Changes in pulmonary function measures following a passive abdominal functional electrical stimulation training program

The effect of electromyography triggered electrical stimulation to abdominal muscles on sitting balance, respiratory functions, and abdominal muscle thickness in complete spinal cord injury: a randomized controlled trial

Complete thoracic spinal cord injury (SCI) results in a loss of innervation to the abdominal muscles, which affects trunk stability and performance of activities of daily living from a sitting position. Respiratory function is also affected, leading to frequent pulmonary complications. Given the importance of trunk stability and respiratory function, we investigated the effects of electromyography triggered electrical stimulation (EMG-ES) applied to the abdominal muscles on sitting balance, respiratory functions and abdominal muscle thickness in individuals with complete thoracic SCI. This randomized controlled study included 34 participants with complete thoracic SCI who were randomly allocated to the experimental group ( n  = 17) and the control group ( n  = 17). During the 4-week intervention period, the experimental group received EMG-ES to their abdominal muscles, while the control group received isometric abdominal exercises three times per week. Both groups continued with their routine rehabilitation program (active or passive range of motion exercises, stretching, and balance coordination exercises). The primary outcome measures were the modified functional reach test (mFRT) and trunk control test (TCT). Secondary outcome measures included a pulmonary function test (PFT) and the bilateral abdominal muscle thicknesses using ultrasonography. At the end of the study, the experimental group showed significantly greater improvements in both primary outcomes. The mean difference in pre-post changes between the groups for the mFRT area was 242.8 cm² [95% confidence interval (CI): 181.3-329.8; effect size 0.92; P  < 0.001] and 5.0 points for TCT (95% CI: 3.9-6.0; effect size 0.98, P  < 0.001). The increase in the abdominal muscle thickness was also significantly greater in the experimental group ( P  < 0.001) without significant differences in the PFT ( P  > 0.05). We conclude that adding EMG-ES of abdominal muscles may further improve sitting balance and abdominal muscle thickness in individuals with complete thoracic SCI.

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.

Oropharyngeal Dysphagia in Acute Cervical Spinal Cord Injury: A Literature Review

Dysphagia (swallowing impairment) is a frequent complication of cervical spinal cord injury (cSCI). Recently published national guidance in the UK on rehabilitation after traumatic injury confirmed that people with cSCI are at risk for dysphagia and require early evaluation while remaining nil by mouth [National Institute for Health and Care Excellence. Rehabilitation after traumatic injury (NG211), 2022, https://www.nice.org.uk/guidance/ng21]. While the pathogenesis and pathophysiology of dysphagia in cSCI remains unclear, numerous risk factors have been identified in the literature. This review aims to summarize the literature on the risk factors, presentation, assessment, and management of dysphagia in patients with cSCI. A bespoke approach to dysphagia management, that accounts for the multiple system impairment in cSCI, is presented; the overarching aim of which is to support effective management of dysphagia in patients with cSCI to prevent adverse clinical consequences.

A Review of Different Stimulation Methods for Functional Reconstruction and Comparison of Respiratory Function after Cervical Spinal Cord Injury

Background

Spinal cord injury (SCI) is a common severe trauma in clinic, hundreds of thousands of people suffer from which every year in the world. In terms of injury location, cervical spinal cord injury (CSCI) has the greatest impact. After cervical spinal cord injury, the lack of innervated muscles is not enough to provide ventilation and other activities to complete the respiratory function. In addition to the decline of respiratory capacity, respiratory complications also have a serious impact on the life of patients. The most commonly used assisted breathing and cough equipment is the ventilator, but in recent years, the functional electrical stimulation method is being used gradually and widely.

Methods

About hundred related academic papers are cited for data analysis. They all have the following characteristics: (1) basic conditions of patients were reported, (2) patients had received nerve or muscle stimulation and the basic parameters, and (3) the results were evaluated based on some indicators.

Results

The papers mentioned above are classified as four kinds of stimulation methods: muscle electric/magnetic stimulation, spinal dural electric stimulation, intraspinal microstimulation, and infrared light stimulation. This paper describes the stimulation principle and application experiment. Finally, this paper will compare the indexes and effects of typical stimulation methods, as well as the two auxiliary methods: training and operation.

Conclusions

Although there is limited evidence for the treatment of respiratory failure by nerve or muscle stimulation after cervical spinal cord injury, the two techniques seem to be safe and effective. At the same time, light stimulation is gradually applied to clinical medicine with its strong advantages and becomes the development trend of nerve stimulation in the future.

