Functional electrical stimulation to enhance cough in quadriplegia

A preliminary study on the feasibility of community game-based respiratory muscle training for individuals with high cervical spinal cord injury levels: a novel approach

Background

Respiratory disorders result in rehospitalization and premature death of patients with cervical spinal cord injuries (CSCI). Community game-based respiratory muscle training (RMT) programs could reduce secondary complications.

Methods

We examined the feasibility and preliminary efficacy of RMT as a community-based exercise program. Among the 10 included participants (eight male and two female), four, one, one, and four reported C3, C4, C5, and C6 complete injuries, respectively (eight graded by American Spinal Injury Association impairment scale [ASIA] A and two by ASIA B). Their mean age was 43 ± 12.3 y. The time since injury was 10 ± 6.7 y. The participants completed an RMT program for 60 min/day, twice weekly, for 8 weeks. The participants were trained in the use of a newly developed game-based RMT device. The device provides consistent pressure for respiratory muscle strength and endurance training. Seven RMT devices were modified to allow 10 game-based RMT programs. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), peak expiratory flow (PEF), vital capacity (VC), inspiratory capacity (IC), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), and peak cough flow (PCF) were measured.

Results

There were improvements after RMT compared to pre-RMT in FVC (p = 0.027, 10.62%, 0.22 effect size [ES]), PEF (p = 0.006, 23.21%, 0.45 ES), VC (p = 0.002, 35.52%, 0.60 ES), IC (p = 0.001, 46.94%, 0.81 ES), IRV (p = 0.001, 90.53%, 1.22 ES), MIP (p = 0.002, 97.25%, 1.32 ES), MEP (p = 0.005, 141.12%, 1.07 ES), and PCF (p = 0.001, 35.60%, 0.74 ES). The participants reported a positive impact of the program.

Conclusions

Community game-based RMT for individuals with CSCI appears to be safe and feasible. Community exercise with RMT use may have a positive impact on the respiratory measures for patients with CSCI who are vulnerable to respiratory compromise.

Trial registration

KCT0005980.

Effects of trunk muscle activation on trunk stability, arm power, blood pressure and performance in wheelchair rugby players with a spinal cord injury

Objective: In wheelchair rugby (WR) athletes with tetraplegia, wheelchair performance may be impaired due to (partial) loss of innervation of upper extremity and trunk muscles, and low blood pressure (BP). The objective was to assess the effects of electrical stimulation (ES)-induced co-contraction of trunk muscles on trunk stability, arm force/power, BP, and WR performance.Design: Cross-sectional study.Setting: Rehabilitation research laboratory and WR court.Participants: Eleven WR athletes with tetraplegia.Interventions: ES was applied to the rectus abdominis, obliquus externus abdominis and erector spinae muscles. For every test, the ES condition was compared to the non-ES condition.Outcome measures: Stability was assessed with reaching tasks, arm force/power with an isokinetic test on a dynamometer, BP during an ES protocol and WR skill performance with the USA Wheelchair Rugby Skill Assessment.Results: Overall reaching distance (ES 14.6 ± 7.5 cm, non-ES 13.4 ± 8.2 cm), and BP showed a significant increase with ES. Arm force (ES 154 ± 106 N, non-ES 148 ± 102 N) and power (ES 37 ± 26 W, non-ES 36 ± 25 W), and WR skills were not significantly improved.Conclusion: ES-induced trunk muscle activation positively affects trunk stability and BP, but not arm force/power. No effects were found in WR skill performance, probably due to abdominal strapping. More research is needed to assess different ES (training) protocols and longitudinal effects.

Development and pilot testing of novel game-based respiratory rehabilitation exercise devices for patients with tetraplegia

BACKGROUND:

Individuals with spinal cord injuries (SCI) show restricted breathing patterns with reduced lung volumes and capacities.

OBJECTIVE:

To improve breathing in such individuals, we aimed to develop breathing exercise devices using a user-centered design (UCD) and then assess the effects of these devices on breathing.

METHODS:

Patients with SCI were involved in the device development. Preliminary online survey participants were recruited from the community, and interview and pilot test participants were recruited from a patient self-help group. The four UCD phases were repeatedly performed. Users required fun, easy, multi-player, and safe exercise devices.

RESULTS:

Seven breathing exercise devices were developed, and 10 different game-based exercises were performed. Two individuals participated in a pilot test involving a respiratory rehabilitation exercise program conducted twice weekly for 60 min/session over 8 weeks. Lung function was assessed using a spirometer. Forced vital capacity, forced expiratory volume in 1 s, and vital capacity showed minimal changes, whereas maximum inspiratory and expiratory pressures improved. Participants reported that the exercises were entertaining and that the competitive nature of the game-like exercises encouraged further participation.

