Claire L. Boswell-Ruys

Surface Functional Electrical Stimulation of the Abdominal Muscles to Enhance Cough and Assist Tracheostomy Decannulation After High-Level Spinal Cord Injury

Abstract Objective: Evaluation of noninvasive stimulation modalities to augment cough and assist tracheostomy decannulation in high-level tetraplegia. Study Design: Single case study. Methods: A 65-year-old man with C4 ASIA C tetraplegia had delayed rehabilitation due to a tracheostomy and recurrent pneumonia primarily resulting from ineffective cough. Anterior surface electrical stimulation (SES) of the abdominal musculature was conducted to train an effective cough and enable decannulation. Training occurred daily for 4 weeks. The patient was tested 1 year later with posterolateral SES to determine the relative clinical effect of this delivery method. Results: At baseline, the addition of anterior SES increased maximal expiratory pressure (80%), maximal expiratory cough pressure (67%), and peak expiratory flow rate (11 %). Three weeks after training began, the patient was decannulated following a program of SES and assisted and voluntary coughing. Upon testing 1 year later, SES with posterolaterally placed electrodes also produced an enhancement of voluntary cough attempts. Conclusions: Noninvasive SES can potentially assist decannulation of tracheostomies.

Validity and Reliability of Assessment Tools for Measuring Unsupported Sitting in People With a Spinal Cord Injury

OBJECTIVES To develop simple tests to assess the abilities of people with spinal cord injury (SCI) to sit unsupported and to assess the construct validity and test-retest reliability of these tests. DESIGN Cross-sectional comparisons, convenience sample. SETTING Biomechanical laboratory. PARTICIPANTS People (N=30) with SCI between the C6 and the L2 level of 2 months to 37 years duration before assessment. The sample was stratified by impairment level (at T8) and time since injury (1 y postinjury). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES On 2 separate occasions, participants performed tests that measured the distance of upper-body sway and maximal torso leaning, errors made during a coordinated stability task, timed dressing/undressing of the upper body and alternating arm reaching, and percentage change in seated upper body/arm reaching. RESULTS All tests showed good construct validity in that they distinguished between participants with higher (C6-T7) and lower (T8-L2) level impairments (P<.05) and between participants with acute (< or =1 y) and chronic (>1 y) lesions (P<.05). The tests also showed good to excellent test-retest reliability (intraclass correlation coeffiecient(3,1) range, .51-.91). CONCLUSIONS These simple and quick-to-administer tests have both construct validity and test-retest reliability. They would be appropriate for research and clinical purposes to quantify the abilities of people with SCI to sit unsupported.

Abdominal Muscle Training Can Enhance Cough After Spinal Cord Injury

Background. Respiratory complications in people with high-level spinal cord injury (SCI) are a major cause of morbidity and mortality, particularly because of a reduced ability to cough as a result of abdominal muscle paralysis. Objective. We investigated the effect of cough training combined with functional electrical stimulation (FES) over the abdominal muscles for 6 weeks to observe whether training could improve cough strength. Methods. Fifteen SCI subjects (C4-T5) trained for 6 weeks, 5 days per week (5 sets of 10 coughs per day) in a randomized crossover design study. Subjects coughed voluntarily at the same time as a train of electrical stimulation was delivered over the abdominal muscles via posterolaterally positioned electrodes (50 Hz, 3 seconds). Measurements were made of esophageal (Pes) and gastric (Pga) expiratory pressures and the peak expiratory flow (PEFcough) produced at the 3 time points of before, during, and after the training. Results. During voluntary coughs, FES cough stimulation improved Pga, Pes, and PEFcough acutely, 20-fold, 4-fold, and 50%, respectively. Six weeks of cough training significantly increased Pga (37.1 ± 2.0 to 46.5 ± 2.9 cm H2O), Pes (35.4 ± 2.7 to 48.1 ± 2.9 cm H2O), and PEFcough (3.1 ± 0.1 to 3.6 ± 0.1 L/s). Cough training also improved pressures and flow during voluntary unstimulated coughs. Conclusions. FES of abdominal muscles acutely increases mechanical output in coughing in high-level SCI subjects. Six weeks of cough training further increases gastric and esophageal cough pressures and expiratory cough flow during stimulated cough maneuvers.

