spinal cord injury: a pilot study using electromyography, ultrasonography, and respiratory inductance plethysmography.

[Purpose] 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.

Reliability of voluntary cough assessments using respiratory flow waveform.

[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.

Measurement of intercostal muscle thickness with ultrasound imaging during maximal breathing.

[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.

Oxygen cost of thoracic and diaphragmatic breathing during hyperventilation in healthy males.

[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.

Maximal respiratory pressure in healthy Japanese children.

[Purpose] Normal values for respiratory muscle pressures during development in Japanese children have not been reported. The purpose of this study was to investigate respiratory muscle pressures in Japanese children aged 3-12 years. [Subjects and Methods] We measured respiratory muscle pressure values using a manovacuometer without a nose clip, with subjects in a sitting position. Data were collected for ages 3-6 (Group I: 68 subjects), 7-9 (Group II: 86 subjects), and 10-12 (Group III: 64 subjects) years. [Results] The values for respiratory muscle pressures in children were significantly higher with age in both sexes, and were higher in boys than in girls. Correlation coefficients were significant at values of 0.279 to 0.471 for each gender relationship between maximal respiratory pressure and age, height, and weight, respectively. [Conclusion] In this study, we showed pediatric respiratory muscle pressure reference value for each age. In the present study, values for respiratory muscle pressures were lower than Brazilian studies. This suggests that differences in respiratory muscle pressures vary with ethnicity.

Axonal projection of the medullary expiratory neurons in the feline thoracic spinal cord.

Expiratory neurons in the caudal ventral respiratory group extend descending axons to the lumbar and sacral spinal cord, and they possess axon collaterals, the distribution of which has been well-documented. Likewise, these expiratory neurons extend axons to the thoracic spinal cord and innervate thoracic expiratory motoneurons. These axons also give rise to collaterals, and their distribution may influence the strength of synaptic connectivity between the axons and the thoracic expiratory motoneurons. We investigated the distribution of axon collaterals in the thoracic spinal cord using a microstimulation technique. This study was performed on cats; one cat was used to make an anatomical atlas and six were used in the experiment. Extracellular spikes of expiratory neurons were recorded in artificially ventilated cats. The thoracic spinal gray matter was microstimulated from dorsal to ventral sites at 100-µm intervals using a glass-insulated tungsten microelectrode with a current of 150-250 µA. The stimulation tracks were made at 1 mm intervals along the spinal cord in segments Th9 to Th13, and the effective stimulating sites of antidromic activation in axon collaterals were systematically mapped. The effective stimulating sites in the contralateral thoracic spinal cord with expiratory neurons in the caudal ventral respiratory group (cVRG) occupied 14.4% of the total length of the thoracic spinal cord examined. The mean percentage of effective stimulating tracks per unit was 18.6 ± 4.4%. The distribution of axon collaterals of expiratory neurons in the feline thoracic spinal cord indeed resembled that reported in the upper lumbar spinal cord. We propose that a single medullary expiratory neuron exerts excitatory effects across multiple segments of the thoracic spinal cord via its collaterals.

Correlation of cervical-inspiratory-muscle electromyography and oxygen uptake during treadmill walking.

For measurements of exercise intensity, an individual's oxygen uptake (V̇O2) is measured with an exhaled gas analyzer that involves a mask, but exercise coaching would benefit if an individual's V̇O2 could be estimated with more easily obtained predictors. We investigated the predictability of V̇O2 by electromyography (EMG) of the neck inspiratory muscles. We analyzed the EMG results of the sternocleidomastoid (EMGst) and scalene (EMGsc) muscles of 14 healthy adults who performed a treadmill exercise load test. Their V̇O2, inspiratory flow rate, and heart rate were simultaneously recorded during the exercise. The exercise load test was performed twice at a ≥2-day interval. The first visit was an incremental exercise test, and the second was a repeated two-load exercise test at levels below and above the participant's ventilatory threshold (VT) as determined in the first test. We observed that the integrated EMG values for each exercise load showed partially significant positive correlations with the EMGst and EMGsc. However, the cervical inspiratory muscle EMGs did not show as high a correlation as the minute ventilation. These results indicate that (i) EMG of the cervical inspiratory muscles could be used to estimate V̇O2, but (ii) these EMG parameters alone should be considered insufficient for estimating V̇O2.

Rib cage contributions to inspiratory capacity in patients with cervical spinal cord injury.

