Effect of respiratory muscle training on load sensations in people with chronic tetraplegia: a secondary analysis of a randomised controlled trial.

STUDY DESIGN: Secondary analysis of a randomised controlled trial. OBJECTIVES: Our primary study showed that increasing inspiratory muscle strength with training in people with chronic (>1 year) tetraplegia corresponded with reduced sensations of breathlessness when inspiration was loaded. This study investigated whether respiratory muscle training also affected the respiratory sensations for load detection and magnitude perception. SETTING: Independent research institute in Sydney, Australia. METHODS: Thirty-two adults with chronic tetraplegia participated in a 6-week, supervised training protocol. The active group trained the inspiratory muscles through progressive threshold loading. The sham group performed the same protocol with a fixed threshold load (3.6 cmH2O). Primary measures were load detection threshold and perceived magnitudes of six suprathreshold loads reported using the modified Borg scale. RESULTS: Maximal inspiratory pressure (PImax) increased by 32% (95% CI, 18-45) in the active group with no change in the sham group (p =  0.51). The training intervention did not affect detection thresholds in the active (p =  0.24) or sham (p =  0.77) group, with similar overall decreases in Borg rating of 0.83 (95% CI, 0.49-1.17) in active and 0.72 (95% CI, 0.32-1.12) in sham group. Increased inspiratory muscle strength reduced slope magnitude between Borg rating and peak inspiratory pressure (p =  0.003), but not when pressure was divided by PImax to reflect contraction intensity (p =  0.92). CONCLUSIONS: Training reduces the sensitivity of load sensations for a given change in pressure but not for a given change in contraction intensity.

Comparison of two inspiratory muscle training protocols in people with spinal cord injury: a secondary analysis.

STUDY DESIGN/SETTING: Secondary analysis. OBJECTIVES: To compare the change in maximal inspiratory pressure (PImax) over the first 4 weeks of two different inspiratory muscle training (IMT) protocols and explore if either method is more effective for people with spinal cord injury. METHODS: Data originated from two published studies. Participants completed flow-resistive IMT (F-IMT) at 80% daily PImax, 7 days/week (supervised weekly), or threshold IMT (T-IMT) at 30-80% weekly PImax, twice-daily, 5 days/week (supervised every session). Seven participants from each trial were matched by training adherence, level of spinal cord injury, impairment grade (A-C), and height. Differences between F-IMT and T-IMT groups in training intensity, breaths taken, inspiratory work, and the change in the PImax from baseline at the end of week four were analysed. RESULTS: Over 4 weeks, there was no difference in the change in PImax between groups (Absolute change in PImax (cmH2O): p = 0.456, Percent change in PImax relative to baseline: p = 0.128). F-IMT participants trained at a higher intensity (median: 77 vs 22 cmH2O, p = 0.001 and 80% baseline vs 61% baseline, p = 0.038) but took fewer breaths (840 vs 1404 breaths, p = 0.017) than T-IMT participants. Inspiratory work was similar between groups (64,789 vs 65,910 (% PImax × number of breaths), p = 0.535). CONCLUSIONS: Our findings support both methods of IMT as the change in PImax and inspiratory work were similar between groups. However, daily high-intensity F-IMT with intermittent supervision, required fewer breaths and less participant and therapist time. Future studies should examine optimal dosage and supervision required to achieve increased PImax.

Transcutaneous spinal stimulation in people with and without spinal cord injury: Effect of electrode placement and trains of stimulation on threshold intensity.

Transcutaneous spinal cord stimulation (TSS) is purported to improve motor function in people after spinal cord injury (SCI). However, several methodology aspects are yet to be explored. We investigated whether stimulation configuration affected the intensity needed to elicit spinally evoked motor responses (sEMR) in four lower limb muscles bilaterally. Also, since stimulation intensity for therapeutic TSS (i.e., trains of stimulation, typically delivered at 15-50 Hz) is sometimes based on the single-pulse threshold intensity, we compared these two stimulation types. In non-SCI participants (n = 9) and participants with a SCI (n = 9), three different electrode configurations (cathode-anode); L1-midline (below the umbilicus), T11-midline and L1-ASIS (anterior superior iliac spine; non-SCI only) were compared for the sEMR threshold intensity using single pulses or trains of stimulation which were recorded in the vastus medialis, medial hamstring, tibialis anterior, medial gastrocnemius muscles. In non-SCI participants, the L1-midline configuration showed lower sEMR thresholds compared to T11-midline (p = 0.002) and L1-ASIS (p < 0.001). There was no difference between T11-midline and L1-midline for participants with SCI (p = 0.245). Spinally evoked motor response thresholds were ~13% lower during trains of stimulation compared to single pulses in non-SCI participants (p < 0.001), but not in participants with SCI (p = 0.101). With trains of stimulation, threshold intensities were slightly lower and the incidence of sEMR was considerably lower. Overall, stimulation threshold intensities were generally lower with the L1-midline electrode configuration and is therefore preferred. While single-pulse threshold intensities may overestimate threshold intensities for therapeutic TSS, tolerance to trains of stimulation will be the limiting factor in most cases.