CONCLUSION:

Breathing exercise programs using our developed devices can improve breathing and positively affect the psychological states and sociability of users.

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.

Potential of electric stimulation for the management of COVID-19

The COVID-19 pandemic is the most devastating health emergency that humans have seen over the past century. The war against the disease has been handicapped by unavailability of effective therapeutic options. Till date, there is no clinically approved vaccine or drug for the treatment of COVID-19, and the ongoing search to find a novel therapy is progressing at pandemic pace. Herein, we propose a novel hypothesis based on sound research evidence that electric stimulation can be a potential adjuvant to the currently used symptomatic therapies and antiviral drugs. Based on preclinical evidence, we propose that electric stimulation can improve respiratory functions, inhibit SARS-CoV-2 growth, reduce pain, boost immunity and improve the penetration of antiviral drugs. We envisage that our hypothesis, if used clinically as an adjuvant, may significantly improve the therapeutic outcomes of the current treatment regimen being used around the globe for the management of COVID-19.

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.

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.

Review of Epidural Spinal Cord Stimulation for Augmenting Cough after Spinal Cord Injury

Spinal cord injury (SCI) remains a debilitating condition for which there is no cure. In addition to loss of somatic sensorimotor functions, SCI is also commonly associated with impairment of autonomic function. Importantly, cough dysfunction due to paralysis of expiratory muscles in combination with respiratory insufficiency can render affected individuals vulnerable to respiratory morbidity. Failure to clear sputum can aggravate both risk for and severity of respiratory infections, accounting for frequent hospitalizations and even mortality. Recently, epidural stimulation of the lower thoracic spinal cord has been investigated as novel means for restoring cough by evoking expiratory muscle contraction to generate large positive airway pressures and expulsive air flow. This review article discusses available preclinical and clinical evidence, current challenges and clinical potential of lower thoracic spinal cord stimulation (SCS) for restoring cough in individuals with SCI.

Respiratory flow and vital signs associated with the intensity of functional electrical stimulation delivered to human abdominal muscles during quiet breathing

[Purpose] The purpose of this study was to examine the effects of increasing the intensity of functional electrical stimulation delivered to abdominal muscles during quiet breathing on respiratory flow, vital signs and pain in healthy subjects. [Subjects and Methods] Electrical stimulation was delivered bilaterally using one pair of high-conductivity gel-skin plate electrodes, placed on both sides of the abdomen, to nine healthy males. Subjects were required to breathe normally through a face mask for 2 minutes while in a supine position. The stimulation intensity was incrementally increased by 10 mA until reaching 100 mA. Respiratory parameters, vital signs and pain based on the visual analog scale were measured for each intensity of electrical stimulation. [Results] Transcutaneous oxygen saturation showed a slight upward trend in association with increasing stimulation intensity, but there were no significant changes in pulse or blood pressure. Respiratory flow, tidal volume, and minute ventilation increased significantly as the stimulation intensity rose. [Conclusion] This study revealed that functional electrical stimulation can be safely delivered to human abdominal muscles without causing vital sign abnormalities. It was also found that the appropriate intensity level of electrical stimulation for achieving effects on respiratory flow while also minimizing pain is 60–80 mA.

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.

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.

Benefits of interventions for respiratory secretion management in adult palliative care patients-a systematic review

BACKGROUND

Respiratory secretions impact negatively on palliative patients. Unfortunately, a gold standard therapy is not yet available. The purpose of this study was to identify which interventions are in use to control respiratory secretions in patients with chronic disease with a poor prognosis and verify their effects on outcomes relevant for palliative care patients.

METHODS

A systematic review of the literature with narrative summary was conducted. We searched eight electronic databases in April (6th), 2016. Citation-tracking and reference list searches were conducted. We included randomized controlled trials, crossover trials, observational and qualitative studies regarding interventions for respiratory secretion management in adult patients with chronic diseases that met inclusion criteria indicating short prognosis.

RESULTS

Six randomized controlled trials, 11 observational studies, ten crossover trials and one qualitative study were found. Interventions included mechanical insufflation-exsufflation (MIE), expiratory muscle training, manually-assisted cough, tracheotomy, chest physiotherapy, suctioning, air stacking, electrical stimulation of abdominal muscles, nebulized saline, positive expiratory pressure masks, percussive ventilation, high frequency chest wall oscillations. The interventions with most promising benefits to patients in palliative care were manually-assisted cough and mechanical insufflation-exsufflation to promote expectoration and percussive ventilation to improve mucous clearance.