Background: Cervical spinal cord injury (CSI) often leads to impaired respiratory function, affecting the overall well-being of patients. This study aimed to investigate the influence of rib cage motion on inspiratory capacity in CSI patients. Methods: We conducted a study with 11 CSI patients, utilising respiratory inductance plethysmography (RIP). We measured ventilatory volume by spirometry concurrently with RIP. Participants were instructed to perform maximal inspiratory efforts. Inspiratory capacity (IC) was calculated from spirometry waveforms. We converted the respiratory waveforms of the chest and abdomen into inspiratory volume measured by a spirometer. The inspiratory volume measured by the chest sensor was defined as VRIP-rib cage (VRIP-rc), and the inspiratory volume measured by the abdominal sensor was defined as VRIP-abdomen (VRIP-ab). Subsequently, the relationships of IC with VRIP-rc and VRIPab were assessed. Results: The mean IC was 1.828 ± 0.459 L, with the mean VRIP-rc at 1.343 ± 0.568 L and the mean VRIP-ab at 0.485 ± 0.427 L. A significant correlation was observed between IC and VRIP-rc (r = 0.67, p = 0.02), indicating that rib cage motion significantly influences IC in CSI patients. Conclusion: This study highlights the importance of rib cage motion in assessing inspiratory capacity in patients with CSI.

Routine hypercapnic challenge after cervical spinal hemisection affects the size of phrenic motoneurons.

After an individual experiences a cervical cord injury, the cell body's adaptation to the smaller size of phrenic motoneurons occurs within several weeks. It is not known whether a routine hypercapnic load can alter this adaptation of phrenic motoneurons. We investigated this question by using rats with high cervical cord hemisection. The rats were divided into four groups: control, hypercapnia, sham, and sham hypercapnia. Within 72 h post-hemisection, the hypercapnia groups began a hypercapnic challenge (20 min/day, 4 times/week for 3 weeks) with 7% CO2 under awake conditions. After the 3-week challenge, the phrenic motoneurons in all of the rats were retrogradely labeled with horseradish peroxidase, and the motoneuron sizes in each group were compared. The average diameter, cross-sectional area, and somal surface area of stained phrenic motoneurons as analyzed by software were significantly smaller in only the control group compared to the other groups. The histogram distribution was unimodal, with larger between-group size differences for motoneurons in the horizontal plane than in the transverse plane. Our findings indicate that a routine hypercapnic challenge may increase the input to phrenic motoneurons and alter the propensity for motoneuron adaptations.

Effect of a weekly functional independence measure scale on the recovery of patient with acute stroke: A retrospective study.

ABSTRACT: Excessive assistance may decrease stroke patients' physical activity and make them more dependent on assistance. We have structured a system that provides an ADL (activities of daily living) educational program that focuses on stroke patients' toileting in our daily clinical practice. Here, we investigated the effect of a functional independence measure (FIM) scale on the recovery of patients with acute stroke.We retrospectively collected the data of 407 stroke patients from the medical record system of our emergency hospital in Tsukuba, Japan. The enrolled stroke patients (n = 373) were divided into FIM and control groups. Both groups received the standard treatment, but for the FIM group, ward and rehabilitation staff calculated the toilet FIM score for patients 1 ×/wk. The FIM scale measures the amount of assistance a patient needs to perform activities of daily living and is often used in rehabilitation settings. The rehabilitation staff then instructed the ward staff about better assistance methods based on each patient's physical function and executive dysfunction. We evaluated the usefulness of the FIM scale was based on the patients' FIM scores at discharge and improvements in their scores.The recoveries of the total, motor, and cognitive FIM scores recovery at discharge were significantly greater in the FIM group compared with the control group (68.0 vs 45.0, P = .004; 41.0 vs 24.0, P = .005; and 24.0 vs 20.0, P = .007, respectively). The use of the FIM scale contributes to the patients' recovery of physical function and cognitive function.The FIM scale can contribute to stroke patients' recovery of activities of daily living.

Features of electromyography threshold of the respiratory muscles during incremental exercise test.

In this study, we aimed to examine the electromyography threshold (EMGT) of the respiratory muscle and accessory respiratory muscles. Sixteen healthy men underwent an incremental exercise test at 15 W/minute to the end point. Expired gases and electromyograms of the respiratory and lower limb muscles were measured. The breakpoints for the EMG and expired gas data were analyzed using a segmented regression model. EMGT of the sternocleidomastoid and diaphragm was significantly more delayed than the ventilation threshold (VT) (287.94 s, 288.15 s vs. 185.5 s, p = 0.028 and 0.044, respectively). The EMGT of respiratory muscles and VT were not related, though EMGT of rectus femoris and vastus lateralis correlated with VT (r = 0.854, p < 0.001; r = 0.657, p = 0.011, respectively). EMGT of respiratory muscles may be influenced by multiple factors, such as central command and afferent input of mechanical stimulation from muscles, in addition to VT-induced changes in metabolic dynamics.

Effects of breathing control using visual feedback of thoracoabdominal movement on aerobic exercise.