Respiratory-related evoked potentials in chronic obstructive pulmonary disease and healthy aging.

Altered neural processing and increased respiratory sensations have been reported in chronic obstructive pulmonary disease (COPD) as larger respiratory-related evoked potentials (RREPs), but the effect of healthy-aging has not been considered adequately. We tested RREPs evoked by brief airway occlusions in 10 participants with moderate-to-severe COPD, 11 age-matched controls (AMC) and 14 young controls (YC), with similar airway occlusion pressure stimuli across groups. Mean age was 76 years for COPD and AMC groups, and 30 years for the YC group. Occlusion intensity and unpleasantness was rated using the modified Borg scale, and anxiety rated using the Hospital Anxiety and Depression Scale. There was no difference in RREP peak amplitudes across groups, except for the N1 peak, which was significantly greater in the YC group than the COPD and AMC groups (p = 0.011). The latencies of P1, P2 and P3 occurred later in COPD versus YC (p < 0.05). P3 latency occurred later in AMC than YC (p = 0.024). COPD and AMC groups had similar Borg ratings for occlusion intensity (3.0 (0.5, 3.5) [Median (IQR)] and 3.0 (3.0, 3.0), respectively; p = 0.476) and occlusion unpleasantness (1.3 (0.1, 3.4) and 1.0 (0.75, 2.0), respectively; p = 0.702). The COPD group had a higher anxiety score than AMC group (p = 0.013). A higher N1 amplitude suggests the YC group had higher cognitive processing of respiratory inputs than the COPD and AMC groups. Both COPD and AMC groups showed delayed neural responses to the airway occlusion, which may indicate impaired processing of respiratory sensory inputs in COPD and healthy aging.

Effectiveness of Abdominal Functional Electrical Stimulation for Improving Bowel Function in People With a Spinal Cord Injury: A Study Protocol for a Double-Blinded Randomized Placebo-Controlled Clinical Trial.

Background: People with a spinal cord injury (SCI) have a high rate of bowel-related morbidity, even compared with people with other neurological disorders. These complications lower quality of life and place a financial burden on the health system. A noninvasive intervention that improves the bowel function of people with an SCI should reduce morbidity, improve quality of life, and lead to cost savings for health care providers. Objectives: To investigate the effectiveness of noninvasive abdominal functional electrical stimulation (FES) for improving bowel function in people with a chronic SCI. Methods: A prospective, double-blinded, 1:1 randomized, placebo-controlled intervention trial will be conducted with 80 adults with chronic SCI (>12 months since injury) above T8 single neurological level. The intervention will be a 45-minute abdominal FES (or placebo) session, 3 days per week, for 6 weeks. Main Study Parameters/Endpoints: Primary endpoint is whole gut transit time before and after 6 weeks of abdominal FES. Secondary endpoints measured before and after 6 weeks of abdominal FES are (1) colonic transit time; (2) quality of life (EQ-5D-5L); (3) participant-reported bowel function (International SCI Bowel Function Basic Data Set Questionnaire and visual analogue scale); (4) respiratory function (forced vital capacity, forced expiratory volume in 1 second, peak expiratory flow, maximal inspiratory pressure, and maximal expiratory pressure); (5) bladder symptoms (Neurogenic Bladder Symptom Score); (6) daily bowel management diary; and (7) unplanned hospital visits. Conclusion: Safety data will be collected, and a cost utility analysis using quality of life scores will be performed. Trial registration: Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12621000386831.

Inspiratory muscle reflex control after incomplete cervical spinal cord injury.