Posterolateral Surface Electrical Stimulation of Abdominal Expiratory Muscles to Enhance Cough in Spinal Cord Injury

Background. Spinal cord injury (SCI) patients have respiratory complications because of abdominal muscle weakness and paralysis, which impair the ability to cough. Objective. This study aims to enhance cough in high-level SCI subjects (n = 11, SCI at or above T6) using surface electrical stimulation of the abdominal muscles via 2 pairs of posterolaterally placed electrodes. Methods. From total lung capacity, subjects performed maximum expiratory pressure (MEP) efforts against a closed airway and voluntary cough efforts. Both efforts were performed with and without superimposed trains of electrical stimulation (50 Hz, 1 second) at a submaximal intensity set to evoke a gastric pressure (P ga) of 40 cm H2O at functional residual capacity. Results. In the MEP effort, stimulation increased the maximal P ga (from 21.4 ± 7.0 to 59.0 ± 5.7 cm H2O) and esophageal pressure (P es; 47.2 ± 11.7 to 65.6 ± 13.6 cm H2O). During the cough efforts, stimulation increased P ga (19.5 ± 6.0 to 57.9 ± 7.0 cm H2O) and P es (31.2 ± 8.7 to 56.6 ± 10.5 cm H2O). The increased expiratory pressures during cough efforts with stimulation increased peak expiratory flow (PEF, by 36% ± 5%), mean expiratory flow (by 80% ± 8%), and expired lung volume (by 41% ± 16%). In every subject, superimposed electrical stimulation improved peak expiratory flow during cough efforts (by 0.99 ± 0.12 L/s; range, 0.41-1.80 L/s). Wearing an abdominal binder did not improve stimulated cough flows or pressures. Conclusions. The increases in P ga and PEF with electrical stimulation using the novel posterolateral electrode placement are 2 to 3 times greater than improvements reported in other studies. This suggests that posterolateral electrical stimulation of abdominal muscles is a simple noninvasive way to enhance cough in individuals with SCI.

Training unsupported sitting in people with chronic spinal cord injuries: a randomized controlled trial.

Study design:Randomized, assessor-blinded trial.Objectives:To evaluate the effectiveness of a 6-week task-specific training programme on the abilities of people with chronic spinal cord injuries to sit unsupported.Setting:NSW, Australia.Methods:Thirty adults with spinal cord injuries of at least 1-year duration were recruited. Participants in the training group (n=15) performed up to 1 h of task-specific training three times a week for 6 weeks. Participants in the control group (n=15) did not receive any training or additional therapy. Primary outcome measures were the Canadian Occupational Performance Measure (COPM), and tests of Upper Body Sway, Maximal Balance Range and donning and doffing a T-shirt (the T-shirt test).Results:The between-group mean difference (95% confidence interval) for the maximal balance range was 64 mm (95% confidence interval 20 to 108 mm; P=0.006). There were no significant between-group mean differences for the COPM and the Upper Body Sway and T-shirt tests.Conclusions:This trial shows initial support for intensive task-specific training for improving the abilities of people with chronic spinal cord injuries to sit unsupported, although the real-world implications of the observed treatment effects are yet to be determined.

A Falls Concern Scale for people with spinal cord injury (SCI-FCS)

Study design:Observational study and cross-sectional survey.Objectives:To develop a scale assessing concern about falling in people with spinal cord injuries who are dependent on manual wheelchairs, and to evaluate psychometric properties of this new scale.Setting:Community and hospitals, Australia.Methods:The Spinal Cord Injury-Falls Concern Scale (SCI-FCS) was developed in consultation with SCI professionals. The SCI-FCS addressed concern about falling during 16 activities of daily living associated with falling and specific to people with SCI. One hundred and twenty-five people with either acute or chronic SCI who used manual wheelchairs were assessed on the SCI-FCS and asked questions related to their SCI and overall physical abilities. A subgroup of 20 people was reassessed on the SCI-FCS within 7 days.Results:The SCI-FCS had excellent internal and test–retest reliability (Cronbachs α=0.92, intra-class correlation coefficient (ICC)=0.93). Factor analysis revealed three underlying dimensions of the SCI-FCS addressing concern about falling during activities that limit hand support and require movement of the bodys centre of mass. The discriminative ability of the SCI-FCS between different diagnostic groups indicated good construct validity. Subjects with a high level of SCI, few previous falls, dependence in vertical transfers and poor perceived sitting ability demonstrated high levels of concern about falling.Conclusions:This study suggests that the SCI-FCS is a valid and reliable tool for assessing concern about falling in people with SCI dependent on manual wheelchairs. The SCI-FCS could also assist in determining the effectiveness of fall minimization programs.