CONCLUSION

Therapies, such as manually assisted cough, mechanical insufflation-exsufflation and percussive ventilation, which aim to deal with respiratory secretion, were the most promising treatment for use in palliative care for specific diseases. Nevertheless, the evidence still needs to improve in order to identify which treatment is the best.

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.

Electrical Stimulation and Motor Recovery

In recent years, several investigators have successfully regenerated axons in animal spinal cords without locomotor recovery. One explanation is that the animals were not trained to use the regenerated connections. Intensive locomotor training improves walking recovery after spinal cord injury (SCI) in people, and >90% of people with incomplete SCI recover walking with training. Although the optimal timing, duration, intensity, and type of locomotor training are still controversial, many investigators have reported beneficial effects of training on locomotor function. The mechanisms by which training improves recovery are not clear, but an attractive theory is available. In 1949, Donald Hebb proposed a famous rule that has been paraphrased as “neurons that fire together, wire together.” This rule provided a theoretical basis for a widely accepted theory that homosynaptic and heterosynaptic activity facilitate synaptic formation and consolidation. In addition, the lumbar spinal cord has a locomotor center, called the central pattern generator (CPG), which can be activated nonspecifically with electrical stimulation or neurotransmitters to produce walking. The CPG is an obvious target to reconnect after SCI. Stimulating motor cortex, spinal cord, or peripheral nerves can modulate lumbar spinal cord excitability. Motor cortex stimulation causes long-term changes in spinal reflexes and synapses, increases sprouting of the corticospinal tract, and restores skilled forelimb function in rats. Long used to treat chronic pain, motor cortex stimuli modify lumbar spinal network excitability and improve lower extremity motor scores in humans. Similarly, epidural spinal cord stimulation has long been used to treat pain and spasticity. Subthreshold epidural stimulation reduces the threshold for locomotor activity. In 2011, Harkema et al. reported lumbosacral epidural stimulation restores motor control in chronic motor complete patients. Peripheral nerve or functional electrical stimulation (FES) has long been used to activate sacral nerves to treat bladder and pelvic dysfunction and to augment motor function. In theory, FES should facilitate synaptic formation and motor recovery after regenerative therapies. Upcoming clinical trials provide unique opportunities to test the theory.

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

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.

Respiratory motor control disrupted by spinal cord injury: mechanisms, evaluation, and restoration

Pulmonary complications associated with persistent respiratory muscle weakness, paralysis, and spasticity are among the most important problems faced by patients with spinal cord injury when lack of muscle strength and disorganization of reciprocal respiratory muscle control lead to breathing insufficiency. This review describes the mechanisms of the respiratory motor control and its change in individuals with spinal cord injury, methods by which respiratory function is measured, and rehabilitative treatment used to restore respiratory function in those who have experienced such injury.

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.

Esophageal Considerations After Spinal Cord Injury

Speech-Language Pathologists (SLPs) are frequently involved with patients after spinal cord injury due to the frequency of speech and swallowing problems. Any stage of swallowing can be adversely affected, and it is imperative that the SLP be aware that spinal cord injuries at various levels can produce a variety of deficits affecting oropharyngeal, esophageal, and many other functions. The SLP has a role in assessment and treatment of oropharyngeal dysphagia and also in recognizing how and when this injury should lead to screening and referral for disorders in the esophageal stage.

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 ( Pga) of 40 cm H2O at functional residual capacity. Results. In the MEP effort, stimulation increased the maximal Pga (from 21.4 ± 7.0 to 59.0 ± 5.7 cm H2O) and esophageal pressure ( Pes; 47.2 ± 11.7 to 65.6 ± 13.6 cm H2O). During the cough efforts, stimulation increased Pga (19.5 ± 6.0 to 57.9 ± 7.0 cm H2O) and Pes (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 Pga 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.

Physiotherapy secretion removal techniques in people with spinal cord injury: a systematic review

OBJECTIVE

To address whether secretion removal techniques increase airway clearance in people with chronic spinal cord injury (SCI).

DATA SOURCES AND STUDY SELECTION

MEDLINE/PubMed, CINAHL, EMBASE, and PsycINFO were searched from inception to May 2009 for population keywords (spinal cord injury, paraplegia, tetraplegia, quadriplegia) paired with secretion removal-related interventions and outcomes. Inclusion criteria for articles were a research study, irrespective of design, that examined secretion removal in people with chronic SCI published in English.