ICT-Based Health Care Services for Individuals with Spinal Cord Injuries: A Feasibility Study

In the Republic of Korea, 90.5% of those living with spinal cord injury (SCI) are faced with medical complications that require chronic care. Some of the more common ones include urinary tract infections, pressure sores, and pain symptomatology. These and other morbidities have been recognized to deteriorate the individual's health, eventually restricting their community participation. Telerehabilitation, using information and communication technology, has propelled a modern-day movement in providing comprehensive medical services to patients who have difficulty in mobilizing themselves to medical care facilities. This study aims to verify the effectiveness of health care and management in the SCI population by providing ICT-based health care services. We visited eight individuals living with chronic SCI in the community, and provided ICT-based health management services. After using respiratory and urinary care devices with the provision of home visit occupational therapy, data acquisition was achieved and subsequently entered into a smart device. The entered information was readily accessible to the necessary clinicians and researchers. The clients were notified if there were any concerning results from the acquired data. Subsequently, they were advised to follow up with their providers for any immediate medical care requirements. Digital hand-bike ergometers and specialized seating system cushions are currently in development. The ICT-based health care management service for individuals with SCI resulted in a favorable expected level of outcome. Based on the results of this study, we have proposed and are now in preparation for a randomized clinical trial.

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 (P_ga) and esophageal (P_es) 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 P_ga plateaued. Stimulation applied on the posterolateral abdominal wall led to a 71% and 53% increase in P_ga and P_es, respectively, compared with stimulation of the external oblique and rectus abdominis muscles ( P < 0.001) and a 95% and 56% increase in P_ga and P_es, 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 P_ga compared with stimulation of only the external oblique muscles ( P = 0.040), with inclusion of the rectus abdominis having no effect on P_es ( 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.

Novas perspectivas de fisioterapia respiratória em lesão medular - uma revisão sistemática

Resumo Objetivo: Descrever e analisar parâmetros e efeitos da estimulação elétrica de superfície na função muscular respiratória de pessoas com lesão medular, sobretudo durante a tosse. Métodos: Foi realizada uma revisão sistemática da literatura, com base no Preferred Reporting items for Systematic Reviews and Meta-Analyses. A busca foi realizada nas bases de dados PubMed, PEDro e LILACS, por meio dos seguintes descritores: “estimulação elétrica funcional”, “eletroestimulação, estimulação elétrica”, “tosse”, “higiene brônquica”, “quadriplegia”, “lesão medular espinhal”, “tetraplegia” e “sujeito com tetraplegia” - em espanhol, inglês e português, sem restrição quanto ao ano de publicação. Foram incluídos artigos com amostra de indivíduos com lesão medular assistidos por estimulação elétrica com desfecho relacionado ao sistema respiratório, e foram excluídos artigos com ensaios invasivos de estímulo a tosse. Resultados: Os 12 artigos incluídos revelam heterogeneidade nos protocolos de eletroestimulação da função expiratória, que podem incluir frequências de 30 a 50 Hz, com pulsos de 25 a 400 μs, aplicada por até oito eletrodos distribuídos pelos músculos expiratórios e acessórios. O tempo de aplicação também foi variável e a amplitude de corrente frequentemente estimada pela percepção do paciente, podendo chegar a valores superiores a 100mA. Conclusão: Apesar de não ser possível estabelecer parâmetros rigorosos de fisioterapia por meio da estimulação elétrica, pela escassez e qualidade de estudos que comparem sistematicamente parâmetros de estimulação em subgrupos, foram observadas alterações positivas nas variáveis de função muscular respiratória avaliadas, como o pico de fluxo expiratório e de tosse, em pessoas com lesão medular cervical e torácica.

Abdominal functional electrical stimulation to enhance mechanical insufflation-exsufflation

CONTEXT

Respiratory complications, attributed to the build-up of secretions in the airway, are a leading cause of rehospitalisation for the tetraplegic population. Previously, we observed that the application of Abdominal Functional Electrical Stimulation (AFES) improved cough function and increased demand for secretion removal, suggesting AFES may aid secretion clearance. Clinically, secretion clearance is commonly achieved by using Mechanical insufflation-exsufflation (MI-E) to simulate a cough. In this study the feasibility of combining AFES with MI-E is evaluated.