In healthy individuals, loading inspiratory muscles by brief inspiratory occlusion produces a short-latency inhibitory reflex (IR) in the electromyographic (EMG) activity of scalene and diaphragm muscles. This IR may play a protective role to prevent aspiration and airway collapse during sleep. In people with motor and sensory complete cervical spinal cord injury (cSCI), who were able to breathe independently, this IR was predominantly absent. Here, we investigated the reflex response to brief airway occlusion in 16 participants with sensory incomplete cSCI [American spinal injury association impairment scale (AIS) score B or C]. Surface EMG was recorded from scalene muscles and the lateral chest wall (overlying diaphragm). The airway occlusion evoked a small change in mouth pressure resembling a physiological occlusion. The short-latency IR was present in 10 (63%) sensory incomplete cSCI participants; significantly higher than the IR incidence observed in complete cSCI participants in our previous study (14%; P = 0.003). When present, mean IR latency across all muscles was 58 ms (range 29-79 ms), and mean rectified EMG amplitude decreased to 37% preocclusion levels. Participants without an IR had untreated severe obstructive sleep apnea (OSA), in contrast to those with an IR, who had either had no, mild, or treated OSA (P = 0.002). Insufficient power did not allow statistical comparison between IR presence or absence and participant clinical characteristics. In conclusion, spared sensory connections or intersegmental connections may be necessary to generate the IR. Future studies to establish whether IR presence is related to respiratory morbidity in the tetraplegic population are required.NEW & NOTEWORTHY Individuals with incomplete cSCI were tested for the presence of a short latency reflex inhibition of inspiratory muscles, by brief airway occlusion. The reflex was 4.5 times more prevalent in this group compared with those with complete cSCI and is similar to the incidence in able-bodied people. Participants without this reflex all had untreated severe OSA, in contrast to those with an IR, who either had no, mild, or treated OSA. This work reveals novel differences in the reflex control of inspiratory muscles across the cSCI population.

The detection and sensory perception of inspiratory resistive loads in people with chronic tetraplegia.

This study investigated sensations of breathing following tetraplegia. Fifteen people with chronic tetraplegia and fifteen healthy able-bodied controls matched for age, sex, height, and weight participated. Sensations of breathing were quantified by determining the threshold for detecting an added resistance during inspiration. In a separate task, the perceived magnitudes of six suprathreshold resistive loads were determined with a modified Borg scale. The detection threshold of 0.34 cmH2O/L/s [standard deviation (SD) 0.14] in the tetraplegia group was higher than the 0.23 cmH2O/L/s (SD 0.10) threshold for able-bodied controls (P = 0.004). Both participant groups perceived larger loads to be more effortful, with the Borg effort rating increasing linearly with the peak inspiratory pressure generated at each load. The relationship between Borg effort rating and peak inspiratory pressure was steeper in participants with tetraplegia than in able-bodied controls (P = 0.001), but there was no difference when pressure was divided by maximal inspiratory pressure (P = 0.95). Despite a higher detection threshold, the findings suggest that the perceived magnitude of a suprathreshold inspiratory load is not impaired in chronic tetraplegia and that load magnitude perception is related to the maximal, and not absolute, inspiratory muscle force.NEW & NOTEWORTHY Sensations of breathing are thought to be impaired following chronic tetraplegia. The detection threshold for an added resistive load during inspiration was higher in people with tetraplegia than in healthy able-bodied participants. However, for inspiratory loads above the detection threshold, the perceived magnitude of a resistive load as a function of the peak inspiratory pressure was greater in tetraplegia. Load magnitude perception was comparable between participant groups when peak pressure was divided by maximal inspiratory pressure.

Transcutaneous spinal cord stimulation combined with locomotor training to improve walking ability in people with chronic spinal cord injury: study protocol for an international multi-centred double-blinded randomised sham-controlled trial (eWALK).

STUDY DESIGN: An international multi-centred, double-blinded, randomised sham-controlled trial (eWALK). OBJECTIVE: To determine the effect of 12 weeks of transcutaneous spinal stimulation (TSS) combined with locomotor training on walking ability in people with spinal cord injury (SCI). SETTING: Dedicated SCI research centres in Australia, Spain, USA and Scotland. METHODS: Fifty community-dwelling individuals with chronic SCI will be recruited. Participants will be eligible if they have bilateral motor levels between T1 and T11, a reproducible lower limb muscle contraction in at least one muscle group, and a Walking Index for SCI II (WISCI II) between 1 and 6. Eligible participants will be randomised to one of two groups, either the active stimulation group or the sham stimulation group. Participants allocated to the stimulation group will receive TSS combined with locomotor training for three 30-min sessions a week for 12 weeks. The locomotor sessions will include walking on a treadmill and overground. Participants allocated to the sham stimulation group will receive the same locomotor training combined with sham stimulation. The primary outcome will be walking ability with stimulation using the WISCI II. Secondary outcomes will record sensation, strength, spasticity, bowel function and quality of life. TRIAL REGISTRATION: ANZCTR.org.au identifier ACTRN12620001241921.