REVIEW METHODS

Two reviewers determined whether articles met the inclusion criteria, abstracted information, and performed a quality assessment using PEDro or Downs and Black criteria. Studies were then given a level of evidence based on a modified Sackett scale.

RESULTS

Of 2416 abstracts and titles retrieved, 24 met the inclusion criteria. Subjects were young (mean, 31 years) and 84% were male. Most evidence was level 4 or 5 and only 2 studies were randomized controlled trials. Three reports described outcomes for secretion removal techniques in addition to cough, whereas most articles examined the immediate effects of various components of cough. Studies examining insufflation combined with manual assisted cough provided the most consistent, high-level evidence. Compelling recent evidence supports the use of respiratory muscle training or electrical stimulation of the expiratory muscles to facilitate airway clearance in people with SCI.

CONCLUSION

Evidence supporting the use of secretion removal techniques in SCI, while positive, is limited and mostly of low level. Treatments that increase respiratory muscle force show promise as effective airway clearance techniques.

Cough following low thoracic hemisection in the cat

A function of the abdominal expiratory muscles is the generation of cough, a critical respiratory defense mechanism that is often disrupted following spinal cord injury. We assessed the effects of a lateral T9/10 hemisection on cough production at 4, 13 and 21 weeks post-injury in cats receiving extensive locomotor training. The magnitudes of esophageal pressure as well as of bilateral rectus abdominis electromyogram activity during cough were not significantly different from pre-injury values at all time points evaluated. The results show that despite considerable interruption of the descending pre-motor drive from the brainstem to the expiratory motoneuron pools, the cough motor system shows a significant function by 4 weeks following incomplete thoracic injury.

Lower thoracic spinal cord stimulation to restore cough in patients with spinal cord injury: results of a National Institutes of Health-sponsored clinical trial. Part I: methodology and effectiveness of expiratory muscle activation

OBJECTIVE

Evaluation of the capacity of lower thoracic spinal cord stimulation (SCS) to activate the expiratory muscles and generate large airway pressures and high peak airflows characteristic of cough, in subjects with tetraplegia.

DESIGN

Clinical trial.

SETTING

Inpatient hospital setting for electrode insertion; outpatient setting for measurement of respiratory pressures; home setting for application of SCS.

PARTICIPANTS

Subjects (N=9; 8 men, 1 woman) with cervical spinal cord injury and weak cough.

INTERVENTIONS

A fully implantable electrical stimulation system was surgically placed in each subject. Partial hemilaminectomies were made to place single-disk electrodes in the epidural space at the T9, T11, and L1 spinal levels. A radiofrequency receiver was placed in a subcutaneous pocket over the anterior portion of the chest wall. Electrode wires were tunneled subcutaneously and connected to the receiver. Stimulation was applied by activating a small portable external stimulus controller box powered by a rechargeable battery to each electrode lead alone and in combination.

MAIN OUTCOME MEASURES

Peak airflow and airway pressure generation achieved with SCS.

RESULTS

Supramaximal SCS resulted in high peak airflow rates and large airway pressures during stimulation at each electrode lead. Maximum peak airflow rates and airway pressures were achieved with combined stimulation of any 2 leads. At total lung capacity, mean maximum peak airflow rates and airway pressure generation were 8.6+/-1.8 (mean +/- SE) L/s and 137+/-30 cmH2O (mean +/- SE), respectively.

CONCLUSIONS

Lower thoracic SCS results in near maximum activation of the expiratory muscles and the generation of high peak airflow rates and positive airway pressures in the range of those observed with maximum cough efforts in healthy persons.

