Abdominal Functional Electrical Stimulation Research Articles

The effect of abdominal functional electrical stimulation on blood pressure in people with high level spinal cord injury.

Single centre training study. To investigate, in a group of people with spinal cord injury (SCI), the effect of transcutaneous functional electrical stimulation of the abdominal muscles (abdominal FES) during cough training on blood pressure (BP), and how it is affected by injury characteristics and alters over time. Laboratory and community. Sixteen participants with SCI (C4-T5) underwent 25 of abdominal FES cough training (5 sets of 10 stimulated coughs) over 6 weeks as part of a previously published study on the effect of abdominal FES training on cough. Systolic BP (SBP), diastolic BP (DBP) and calculated mean arterial pressure (MAP) were measured at the completion of each set. Abdominal FES coughing resulted in an average ~30% acute increase in BP from initial resting BP across all sessions in almost all participants (p < 0.001). However, the increase in BP during abdominal FES coughs from rest reduced over the 25 sessions of training by ~35% for SBP, MAP and DBP (p = 0.024, p = 0.013 and p = 0.042, respectively). There was no meaningful change in resting BP over time (p = 0.935, p = 0.705 and p = 0.988, respectively). Overall, increases in BP during abdominal FES coughs were greatest for those with chronic injuries and cervical injuries. Transcutaneous abdominal FES during cough training acutely increases BP. However, the magnitude of the increase is reduced after 25 sessions of training. Abdominal FES may offer a solution to combat orthostatic hypotension, but its effectiveness may diminish over time.

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

BackgroundChronic constipation is prevalent in people with multiple sclerosis, with current treatments usually only partially effective.ObjectivesThis 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.MethodsA 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.ResultsWhole 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.ConclusionWhile 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.

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

BackgroundFor 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.MethodsTwenty 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.ResultsFourteen 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.ConclusionsOur 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 registrationThe Australian New Zealand Clinical Trials Registry, ACTRN12617001180303. Registered 9 August 2017.

Abdominal functional electrical stimulation for bowel management in multiple sclerosis.

Aim: Functional constipation is common in multiple sclerosis (MS) and first line treatments are frequently ineffective. The current study explored the use of abdominal functional electrical stimulation (ABFES) for treating constipation in MS. Patients/methods: 20 people with MS and constipation (ROME IV criteria). The patient assessment of constipation-related quality of life questionnaire was administered at baseline and after 6 weeks of ABFES treatment alongside semi-structured interviews. Results: All patient assessment of constipation-related quality of life subscales were significant: satisfaction (p=0.003), psychosocial discomfort (p=0.008), physical discomfort (p=0.001) and worries and concerns (p=0.003). A long-term therapeutic effect, reduction in laxative use and improved sexual functioning were also reported. Conclusion: ABFES provides a potential alternative treatment intervention for people with MS and constipation.

Abdominal Functional Electrical Stimulation to Augment Respiratory Function in Spinal Cord Injury.

Background: Functional electrical stimulation (FES) is the application of electrical pulses to a nerve to achieve a functional muscle contraction. Surface electrical stimulation of the nerves that innervate the abdominal muscles, termed abdominal FES, can cause the abdominal muscles to contract, even when paralysed after spinal cord injury. As the abdominal muscles are the major expiratory muscles, and commonly partially or completely paralysed in tetraplegia, abdominal FES offers a promising method of improving respiratory function for this patient group. Objective: The aim of the article is to provide readers with a better understanding of how abdominal FES can be used to improve the health of the spinal cord-injured population. Methods: A narrative review of the abdominal FES literature was performed. Results: Abdominal FES can achieve an immediate effective cough in patients with tetraplegia, while the repeated application over 6 weeks of abdominal FES can improve unassisted respiratory function. Ventilator duration and tracheostomy cannulation time can also be reduced with repeated abdominal FES. Conclusion: Abdominal FES is a noninvasive method to achieve functional improvements in cough and respiratory function in acute and chronically injured people with tetraplegia. Potential practical outcomes of this include reduced ventilation duration, assisted tracheostomy decannulation, and a reduction in respiratory complications. All of these outcomes can contribute to reduced morbidity and mortality, improved quality of life, and significant potential cost savings for local health care providers.

Using a Sniff Controller to Self-Trigger Abdominal Functional Electrical Stimulation for Assisted Coughing Following Cervical Spinal Cord Lesions.