Tongue strength and swallowing dynamics in chronic obstructive pulmonary disease.

BACKGROUND: Swallowing disorders occur in COPD, but little is known about tongue strength and mastication. This is the first assessment in COPD of tongue strength and a test of mastication and swallowing solids (TOMASS). METHODS: Anterior tongue strength measures were obtained in 18 people with COPD, aged 73±11 years (mean±sd), and 19 healthy age-matched controls, aged 72±6 years. Swallowing dynamics were assessed using an eating assessment tool (EAT-10), timed water swallow test (TWST), and TOMASS. Swallowing measures were compared to an inhibitory reflex (IR) in the inspiratory muscles to airway occlusion (recorded previously in the same participants). RESULTS: Tongue strength was similar between COPD and controls (p=0.715). Self-assessed scores of dysphagia EAT-10 were higher (p=0.024) and swallowing times were prolonged for liquids (p=0.022) and solids (p=0.003) in the COPD group. During TWST, ∼30% of COPD group showed clinical signs of airway invasion (cough and wet voice), but none in the control group. For solids, the COPD group had ∼40% greater number of chews (p=0.004), and twofold-higher number of swallows (p=0.0496). Respiratory rate was 50% higher in COPD group than controls (p <0.001). The presence of an IR was not related to better swallowing outcomes, but signs of airway invasion were associated with a delayed IR. CONCLUSION: Dysphagia in stable COPD is not due to impaired anterior tongue strength, but rather swallowing-breathing discoordination. To address dysphagia, aspiration and acute exacerbations in COPD, therapeutic targets to improve swallowing dynamics could be investigated further.

Inspiratory muscle responses to sudden airway occlusion in chronic obstructive pulmonary disease.

Brief airway occlusion produces a potent reflex inhibition of inspiratory muscles that is thought to protect against aspiration. Its duration is prolonged in asthma and obstructive sleep apnea. We assessed this inhibitory reflex (IR) in chronic obstructive pulmonary disease (COPD). Reflex responses to brief (250 ms) inspiratory occlusions were measured in 18 participants with moderate to severe COPD (age 73 ± 11 yr) and 17 healthy age-matched controls (age 72 ± 6 yr). We compared the incidence and properties of the IR between groups. Median eupneic preocclusion electromyographic activity was higher in the COPD group than controls (9.4 µV vs. 5.2 µV, P = 0.001). Incidence of the short-latency IR was higher in the COPD group compared with controls (15 participants vs. 7 participants, P = 0.010). IR duration for scalenes was similar for the COPD and control groups [73 ± 37 ms (means ± SD) and 90 ± 50 ms, respectively] as was the magnitude of inhibition. IRs in the diaphragm were not detected in the controls but were present in 9 participants of the COPD group (P = 0.001). The higher incidence of the IR in the COPD group than in the age-matched controls may reflect the increased inspiratory neural drive in the COPD group. This higher drive counteracts changes in chest wall and lung mechanics. However, when present, the reflex was similar in size and duration in the two groups. The relation between the IR in COPD and swallowing function could be assessed.NEW & NOTEWORTHY A potent short-latency reflex inhibition of inspiratory muscles produced by airway occlusion was tested in people with COPD and age-matched controls. The reflex was more prevalent in COPD, presumably due to an increased neural drive to breathe. When present, the reflex was similar in duration in the two groups, longer than historical data for younger control groups. The work reveals novel differences in reflex control of inspiratory muscles due to aging as well as COPD.

Breath-synchronized electrical stimulation of the expiratory muscles in mechanically ventilated patients: a randomized controlled feasibility study and pooled analysis.