Pulmonary function and spinal cord injury

Injury to the cervical and upper thoracic spinal cord disrupts function of inspiratory and expiratory muscles, as reflected by reduction in spirometric and lung volume parameters and static mouth pressures. In association, subjects with tetraplegia have decreased chest wall and lung compliance, increased abdominal wall compliance, and rib cage stiffness with paradoxical chest wall movements, all of which contribute to an increase in the work of breathing. Expiratory muscle function is more compromised than inspiratory muscle function among subjects with tetraplegia and high paraplegia, which can result in ineffective cough and propensity to mucus retention and atelectasis. Subjects with tetraplegia also demonstrate heightened vagal activity with reduction in baseline airway caliber, findings attributed to loss of sympathetic innervation to the lungs. Significant increase in airway caliber following inhalation of ipratropium bromide, an anticholinergic agent, suggests that reduction in airway caliber is not due to acquired airway fibrosis stemming from repeated infections or to abnormal hysteresis secondary to chronic inability of subjects to inhale to predicted total lung capacity. Reduced baseline airway caliber possibly explains why subjects with tetraplegia exhibit airway hyperresponsiveness to methacholine and ultrasonically nebulized distilled water. While it has been well demonstrated that bilateral phrenic nerve pacing or stimulation through intramuscular diaphragmatic electrodes improves inspiratory muscle function, it remains unclear if inspiratory muscle training improves pulmonary function. Recent findings suggest that expiratory muscle training, electrical stimulation of expiratory muscles and administration of a long-acting beta(2)-agonist (salmeterol) improve physiological parameters and cough. It is unknown if baseline bronchoconstriction in tetraplegia contributes to respiratory symptoms, of if the chronic administration of a bronchodilator reduces the work of breathing and/or improves respiratory symptoms. Less is known regarding the benefits of treatment of obstructive sleep apnea, despite evidence indicating that the prevalence of this condition in persons with tetraplegia is far greater than that encountered in able-bodied individuals.

Surface functional electrical stimulation of the abdominal muscles to enhance cough and assist tracheostomy decannulation after high-level spinal cord injury

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.

Improving respiration in patients with tetraplegia by functional electrical stimulation: an anatomical perspective

Patients with tetraplegia often have respiratory complications because of paralysis of the abdominal and intercostal muscles. Functional electrical stimulation (FES) has been used to improve breathing in these patients by applying surface stimulation to the abdominal muscles. We aimed to find the best nerves to stimulate directly to increase tidal volume and make cough more effective. Surface electrodes were placed on a patient's abdominal wall to find the optimum points for surface stimulation. These positions were plotted on a transparent sheet. The abdomino-intercostal nerves were dissected in five male dissecting room cadavers matched for size with the patient. The plastic sheet was then superimposed over each of the dissections to clarify the relationship between optimum surface stimulation points and the underlying nerves. Results show that the optimum surface stimulation points overlie the course of abdomino-intercostal nerves T9, 10, and 11. The success with selecting stimulation points associated with T9, 10, and 11 is probably because of the large mass of abdominal muscle supplied by these nerves. The constant position of the nerves below the ribs makes the intercostal space a possible site for direct stimulation of the abdomino-intercostal nerves.

Effect of spinal cord injury on the respiratory system: basic research and current clinical treatment options

Spinal cord injury (SCI) often leads to an impairment of the respiratory system. The more rostral the level of injury, the more likely the injury will affect ventilation. In fact, respiratory insufficiency is the number one cause of mortality and morbidity after SCI. This review highlights the progress that has been made in basic and clinical research, while noting the gaps in our knowledge. Basic research has focused on a hemisection injury model to examine methods aimed at improving respiratory function after SCI, but contusion injury models have also been used. Increasing synaptic plasticity, strengthening spared axonal pathways, and the disinhibition of phrenic motor neurons all result in the activation of a latent respiratory motor pathway that restores function to a previously paralyzed hemidiaphragm in animal models. Human clinical studies have revealed that respiratory function is negatively impacted by SCI. Respiratory muscle training regimens may improve inspiratory function after SCI, but more thorough and carefully designed studies are needed to adequately address this issue. Phrenic nerve and diaphragm pacing are options available to wean patients from standard mechanical ventilation. The techniques aimed at improving respiratory function in humans with SCI have both pros and cons, but having more options available to the clinician allows for more individualized treatment, resulting in better patient care. Despite significant progress in both basic and clinical research, there is still a significant gap in our understanding of the effect of SCI on the respiratory system.

Functional electrical stimulation after spinal cord injury: current use, therapeutic effects and future directions

Repair of the injured spinal cord by regeneration therapy remains an elusive goal. In contrast, progress in medical care and rehabilitation has resulted in improved health and function of persons with spinal cord injury (SCI). In the absence of a cure, raising the level of achievable function in mobility and self-care will first and foremost depend on creative use of the rapidly advancing technology that has been so widely applied in our society. Building on achievements in microelectronics, microprocessing and neuroscience, rehabilitation medicine scientists have succeeded in developing functional electrical stimulation (FES) systems that enable certain individuals with SCI to use their paralyzed hands, arms, trunk, legs and diaphragm for functional purposes and gain a degree of control over bladder and bowel evacuation. This review presents an overview of the progress made, describes the current challenges and suggests ways to improve further FES systems and make these more widely available.