FINDINGS

AFES was successfully combined with MI-E at eight fortnightly assessment sessions conducted with one sub-acute participant with tetraplegia. By using the signal from a pressure sensor, integrated with the MI-E device, AFES was correctly applied in synchrony with MI-E with an accuracy of 96.7%. Acute increases in exhaled volume and peak flow were observed during AFES assisted MI-E, compared to MI-E alone, at six of eight assessment sessions.

CONCLUSION

The successful integration of AFES with MI-E at eight assessment sessions demonstrates the feasibility of this technique. The acute increases in respiratory function observed at the majority of assessment sessions generate the hypothesis that AFES assisted MI-E may be more effective for secretion clearance than MI-E alone.

Breathing-synchronised electrical stimulation of the abdominal muscles in patients with acute tetraplegia: A prospective proof-of-concept study

OBJECTIVE

To examine whether, by enhancing breathing depth and expectoration, early use of breathing-synchronised electrical stimulation of the abdominal muscles (abdominal functional electrical stimulation, AFES) is able to reduce pulmonary complications during the acute phase of tetraplegia.

DESIGN

Prospective proof-of-concept study.

SETTING

Spinal cord unit at a level 1 trauma center.

METHOD

Following cardiovascular stabilisation, in addition to standard treatments, patients with acute traumatic tetraplegia (ASIA Impairment Scale A or B) underwent breathing-synchronised electrical stimulation of the abdominal muscles to aid expiration and expectoration. The treatment was delivered in 30-minute sessions, twice a day for 90 days. The target was for nine of 15 patients to remain free of pneumonia meeting Centers for Disease Control and Prevention (CDC) diagnostic criteria.

RESULTS

Eleven patients were recruited to the study between October 2011 and November 2012. Two patients left the study before completion. None of the patients contracted pneumonia during the study period. No complications from electrical stimulation were observed. AFES led to a statistically significant increase in peak inspiratory and expiratory flows and a non-statistically significant increase in tidal volume and inspiratory and expiratory flow. When surveyed, 6 out of 9 patients (67%) reported that the stimulation procedure led to a significant improvement in breathing and coughing.

CONCLUSION

AFES appears to be able to improve breathing and expectoration and prevent pneumonia in the acute phase of tetraplegia (up to 90 days post-trauma). This result is being validated in a prospective multicentre comparative study.

Abdominal functional electrical stimulation to improve respiratory function after spinal cord injury: a systematic review and meta-analysis

OBJECTIVES

Abdominal functional electrical stimulation (abdominal FES) is the application of a train of electrical pulses to the abdominal muscles, causing them to contract. Abdominal FES has been used as a neuroprosthesis to acutely augment respiratory function and as a rehabilitation tool to achieve a chronic increase in respiratory function after abdominal FES training, primarily focusing on patients with spinal cord injury (SCI). This study aimed to review the evidence surrounding the use of abdominal FES to improve respiratory function in both an acute and chronic manner after SCI.

SETTINGS

A systematic search was performed on PubMed, with studies included if they applied abdominal FES to improve respiratory function in patients with SCI.

METHODS

Fourteen studies met the inclusion criteria (10 acute and 4 chronic). Low participant numbers and heterogeneity across studies reduced the power of the meta-analysis. Despite this, abdominal FES was found to cause a significant acute improvement in cough peak flow, whereas forced exhaled volume in 1 s approached significance. A significant chronic increase in unassisted vital capacity, forced vital capacity and peak expiratory flow was found after abdominal FES training compared with baseline.

CONCLUSIONS

This systematic review suggests that abdominal FES is an effective technique for improving respiratory function in both an acute and chronic manner after SCI. However, further randomised controlled trials, with larger participant numbers and standardised protocols, are needed to fully establish the clinical efficacy of this technique.

Abdominal Functional Electrical Stimulation to Assist Ventilator Weaning in Acute Tetraplegia: A Cohort Study

Background

Severe impairment of the major respiratory muscles resulting from tetraplegia reduces respiratory function, causing many people with tetraplegia to require mechanical ventilation during the acute stage of injury. Abdominal Functional Electrical Stimulation (AFES) can improve respiratory function in non-ventilated patients with sub-acute and chronic tetraplegia. The aim of this study was to investigate the clinical feasibility of using an AFES training program to improve respiratory function and assist ventilator weaning in acute tetraplegia.

Methods

AFES was applied for between 20 and 40 minutes per day, five times per week on four alternate weeks, with 10 acute ventilator dependent tetraplegic participants. Each participant was matched retrospectively with a ventilator dependent tetraplegic control, based on injury level, age and sex. Tidal Volume (V_T) and Vital Capacity (V_C) were measured weekly, with weaning progress compared to the controls.