BACKGROUND: Expiratory muscle weakness leads to difficult ventilator weaning. Maintaining their activity with functional electrical stimulation (FES) may improve outcome. We studied feasibility of breath-synchronized expiratory population muscle FES in a mixed ICU population ("Holland study") and pooled data with our previous work ("Australian study") to estimate potential clinical effects in a larger group. METHODS: Holland: Patients with a contractile response to FES received active or sham expiratory muscle FES (30 min, twice daily, 5 days/week until weaned). Main endpoints were feasibility (e.g., patient recruitment, treatment compliance, stimulation intensity) and safety. Pooled: Data on respiratory muscle thickness and ventilation duration from the Holland and Australian studies were combined (N = 40) in order to estimate potential effect size. Plasma cytokines (day 0, 3) were analyzed to study the effects of FES on systemic inflammation. RESULTS: Holland: A total of 272 sessions were performed (active/sham: 169/103) in 20 patients (N = active/sham: 10/10) with a total treatment compliance rate of 91.1%. No FES-related serious adverse events were reported. Pooled: On day 3, there was a between-group difference (N = active/sham: 7/12) in total abdominal expiratory muscle thickness favoring the active group [treatment difference (95% confidence interval); 2.25 (0.34, 4.16) mm, P = 0.02] but not on day 5. Plasma cytokine levels indicated that early FES did not induce systemic inflammation. Using a survival analysis approach for the total study population, median ventilation duration and ICU length of stay were 10 versus 52 (P = 0.07), and 12 versus 54 (P = 0.03) days for the active versus sham group. Median ventilation duration of patients that were successfully extubated was 8.5 [5.6-12.2] versus 10.5 [5.3-25.6] days (P = 0.60) for the active (N = 16) versus sham (N = 10) group, and median ICU length of stay was 10.5 [8.0-14.5] versus 14.0 [9.0-19.5] days (P = 0.36) for those active (N = 16) versus sham (N = 8) patients that were extubated and discharged alive from the ICU. During ICU stay, 3/20 patients died in the active group versus 8/20 in the sham group (P = 0.16). CONCLUSION: Expiratory muscle FES is feasible in selected ICU patients and might be a promising technique within a respiratory muscle-protective ventilation strategy. The next step is to study the effects on weaning and ventilator liberation outcome. TRIAL REGISTRATION: ClinicalTrials.gov, ID NCT03453944. Registered 05 March 2018-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03453944 .

The reliability of inspiratory resistive load magnitude and detection testing.

OBJECTIVES: To assess the test-retest reliability of inspiratory load detection and load magnitude perception tests in healthy volunteers. DESIGN: Cohort of convenience. SETTING: Respiratory physiology laboratory. PARTICIPANTS: Twenty healthy adults. INTERVENTIONS: On two separate occasions participants performed tests of inspiratory loading. Participants breathed through custom made resistive tubing and were asked to indicate when they detected a different resistance during inspiration. In a second test participants rated the magnitude of presented inspiratory loads using the modified Borg score. MAIN OUTCOME MEASURES: Intra-class Correlation Coefficient (ICC2,1) values for repeated tests of inspiratory load detection threshold and load magnitude rating. RESULTS: ICC2,1 values ranged from 0.657-0.786 for load detection testing and 0.739 to 0.969 for rating of load magnitude. CONCLUSIONS: The tests are simple and reliable measures of inspiratory load detection and magnitude rating. They can be used in future research to determine the effectiveness of interventions to reduce the effort of breathing in health and disease.

Absence of inspiratory premotor potentials during quiet breathing in cervical spinal cord injury.

A premotor potential, or Bereitschaftspotential (BP), is a low-amplitude negativity in the electroencephalographic activity (EEG) of the sensorimotor cortex. It begins ~1 s prior to the onset of inspiration in the averaged EEG. Although normally absent during quiet breathing in healthy, younger people, inspiration-related BPs are present in people with respiratory disease and healthy, older people, indicating a cortical contribution to quiet breathing. People with tetraplegia have weak respiratory muscles and increased neural drive during quiet breathing, indicated by increased inspiratory muscle activity. Therefore, we hypothesized that BPs would be present during quiet breathing in people with tetraplegia. EEG was recorded in 17 people with chronic tetraplegia (14M, 3 female; 22-51 yr; C3-C7, American Spinal Injury Association Impairment Scale A-D; >1 yr postinjury). They had reduced lung function and respiratory muscle weakness [FEV1: 54 ± 19% predicted, FVC: 59 ± 22% predicted and MIP: 56 ± 24% predicted (mean ± SD)]. Participants performed quiet breathing and voluntary self-paced sniffs (positive control condition). A minimum of 250 EEG epochs during quiet breathing and 60 epochs during sniffs, time-locked to the onset of inspiration, were averaged to determine the presence of BPs at Cz, FCz, C3, and C4. Fifteen participants (88%) had a BP for the sniffs. Of these 15 participants, only one (7%) had a BP in quiet breathing, a rate similar to that reported during quiet breathing in young able-bodied participants (12%). The findings suggest that, as in young able-bodied people, a cortical contribution to quiet breathing is absent in people with tetraplegia despite higher neural drive.NEW & NOTEWORTHY People with tetraplegia have weak respiratory muscles, increased neural drive during quiet breathing, and a high incidence of sleep-disordered breathing. Using electroencephalographic recordings, we show that inspiratory premotor potentials are absent in people with chronic tetraplegia during quiet breathing. This suggests that cortical activity is not present during resting ventilation in people with tetraplegia who are awake and breathing independently.