A control system for automatic electrical stimulation of abdominal muscles to assist respiratory function in tetraplegia

People with tetraplegia have poor respiratory function leading to limited tidal volume (V(T)) and reduced cough peak flow (CPF). These problems may cause respiratory failure during the initial admission or subsequent intercurrent illness. Electrical stimulation of the abdominal muscles during expiration can improve respiratory function by increasing V(T) and CPF. We developed a novel control system to automatically trigger muscle stimulation, synchronised with the subject's voluntary respiratory activity. The system was tested in four subjects with a functionally complete lesion at level C4 to C6, aged between 16 and 46 years, 3 months to 5 years post injury, who were breathing spontaneously. The algorithm delivered automatic stimulation patterns, detecting cough and quiet breathing while suppressing stimulation during other activities such as speaking. Marked increases in V(T) (between 9% and 71% of baseline) and CPF (between 31% and 54% of baseline) were observed, suggesting that the technique may have potential use in both acute and established tetraplegia to increase minute ventilation and to improve cough clearance of secretions.

Optimal electrode placement for noninvasive electrical stimulation of human abdominal muscles

Abdominal muscles are the most important expiratory muscles for coughing. Spinal cord-injured patients have respiratory complications because of abdominal muscle weakness and paralysis and impaired ability to cough. We aimed to determine the optimal positioning of stimulating electrodes on the trunk for the noninvasive electrical activation of the abdominal muscles. In six healthy subjects, we compared twitch pressures produced by a single electrical pulse through surface electrodes placed either posterolaterally or anteriorly on the trunk with twitch pressures produced by magnetic stimulation of nerve roots at the T10level. A gastroesophageal catheter measured gastric pressure (Pga) and esophageal pressure (Pes). Twitches were recorded at increasing stimulus intensities at functional residual capacity (FRC) in the seated posture. The maximal intensity used was also delivered at total lung capacity (TLC). At FRC, twitch pressures were greatest with electrical stimulation posterolaterally and magnetic stimulation at T10and smallest at the anterior site (Pga, 30 ± 3 and 33 ± 6 cmH2O vs. 12 ± 3 cmH2O; Pes 8 ± 2 and 11 ± 3 cmH2O vs. 5 ± 1 cmH2O; means ± SE). At TLC, twitch pressures were larger. The values for posterolateral electrical stimulation were comparable to those evoked by thoracic magnetic stimulation. The posterolateral stimulation site is the optimal site for generating gastric and esophageal twitch pressures with electrical stimulation.

Changes in expiratory muscle function following spinal cord section

Following spinal cord injury, muscles below the level of injury develop variable degrees of disuse atrophy. The present study assessed the physiological changes of the expiratory muscles in a cat model of spinal cord injury. Muscle fiber typing, cross-sectional area, muscle weight, and changes in pressure-generating capacity were assessed in five cats spinalized at the T6level. Airway pressure (P)-generating capacity was monitored during lower thoracic spinal cord stimulation before and 6 mo after spinalization. These parameters were also assessed in five acute animals, which served as controls. In spinalized animals, P fell from 41 ± l to 28 ± 3 cmH2O (means ± SE; P < 0.001). Muscle weight of the external oblique, internal oblique, transversus abdominis, and internal intercostal muscles decreased significantly ( P < 0.05 for each). Muscle weight of the external oblique, internal oblique, transversus abdominis, and internal intercostal, but not rectus abdominis (RA), correlated linearly with P ( r > 0.7 for each; P < 0.05 for each). Mean muscle fiber cross-sectional area of these muscles was significantly smaller ( P < 0.05 for each; except RA) and also correlated linearly with P ( r > 0.55 for each; P < 0.05 for each, except RA). In spinalized animals, the expiratory muscles demonstrated a significant increase in the population of fast muscle fibers. These results indicate that, following spinalization, 1) the expiratory muscles undergo significant atrophy and fiber-type transformation and 2) the P-generating capacity of the expiratory muscles falls significantly secondary to reductions in muscle mass.

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

BACKGROUND

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.

OBJECTIVE

To perform preliminary examination of electromyographic (EMG)-activated FES for caregiver-independent and synchronized cough and expiration induction in tetraplegia.

DESIGN

Self-controlled study.

SETTING

Loewenstein Rehabilitation Center, Raanana, Israel.

SUBJECTS

A total of 10 male patients with complete or almost complete tetraplegia.