Electrical Stimulation of Abdominal Muscles to Produce Cough in Spinal Cord Injury Effect of Stimulus Intensity

Background. Surface electrical stimulation of the abdominal muscles, with electrodes placed in the posterolateral position, combined with a voluntary cough can assist clearance of airway secretions in individuals with high-level spinal cord injury (SCI). Objective. To determine whether an increase in stimulus intensity of the trains of electrical stimuli delivered to the expiratory muscles has an increasing effect on a stimulated voluntary cough and to determine at which stimulus intensity a plateau of cough peak expiratory flow occurs. Methods. In 7 healthy individuals with a SCI at and above C7, gastric pressure (Pga), esophageal pressure (Pes), peak expiratory cough flow (PEFcough), and expiratory volume were measured as participants coughed voluntarily with simultaneous trains of electrical stimuli delivered over the abdominal muscles (50 Hz, 1-s duration). The intensity of the stimulation was increased incrementally. Results: A plateau in PEFcough occurred in all 7 individuals at a mean of 211 ± 29 mA (range 120-360 mA). Peak values reached for Pga, Pes, and PEFcough were 83.0 ± 8.0 cm H2O, 66.1 ± 5.6 cm H2O, and 4.0 ± 0.4 l/s respectively. Conclusions. The plateau in expiratory cough flow that was associated with increasing expiratory pressures is indicative of dynamic airway compression. This suggests that the evoked cough will be effective in creating more turbulent airflow to further assist in dislodging mucus and secretions.

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

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.

Optimal electrode position for abdominal functional electrical stimulation

Abdominal functional electrical stimulation (abdominal FES) improves respiratory function. Despite this, clinical use remains low, possibly due to lack of agreement on the optimal electrode position. This study aimed to ascertain the optimal electrode position for abdominal FES, assessed by expiratory twitch pressure. Ten able-bodied participants received abdominal FES using electrodes placed: 1) on the posterolateral abdominal wall and at the motor points of 2) the external oblique muscles plus rectus abdominis muscles, and 3) the external obliques alone. Gastric (Pga) and esophageal (Pes) twitch pressures were measured using a gastroesophageal catheter. Single-stimulation pulses were applied at functional residual capacity during step increments in stimulation current to maximal tolerance or until Pga plateaued. Stimulation applied on the posterolateral abdominal wall led to a 71% and 53% increase in Pga and Pes, respectively, compared with stimulation of the external oblique and rectus abdominis muscles ( P < 0.001) and a 95% and 56% increase in Pga and Pes, respectively, compared with stimulation of the external oblique muscles alone ( P < 0.001). Stimulation of both the external oblique and rectus abdominis muscles led to an 18.3% decrease in Pga compared with stimulation of only the external oblique muscles ( P = 0.040), with inclusion of the rectus abdominis having no effect on Pes ( P = 0.809). Abdominal FES applied on the posterolateral abdominal wall generated the highest expiratory twitch pressures. As expiratory pressure is a good indicator of expiratory muscle strength and, thus, cough efficacy, we recommend this electrode position for all therapeutic applications of abdominal FES. NEW & NOTEWORTHY While abdominal functional electrical stimulation (abdominal FES) can improve respiratory function, clinical use remains low. This is at least partly due to lack of agreement on the optimal electrode position. Therefore, this study aimed to ascertain the optimal electrode position for abdominal FES. We show that electrodes placed on the posterolateral abdominal wall generated the highest expiratory twitch pressures. As such, we recommend this electrode position for all therapeutic applications of abdominal FES.

Respiratory muscle training may improve respiratory function and obstructive sleep apnoea in people with cervical spinal cord injury.

Study design:This is a double-blind crossover case study series.Objectives:The objective of this study was to assess the feasibility of respiratory muscle training (RMT) as an effective intervention to improve lung function and obstructive sleep apnoea (OSA) in cervical spinal cord injury (SCI) patients.Setting:This study was conducted in Australia.Methods:Three adults (C5–6, AIS A–C) participated in this study. They trained with an RMT device (active or sham) for 4 weeks followed by 2 weeks of rest, and then trained with the alternate device for 4 weeks. RMT occurred twice daily, 5 days a week, and it consisted of three sets of 12 inspirations and three sets of 12 expirations. Training intensity commenced at 30% maximal inspiratory pressure (MIP) and 30% maximal expiratory pressure (MEP), which was increased every second day by 10%. Spirometry, MIP, MEP, polysomnography and Epworth Sleepiness Scale (ESS) were measured before and after every 4 weeks of training.Results:After active RMT, vital capacity and inspiratory capacity improved from baseline in all participants (by 44%, 60% and 18% and by 18%, 46% and 5%, respectively); MIP improved by 40 and 17% from baseline in two subjects; and MEP improved in all participants. Two participants had OSA, and after active training their obstructive apnoea–hypopnoea index improved from 30 to 21events per hour and from 72 to 18 events per hour, and ESS marginally improved. Sham RMT resulted in minimal changes in all measures.Conclusion:RMT is feasible and likely effective to increase respiratory muscle strength, to improve lung function, and to reduce the severity of OSA and sleepiness in people with cervical SCI. A randomised controlled trial is planned to validate these findings and to examine respiratory-related morbidity and quality of life.