The effects of 10,000 voluntary contractions over 8 weeks on the strength of very weak muscles in people with spinal cord injury: a randomised controlled trial.

STUDY DESIGN: A multi-centred, single-blinded randomised controlled trial. OBJECTIVES: To determine the effect of 10,000 voluntary contractions over 8 weeks on the strength of very weak muscles in people with spinal cord injury (SCI). SETTINGS: Seven hospitals in Australia and Asia. METHODS: One hundred and twenty people with recent SCI undergoing inpatient rehabilitation were randomised to either a Treatment or Control Group. One major muscle group from an upper or lower limb was selected if the muscle had grade 1 or grade 2 strength on a standard six-point manual muscle test. Participants allocated to the Treatment Group performed 10,000 isolated contractions of the selected muscle group, as well as usual care in 48 sessions over 8 weeks. Participants allocated to the Control Group received usual care alone. Participants were assessed at baseline and 8 weeks by a blinded assessor. The primary outcome was voluntary muscle strength on a 13-point manual muscle test. There were three secondary outcomes capturing therapists' and participants' perceptions of strength and function. RESULTS: The mean between-group difference of voluntary strength at 8 weeks was 0.4/13 points (95% confidence interval -0.5 to 1.4) in favour of the Treatment Group. There were no notable between-group differences on any secondary outcome. CONCLUSION: Ten thousand isolated contractions of very weak muscles in people with SCI over 8 weeks has either no or a very small effect on voluntary strength.

Impact of respiratory muscle training on respiratory muscle strength, respiratory function and quality of life in individuals with tetraplegia: a randomised clinical trial.

BACKGROUND: Respiratory complications remain a leading cause of morbidity and mortality in people with acute and chronic tetraplegia. Respiratory muscle weakness following spinal cord injury-induced tetraplegia impairs lung function and the ability to cough. In particular, inspiratory muscle strength has been identified as the best predictor of the likelihood of developing pneumonia in individuals with tetraplegia. We hypothesised that 6 weeks of progressive respiratory muscle training (RMT) increases respiratory muscle strength with improvements in lung function, quality of life and respiratory health. METHODS: Sixty-two adults with tetraplegia participated in a double-blind randomised controlled trial. Active or sham RMT was performed twice daily for 6 weeks. Inspiratory muscle strength, measured as maximal inspiratory pressure (PImax) was the primary outcome. Secondary outcomes included lung function, quality of life and respiratory health. Between-group comparisons were obtained with linear models adjusting for baseline values of the outcomes. RESULTS: After 6 weeks, there was a greater improvement in PImax in the active group than in the sham group (mean difference 11.5 cmH2O (95% CI 5.6 to 17.4), p<0.001) and respiratory symptoms were reduced (St George Respiratory Questionnaire mean difference 10.3 points (0.01-20.65), p=0.046). Significant improvements were observed in quality of life (EuroQol-Five Dimensional Visual Analogue Scale 14.9 points (1.9-27.9), p=0.023) and perceived breathlessness (Borg score 0.64 (0.11-1.17), p=0.021). There were no significant improvements in other measures of respiratory function (p=0.126-0.979). CONCLUSIONS: Progressive RMT increases inspiratory muscle strength in people with tetraplegia, by a magnitude which is likely to be clinically significant. Measurement of baseline PImax and provision of RMT to at-risk individuals may reduce respiratory complications after tetraplegia. TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN 12612000929808).

The effect of abdominal functional electrical stimulation on bowel function in multiple sclerosis: a cohort study.