MAIN OUTCOME MEASURES

Peak expiratory flow (PEF), forced vital capacity (FVC), and maximal voluntary ventilation (MVV).

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Effect of spinal cord injury on the respiratory system: basic research and current clinical treatment options

Spinal cord injury (SCI) often leads to an impairment of the respiratory system. The more rostral the level of injury, the more likely the injury will affect ventilation. In fact, respiratory insufficiency is the number one cause of mortality and morbidity after SCI. This review highlights the progress that has been made in basic and clinical research, while noting the gaps in our knowledge. Basic research has focused on a hemisection injury model to examine methods aimed at improving respiratory function after SCI, but contusion injury models have also been used. Increasing synaptic plasticity, strengthening spared axonal pathways, and the disinhibition of phrenic motor neurons all result in the activation of a latent respiratory motor pathway that restores function to a previously paralyzed hemidiaphragm in animal models. Human clinical studies have revealed that respiratory function is negatively impacted by SCI. Respiratory muscle training regimens may improve inspiratory function after SCI, but more thorough and carefully designed studies are needed to adequately address this issue. Phrenic nerve and diaphragm pacing are options available to wean patients from standard mechanical ventilation. The techniques aimed at improving respiratory function in humans with SCI have both pros and cons, but having more options available to the clinician allows for more individualized treatment, resulting in better patient care. Despite significant progress in both basic and clinical research, there is still a significant gap in our understanding of the effect of SCI on the respiratory system.

Respiratory muscle strength and cough capacity in patients with Duchenne muscular dystrophy

The function of inspiratory muscles is crucial for effective cough as well as expiratory muscles in patients with Duchenne muscular dystrophy (DMD). However, there is no report on the correlation between cough and inspiratory muscle strength. To investigate the relationships of voluntary cough capacity, assisted cough techniques, and inspiratory muscle strength as well as expiratory muscle strength in patients with DMD (n= 32). The vital capacity (VC), maximum insufflation capacity (MIC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) were measured. Unassisted peak cough flow (UPCF) and three different techniques of assisted PCF were evaluated. The mean value of MICs (1918 +/- 586 mL) was higher than that of VCs (1474 +/- 632 mL) (p < 0.001). All three assisted cough methods showed significantly higher value than unassisted method (212 +/- 52 L/min) (F = 66.13, p < 0.001). Combined assisted cough technique (both manual and volume assisted PCF; 286 +/- 41 L/min) significantly exceeded manual assisted PCF (MPCF; 246 +/- 49 L/ min) and volume assisted PCF (VPCF; 252 +/- 45 L/min) (F = 66.13, p < 0.001). MIP (34 +/- 13 cmH2O) correlated significantly with both UPCF and all three assisted PCFs as well as MEP (27 +/- 10 cmH2O) (p < 0.001). Both MEP and MIP, which are the markers of respiratory muscle weakness, should be taken into account in the study of cough effectiveness.

Effect of neuromuscular electrical stimulation on cough capacity and pulmonary function in patients with acute cervical cord injury

OBJECTIVE

To assess the effectiveness of neuromuscular electrical stimulation (NMES) on cough capacity and prevention of pulmonary complication in patients with acute cervical cord injury.

DESIGN

A randomized controlled trial.

SUBJECTS

Twenty-six tetraplegic patients with cervical spinal cord injury, 13 in the NMES therapy group and 13 in the control group.

METHODS

NMES was applied to the clavicular portion of the pectoralis major and abdominal muscle. Pulmonary function tests were performed before and after therapy, and at 3 months and 6 months follow-up. The pulmonary complications in this 6-month follow-up period were also recorded.

RESULTS

After the 4-week therapy, and at 3 months and 6 months follow-up testing, patients in the NMES therapy group displayed significant improvement in their peak expiratory flow, forced expiratory volume in 1 second, forced vital capacity, maximal expiratory pressure and maximal inspiratory pressure, compared with those in the control group (p<0.05). Patients in the NMES therapy group also had fewer pulmonary complications in the follow-up period.

CONCLUSION

NMES over the pectoralis and abdominal muscles might improve cough capacity and pulmonary function in cervical spinal cord injury with tetraplegia. This improvement might last for 6 months. With this improvement, pulmonary complications were reduced.