Individuals with cervical spinal cord lesions (SCLs) typically depend on caregivers to manually assist in coughing by pressing against their abdominal wall. Coughing can also be assisted by functional electric stimulation (FES) applied to abdominal muscles via surface electrodes. Efficacy of FES, however, depends on precise temporal synchronization. The sniff controller is a trigger that enables paralyzed individuals to precisely control external devices through alterations in nasal airflow. We hypothesized that FES self-triggering by sniff controller may allow for effective cough timing. After optimizing parameters in 16 able-bodied subjects, we measured peak expiratory flow (PEF) in 14 subjects with SCL who coughed with or without assistance. Assistance was either manual assistance of a caregiver, caregiver activated FES, button self-activated FES (for SCL participants who could press a button), or sniff-controlled self-activated FES. We found that all assisted methods provided equally effective improvements, increasing PEF on average by 25 ± 27% (F[4,52] = 7.99, p = 0.00004 ). There was no difference in efficacy between methods of assistance ( F[3,39] = 0.41, p = 0.75 ). Notably, sniff-controlled FES was the only method of those tested that can be activated by all paralyzed patients alone. This provides for added independence that is a critical factor in quality of life following SCL.

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

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. A systematic search was performed on PubMed, with studies included if they applied abdominal FES to improve respiratory function in patients with SCI. 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. 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 improve respiratory function after spinal cord injury: a systematic review and meta-analysis.

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

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.

Detection of the motor points of the abdominal muscles.

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. 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. 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. 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 Sec=92.9% and Seq=96.1% vs. Sec=90.7% and Seq=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.

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

ObjectiveTo demonstrate the effect of a passive abdominal functional electrical stimulation (AFES) training program on unassisted respiratory measures in tetraplegia.DesignLongitudinal feasibility study.SettingNational spinal injuries unit in a university teaching hospital.ParticipantsTwelve patients with tetraplegic spinal cord injury, who could breathe independently, with reduced vital capacity and no visible abdominal movement.InterventionThree weeks of abdominal muscle conditioning using transcutaneous AFES.Main outcome measuresForced vital capacity (FVC), forced exhaled volume in 1 second (FEV1), peak expiratory flow rate (PEF), and maximum exhaled pressure (MEP).ResultsMean (SD) FVC increased by 0.36 l (0.23) during training (P = 0.0027). Mean (SD) FEV1 and PEF tended to increase by 0.18 l (0.16) and 0.39 l/seconds (0.35), respectively, but this was not significant. No significant change was found in the outcome measures during a 1-week pre-training control phase and during a 3-week post-training phase.ConclusionsThe increase in FVC over the training period and the absence of change before or after training suggest that passive abdominal FES training can be used for respiratory rehabilitation in tetraplegia.

Automatic electrical stimulation of abdominal wall muscles increases tidal volume and cough peak flow in tetraplegia

Paralysis of the respiratory muscles in people with tetraplegia affects their ability to breathe and contributes to respiratory complications. Surface functional electrical stimulation (FES) of abdominal wall muscles can be used to increase tidal volume (V_{T}) and improve cough peak flow (CPF) in tetraplegic subjects who are able to breathe spontaneously. This study aims to evaluate the feasibility and effectiveness of a novel abdominal FES system which generates stimulation automatically, synchronised with the subjects' voluntary breathing activity. Four subjects with complete tetraplegia (C4-C6), breathing spontaneously, were recruited. The automatic stimulation system ensured that consistent stimulation was achieved. We compared spirometry during unassisted and FES-assisted quiet breathing and coughing, and measured the effect of stimulation on end-tidal CO_2 (EtCO_2) during quiet breathing. The system dependably recognised spontaneous respiratory effort, stimulating appropriately, and was well tolerated by patients. Significant increases in V_T during quiet breathing (range 0.05-0.23 L) and in CPF (range 0.04-0.49 L/s) were observed. Respiratory rate during quiet breathing decreased in all subjects when stimulated, whereas minute ventilation increased by 1.05-2.07 L/min. The changes in EtCO_2 were inconclusive. The automatic stimulation system augmented spontaneous breathing and coughing in tetraplegic patients and may provide a potential means of respiratory support for tetraplegic patients with reduced respiratory capacity.