PURPOSE: To clarify whether voluntary respiratory movement control strategy is sustainable during exercise and to determine its effect on aerobic exercise. MATERIAL AND METHODS: Ten healthy men were enrolled in this study. We developed a device that can convert information on thoracoabdominal changes from an inductance plethysmograph and display the Konno-Mead diagram on the monitor in real time for each breath. On the first day, an incremental load test (ILT) was performed under two conditions. On the second day, a constant load test (CLT) was performed under two conditions using the load 1 min before the anaerobic threshold (AT). RESULTS: In the ILT, a significant prolongation of AT time was observed with voluntary respiratory movement control. In the CLT, carbon dioxide excretion showed no significant interaction, but the gas exchange ratio did. CONCLUSION: Voluntary respiratory movement control using a combination of chest band and visual feedback of thoracoabdominal movements may be a respiratory strategy to enhance aerobic exercise.

Effects of visual feedback of thoracoabdominal motion on oxygen consumption during hyperventilation - Pilot study.

INTRODUCTION: Respiratory muscle oxygen consumption increases with the work of breathing. We hypothesized that reducing excessive respiratory muscle activity during exercise may improve exercise tolerance. METHOD: We developed a device to provide real-time visual feedback of thoracoabdominal movement and used it to examine the influence of visual feedback of thoracoabdominal movement during diaphragmatic breathing on oxygen consumption in eight healthy men. While sitting on a wheelchair with the backrest reclined at 60°, oxygen consumption per body weight (VO2/BW), minute ventilation (VE), tidal volume (VT), and breathing frequency (fR) were measured, breath-by-breath, using an expired-gas analyzer. The breathing pattern was analyzed by inductance plethysmography, with transducer bands over the chest and abdomen recording thoracoabdominal movements. RESULTS: There was no significant difference in RatioTH-ABD and the ventilatory parameters between diaphragmatic breathing and diaphragmatic breathing with visual feedback. The average VO2/BW during diaphragmatic breathing with visual feedback was 0.6 ml/kg lower than that during diaphragmatic breathing without visual feedback (p<0.05). CONCLUSION: When visual feedback was used during diaphragmatic breathing, the RatioTH-ABD remained essentially unchanged, but VO2/BW decreased significantly. This suggests that visual feedback of thoracoabdominal movement during diaphragmatic breathing may reduce respiratory muscle oxygen consumption.

Ipsilesional spatial bias after a focal cerebral infarction in the medial agranular cortex: A mouse model of unilateral spatial neglect.

Unilateral spatial neglect is a disorder of higher brain function that occurs after a brain injury, such as stroke, traumatic brain injury, brain tumor, and surgical procedures etc., and leads to failure to attend or respond to stimuli presented to the side contralateral to the lesioned cerebral hemisphere. Because patients with this condition often have other symptoms due to the presence of several brain lesions, it is difficult to evaluate the recovery mechanisms and effect of training on unilateral spatial neglect. In this study, a mouse model of unilateral spatial neglect was created to investigate whether the size of the lesion is related to the severity of ipsilesional spatial bias and the recovery process. Focal infarction was induced in the right medial agranular cortex (AGm) of mice via photothrombosis. After induction of cerebral infarction, ipsilesional spatial bias was evaluated for 9 consecutive days. The major findings were as follows: (1) unilateral local infarction of the AGm resulted in ipsilateral bias during internally guided decision-making; (2) the lesion size was correlated with the degree of impairment rather than slight differences in the lesion site; and (3) mice with anterior AGm lesions experienced lower recovery rates. These findings suggest that recovery from ipsilesional spatial bias requires neural plasticity within the anterior AGm. This conditional mouse model of ipsilesional spatial bias may be used to develop effective treatments for unilateral spatial neglect in humans.

Investigation into the mobility of elderly patients with pneumonia using triaxial accelerometer data.

OBJECTIVE: This study aimed to clarify the levels of physical activity of elderly pneumonia patients. METHOD: This is a prospective observational study among pneumonia patients who were hospitalized in a clinic within a general and respiratory medicine hospital department, and community-dwelling elderly. Activity levels of 29 elderly patients with pneumonia who were aged >75 years (PP group), and 15 community-dwelling healthy elderly (CD group) were measured. Triaxial accelerometers were attached to the patients' left chest regions from 48 h until 7 days after hospitalization. RESULTS: The time spent in the upright position was 320.0 min/day in the PP group and 729.0 min/day in the CD group. The time spent walking was 3.8 min/day in the PP group, and 71.0 min/day in the CD group. In the PP group, the times spent in the upright position and walking did not increase during the period studied, that is, from 48 h until 7 days after hospitalization. CONCLUSION: The time spent in the upright position and walking among elderly patients with pneumonia did not increase, despite gradual improvement of the disease.