Results

Compliance to training sessions was 96.7%. Stimulated V_T was significantly greater than unstimulated V_T. V_T and V_C increased throughout the study, with mean V_C increasing significantly (V_T: 6.2 mL/kg to 7.8 mL/kg V_C: 12.6 mL/kg to 18.7 mL/kg). Intervention participants weaned from mechanical ventilation on average 11 (sd: ± 23) days faster than their matched controls.

Conclusion

The results of this study indicate that AFES is a clinically feasible technique for acute ventilator dependent tetraplegic patients and that this intervention may improve respiratory function and enable faster weaning from mechanical ventilation.

Trial Registration

ClinicalTrials.gov NCT02200393

Detection of the motor points of the abdominal muscles

PURPOSE

Abdominal functional electrical stimulation (AFES) is a technique intended to improve respiratory function in tetraplegia where breathing is affected due to abdominal muscle paralysis. Although it is known that optimal muscle contraction is achieved when electrical stimulation is applied close to the muscle motor point, AFES studies have used a variety of electrode positions. This study aims to investigate the feasibility of using Neuromuscular Electrical Stimulation to detect the motor points of the abdominal muscles, and to evaluate the intrasubject repeatability and intersubject uniformity of their positions, to find the most suitable AFES electrode location.

METHODS

Low frequency stimulation (0.5 Hz) was applied to the abdominal muscles of 10 able bodied and five tetraplegic participants. The electrode positions which achieved the strongest muscle contractions were recorded as the motor point positions, with measurements repeated once. For five able bodied participants, assessments were repeated after 18 months, in seated and supine positions.

RESULTS

Intersubject uniformity ranged from 2.8 to 8.8%. Motor point positions were identified with intrasubject repeatability of <1.7 cm, deemed adequate relative to standard AFES electrode size. Intrasubject repeatability shows motor point positions changed little (<1.7 cm) after 18 months but varied between seated and supine positions with repeatability of up to 3.1 cm.

CONCLUSIONS

A simple technique to locate the motor points of the abdominal muscles is presented and shown to have an adequate intrasubject repeatability, enabling the optimum AFES electrode location to be identified for each user.

Non-intrusive real-time breathing pattern detection and classification for automatic abdominal functional electrical stimulation

Abdominal Functional Electrical Stimulation (AFES) has been shown to improve the respiratory function of people with tetraplegia. The effectiveness of AFES can be enhanced by using different stimulation parameters for quiet breathing and coughing. The signal from a spirometer, coupled with a facemask, has previously been used to differentiate between these breath types. In this study, the suitability of less intrusive sensors was investigated with able-bodied volunteers. Signals from two respiratory effort belts, positioned around the chest and the abdomen, were used with a Support Vector Machine (SVM) algorithm, trained on a participant by participant basis, to classify, in real-time, respiratory activity as either quiet breathing or coughing. This was compared with the classification accuracy achieved using a spirometer signal and an SVM. The signal from the belt positioned around the chest provided an acceptable classification performance compared to the signal from a spirometer (mean cough (c) and quiet breath (q) sensitivity (Se) of Se(c)=92.9% and Se(q)=96.1% vs. Se(c)=90.7% and Se(q)=98.9%). The abdominal belt and a combination of both belt signals resulted in lower classification accuracy. We suggest that this novel SVM classification algorithm, combined with a respiratory effort belt, could be incorporated into an automatic AFES device, designed to improve the respiratory function of the tetraplegic population.

The effects of aquatic exercise on pulmonary function in patients with spinal cord injury

[Purpose] The purpose of this study was to determine the effects of aquatic exercise on pulmonary function of patients with spinal cord injury. [Subjects] The subjects were randomly allocated to an aqua group (n=10) and a land group (n=10). [Methods] Both groups trained for 60 minutes, 3 times a week for 8 weeks. Pulmonary function was assessed by measuring the forced vital capacity (FVC), forced expiratory flow rate (FER), force expiratory volume at one second (FEV1) and force expiratory volume at one second/forced vital capacity (FEV1/FVC). [Results] Following the intervention, the aqua group showed significant changes in FVC, FER, FEV1, and FEV1/FVC. The land group showed only significant differences FER. [Conclusion] The results of this study suggest the effects on the aqua group were significantly higher than those on the land group in patients with spinal cord injury.