BACKGROUND: Chronic constipation is prevalent in people with multiple sclerosis, with current treatments usually only partially effective. OBJECTIVES: This study aims to evaluate the efficacy of abdominal functional electrical stimulation to reduce whole gut and colonic transit times and improve bowel and bladder-related quality of life. METHODS: A total of 23 people with multiple sclerosis who fulfilled the Rome III criteria for functional constipation applied abdominal functional electrical stimulation for 1 hour per day, 5 days per week, for 6 weeks. Whole gut and colonic transit times and bowel and bladder-related quality of life were measured before and after the intervention period. RESULTS: Whole gut (mean 81.3 (standard deviation 28.7) hours pre vs. 96.1 (standard deviation 53.6) hours post-intervention, P = 0.160) and colonic transit time (65.1 (31.4) vs. 74.8 (51.1) hours, P = 0.304) were unchanged following 6 weeks of abdominal functional electrical stimulation. There was a significant improvement in bowel (mean 1.78 (SD: 0.64) pre vs. 1.28 (SD: 0.54) post, P = 0.001) and bladder (50.6 (26.49) vs. 64.5 (21.92), p = 0.007) related quality of life after the intervention period. CONCLUSION: While abdominal functional electrical stimulation did not reduce whole gut and colonic transit times for people with multiple sclerosis, a significant improvement in bowel and bladder-related quality of life was reported.

The frequency of bowel and bladder problems in multiple sclerosis and its relation to fatigue: A single centre experience.

BACKGROUND: Bowel and bladder problems affect more than 50% of people with Multiple Sclerosis (MS). These problems have a large impact on quality of life and place a significant burden on health systems. OBJECTIVES: This study aimed to ascertain the frequency of bladder and bowel problems in a select Australian MS cohort and to investigate the relationships between level of disability, bladder and bowel problems, and fatigue. METHODS: Questionnaires on the nature and severity of MS symptoms were distributed to clients attending an Australian MS centre. Log-binomial regression and multiple linear regression models were used to investigate relationships between disability, fatigue, and bladder and bowel problems. RESULTS AND CONCLUSIONS: Of 167 questionnaires distributed, 136 were completed. Bladder problems were reported by 87 (74.4%) respondents, whilst 66 (48.9%) experienced functional constipation and 43 (31.9%) faecal incontinence. This frequency in our select Australian MS population is similar to that reported globally. There was a significant correlation between level of disability and: bladder problems (p = 0.015), faecal incontinence (p = 0.001), fatigue (p<0.001) and constipation (p = 0.016, relative risk: 1.16). Further investigation into the causal relationships between various MS symptoms may be beneficial in the development of novel therapeutic strategies for people with MS.

Abdominal functional electrical stimulation to assist ventilator weaning in critical illness: a double-blinded, randomised, sham-controlled pilot study.

BACKGROUND: For every day a person is dependent on mechanical ventilation, respiratory and cardiac complications increase, quality of life decreases and costs increase by > $USD 1500. Interventions that improve respiratory muscle function during mechanical ventilation can reduce ventilation duration. The aim of this pilot study was to assess the feasibility of employing an abdominal functional electrical stimulation (abdominal FES) training program with critically ill mechanically ventilated patients. We also investigated the effect of abdominal FES on respiratory muscle atrophy, mechanical ventilation duration and intensive care unit (ICU) length of stay. METHODS: Twenty critically ill mechanically ventilated participants were recruited over a 6-month period from one metropolitan teaching hospital. They were randomly assigned to receive active or sham (control) abdominal FES for 30 min, twice per day, 5 days per week, until ICU discharge. Feasibility was assessed through participant compliance to stimulation sessions. Abdominal and diaphragm muscle thickness were measured using ultrasound 3 times in the first week, and weekly thereafter by a blinded assessor. Respiratory function was recorded when the participant could first breathe independently and at ICU discharge, with ventilation duration and ICU length of stay also recorded at ICU discharge by a blinded assessor. RESULTS: Fourteen of 20 participants survived to ICU discharge (8, intervention; 6, control). One control was transferred before extubation, while one withdrew consent and one was withdrawn for staff safety after extubation. Median compliance to stimulation sessions was 92.1% (IQR 5.77%) in the intervention group, and 97.2% (IQR 7.40%) in the control group (p = 0.384). While this pilot study is not adequately powered to make an accurate statistical conclusion, there appeared to be no between-group thickness changes of the rectus abdominis (p = 0.099 at day 3), diaphragm (p = 0.652 at day 3) or combined lateral abdominal muscles (p = 0.074 at day 3). However, ICU length of stay (p = 0.011) and ventilation duration (p = 0.039) appeared to be shorter in the intervention compared to the control group. CONCLUSIONS: Our compliance rates demonstrate the feasibility of using abdominal FES with critically ill mechanically ventilated patients. While abdominal FES did not lead to differences in abdominal muscle or diaphragm thickness, it may be an effective method to reduce ventilation duration and ICU length of stay in this patient group. A fully powered study into this effect is warranted. TRIAL REGISTRATION: The Australian New Zealand Clinical Trials Registry, ACTRN12617001180303. Registered 9 August 2017.