Electromyographic signal-activated functional electrical stimulation of abdominal muscles: the effect on pulmonary function in patients with tetraplegia

Paralysis of abdominal muscles is the main cause of respiratory dysfunctions in patients with lower cervical spinal cord lesion. Activation of the abdominal muscles using functional electrical stimulation (FES) improved respiratory function in these patients. But application of FES frequently requires a caregiver, and it may not be well synchronized with the patient's respiratory activity. To perform preliminary examination of electromyographic (EMG)-activated FES for caregiver-independent and synchronized cough and expiration induction in tetraplegia. Self-controlled study. Loewenstein Rehabilitation Center, Raanana, Israel. A total of 10 male patients with complete or almost complete tetraplegia. Peak expiratory flow (PEF), forced vital capacity (FVC), and maximal voluntary ventilation (MVV). The outcome measures were examined with the abdominal muscles unassisted or assisted by various methods. These included manual assistance or application of FES, activated by a caregiver, by the patient, or by EMG signals elicited from the patient's muscle. Manual assistance improved the mean PEF value by 36.7% (P<0.01) and the mean FVC value by 15.4% (P=0.01). FES did not significantly change most measurements, and patient-activated FES even reduced PEF (P<0.05). But following EMG-activated FES PEF and FVC values were higher than those following patient-activated FES (P<0.05 for PEF; P<0.01 for FVC), and their mean values were higher by 15.8 and 18.9%, respectively. Abdominal FES failed to improve respiratory function in this study, but applying FES to abdominal muscles by EMG from the patient's muscle may promote caregiver-free respiration and coughing in persons with cervical SCL.

Breathing Induced by Abdominal Muscle Stimulation in Individuals Without Spontaneous Ventilation

The purpose of the study was to determine if functional electrical stimulation of abdominal muscles (FESAM) could maintain pulmonary ventilation at acceptable levels in individuals with spinal cord injury (SCI) who are unable to breathe spontaneously. This is the first published investigation of this technique in this subject population. This case series study included three individuals with SCI; two were on mechanical ventilation (MV), and one used mechanical ventilation and also had an implanted phrenic nerve stimulator (PNS). Using surface electrodes, stimulation was applied to the rectus abdominis and lateral group of abdominal muscles. Repetitive trains of pulses produced a breathing frequency of 20 breaths/min. The longest periods of breathing using only FESAM-supported ventilation for the three subjects were 30, 40, and 210 s, respectively. Airflow at the mouth and volumes were measured with a pneumotachograph and/or optoelectronic plethysmography. Oxygenation was monitored with a pulse oximeter. The tidal volumes generated exclusively by FESAM were sufficient to maintain adequate oxygenation during the periods of stimulation. When oxygenation measured with pulse oximetry dropped to 92% saturation, FESAM was discontinued, and MV or PNS was resumed. This is the first report of achieving successful ventilation in individuals with SCI who have zero tidal volume using FESAM. These preliminary results indicate the clinical potential of FESAM as an additional tool in the armamentarium of supported ventilation.

Functional electrical stimulation of abdominal muscles to augment tidal volume in spinal cord injury.

Functional electrical stimulation (FES) of abdominal muscles as a method of enhancing ventilation was explored in six neurologically intact subjects and five subjects with spinal cord injury (SCI) who had levels of injury between C4 and C7. Pulmonary ventilation was augmented in both groups predominantly due to an increase in tidal volume. The average increase in tidal volume during FES for the neurologically intact group was 350 ml, while in the SCI group it was 220 ml. The FES caused active volume decreases in both the lower thorax and upper abdomen, which together appear to be the mechanism behind the increases seen in tidal volume. Therefore, the proposed method might be useful in future clinical practice. The results indicate that FES of abdominal muscles should be more thoroughly explored as a potential technique of ventilatory support in SCI. The results also point to the necessity for further studies of maintaining the condition of the chest wall in the pulmonary rehabilitation of individuals with tetraplegia.

Functional Electrical Stimulation to Enhance Cough in Quadriplegia

Respiratory problems are a major cause of death in the acute and chronic phases of cervical spinal cord injury (CSCI); CSCI paralyzes the intercostal and abdominal muscles, reducing ability to cough and clear secretions. Impaired cough due to neuromuscular disorders can be assessed with the maximum expiratory pressure (MEP). This study consists of two experiments with CSCI patients. In the first, MEP measurements were recorded with the following maneuvers performed: (1) spontaneous cough attempts, (2) manually assisted cough, and (3) cough attempts with functional electrical stimulation (FES) applied to the abdominal wall. In the second, spontaneous cough attempts and cough attempts with a portable FES unit were recorded. These CSCI patients were found to have a greatly reduced MEP when they coughed spontaneously. Either FES-assisted or manually assisted coughing increased the MEP in all patients studied. By increasing the MEP, abdominal muscle FES could enhance cough in quadriplegics.