The effect of paired corticospinal-motoneuronal stimulation on maximal voluntary elbow flexion in cervical spinal cord injury: an experimental study.

STUDY DESIGN: Randomised, controlled, crossover study. OBJECTIVES: Paired corticospinal-motoneuronal stimulation (PCMS) involves repeatedly pairing stimuli to corticospinal neurones and motoneurones to induce changes in corticospinal transmission. Here, we examined whether PCMS could enhance maximal voluntary elbow flexion in people with cervical spinal cord injury. SETTING: Neuroscience Research Australia, Sydney, Australia. METHODS: PCMS comprised 100 pairs of transcranial magnetic and electrical peripheral nerve stimulation (0.1 Hz), timed so corticospinal potentials arrived at corticospinal-motoneuronal synapses 1.5 ms before antidromic motoneuronal potentials. On two separate days, sets of five maximal elbow flexions were performed by 11 individuals with weak elbow flexors post C4 or C5 spinal cord injury before and after PCMS or control (100 peripheral nerve stimuli) conditioning. During contractions, supramaximal biceps brachii stimulation elicited superimposed twitches, which were expressed as a proportion of resting twitches to give maximal voluntary activation. Maximal torque and electromyographic activity were also assessed. RESULTS: Baseline median (range) maximal torque was 11 Nm (6-41 Nm) and voluntary activation was 92% (62-99%). Linear mixed modelling revealed no significant differences between PCMS and control protocols after conditioning (maximal torque: p = 0.87, superimposed twitch: p = 0.87, resting twitch: p = 0.44, voluntary activation: p = 0.36, biceps EMG: p = 0.25, brachioradialis EMG: 0.67). CONCLUSIONS: Possible explanations for the lack of effect include a potential ceiling effect for voluntary activation, or that PCMS may be less effective for elbow flexors than distal muscles. Despite results, previous studies suggest that PCMS is worthy of further investigation.

Inspiratory pre-motor potentials during quiet breathing in ageing and chronic obstructive pulmonary disease.

KEY POINTS: A cortical contribution to breathing, as indicated by a Bereitschaftspotential (BP) in averaged electroencephalographic signals, occurs in healthy individuals when external inspiratory loads are applied. Chronic obstructive pulmonary disease (COPD) is a condition where changes in the lung, chest wall and respiratory muscles produce an internal inspiratory load. These changes also occur in normal ageing, although to a lesser extent. In the present study, we determined whether BPs are present during quiet breathing and breathing with an external inspiratory load in COPD compared to age-matched and young healthy controls. We demonstrated that increased age, rather than COPD, is associated with a cortical contribution to quiet breathing. A cortical contribution to inspiratory loading is associated with more severe dyspnoea (i.e. the sensation of breathlessness). We propose that cortical mechanisms may be engaged to defend ventilation in ageing with dyspnoea as a consequence. ABSTRACT: A cortical contribution to breathing is determined by the presence of a Bereitschaftspotential, a low amplitude negativity in the averaged electroencephalographic (EEG) signal, which begins ∼1 s before inspiration. It occurs in healthy individuals when external inspiratory loads to breathing are applied. In chronic obstructive pulmonary disease (COPD), changes in the lung, chest wall and respiratory muscles produce an internal inspiratory load. We hypothesized that there would be a cortical contribution to quiet breathing in COPD and that a cortical contribution to breathing with an inspiratory load would be linked to dyspnoea, a major symptom of COPD. EEG activity was analysed in 14 participants with COPD (aged 57-84 years), 16 healthy age-matched (57-87 years) and 15 young (18-26 years) controls during quiet breathing and inspiratory loading. The presence of Bereitschaftspotentials, from ensemble averages of EEG epochs at Cz and FCz, were assessed by blinded assessors. Dyspnoea was rated using the Borg scale. The incidence of a cortical contribution to quiet breathing was significantly greater in participants with COPD (6/14) compared to the young (0/15) (P = 0.004) but not the age-matched controls (6/16) (P = 0.765). A cortical contribution to inspiratory loading was associated with higher Borg ratings (P = 0.007), with no effect of group (P = 0.242). The data show that increased age, rather than COPD, is associated with a cortical contribution to quiet breathing. A cortical contribution to inspiratory loading is associated with more severe dyspnoea. We propose that cortical mechanisms may be engaged to defend ventilation with dyspnoea as a consequence.