Spinal cord stimulation: a new method to produce an effective cough in patients with spinal cord injury

Patients with spinal cord injury have an increased risk of developing respiratory tract infections as the result of expiratory muscle paralysis and consequent inability to cough. We have developed a method by which the expiratory muscles can be activated via lower thoracic and upper lumbar spinal cord stimulation to produce an effective cough mechanism. In a tetraplegic patient who required frequent (8.57+/-2.3 times per week [mean+/-SEM]) caregiver assistance to facilitate airway clearance and expectoration of secretions, three epidural electrodes were applied in the T9, T11, and L1 spinal cord regions. During stimulation at the T9 and L1 levels, airway pressures were 90 and 82 cm H2O, respectively. Peak expiratory flow rates were 6.4 L/s and 5.0 L/s; respectively. During combined (T9+L1) stimulation, airway pressure and expiratory flow rate increased to 132 cm H2O and 7.4 L/s, respectively. Addition of the third lead did not result in further increases in pressure generation. These values are characteristic of those observed with a normal subject. Because the patient is able to trigger the device independently, he no longer requires caregiver support for airway management. If confirmed in additional patients, spinal cord stimulation may be a useful method to restore an effective cough mechanism in patients with spinal cord injury.

Nonpharmacologic airway clearance therapies: ACCP evidence-based clinical practice guidelines

BACKGROUND

Airway clearance may be impaired in disorders associated with abnormal cough mechanics, altered mucus rheology, altered mucociliary clearance, or structural airway defects. A variety of interventions are used to enhance airway clearance with the goal of improving lung mechanics and gas exchange, and preventing atelectasis and infection.

METHOD

A formal systematic review of nonpharmacologic protussive therapies was performed and constitutes the basis for this section of the guideline. In addition, the articles reviewed were found using the same methodology but were not limited to those that focused only on cough as a symptom. The MEDLINE database was searched for this review and consisted of studies published in the English language between 1960 and April 2004. The search terms used were "chest physiotherapy," "forced expiratory technique," "positive expiratory pressure," "high frequency chest compression," "insufflation," and "exsufflation."

RESULTS

In general, studies of nonpharmacologic methods of improving cough clearance are limited by methodological constraints, and most were conducted only in patients with cystic fibrosis. Chest physiotherapy, including postural drainage, chest wall percussion and vibration, and a forced expiration technique (called huffing), increase airway clearance as assessed by sputum characteristics (ie, volume, weight, and viscosity) and clearance of the radioaerosol from the lung, but the long-term efficacy of these techniques compared with unassisted cough alone is unknown. Other devices that allow patients to achieve the same benefits derived from chest physiotherapy without the assistance of a caregiver appear to be as effective as chest physiotherapy in increasing sputum production.

CONCLUSIONS

Some nonpharmacologic therapies are effective in increasing sputum production, but their long-term efficacy in improving outcomes compared with unassisted cough alone is unknown.

Relationship between inspiratory muscle strength and cough capacity in cervical spinal cord injured patients

STUDY DESIGN

Prospective single centre study.

OBJECTIVES

Pulmonary rehabilitation focuses on improving the expiratory muscle function in order to increase the reduced cough capacity in patients with cervical spinal cord injuries (SCI). However, an improvement in the inspiratory function is also important for coughing effectively. Therefore, this study was to examine the significance of the inspiratory muscle strength on the cough capacity in the patients with a cervical SCI.

SETTING

SCI unit, Yonsei Rehabilitation Hospital, Seoul, Korea.

METHODS

The vital capacity (VC), maximum inspiratory pressure (MIP), and maximum expiratory pressure (MEP) were measured. Moreover, the unassisted peak cough flow (PCF) and assisted PCF under three conditions were evaluated.

RESULTS

All three assisted cough methods showed a significantly higher value than the unassisted method (P < 0.001). The VC correlated with the voluntary cough capacity and the MIP (R = 0.749) correlated more significantly with the VC than the MEP (R = 0.438) (P < 0.01). The MIP showed a higher correlation with both the unassisted PCF and all three assisted PCFs than the MEP (P < 0.001).

CONCLUSIONS

The management of the inspiratory muscle strength should be considered in the pulmonary rehabilitation at cervical SCI patients.

Restoration of respiratory muscle function following spinal cord injury

Respiratory complications are a leading cause of morbidity and mortality in patients with spinal cord injury. Several techniques, currently available or in development, have the capacity to restore respiratory muscle function allowing these patients to live more normal lives and hopefully reduce the incidence of respiratory complications. Bilateral phrenic nerve pacing, a clinically accepted technique to restore inspiratory muscle function, allows patients with ventilator dependent tetraplegia complete freedom from mechanical ventilation. Compared to mechanical ventilation, phrenic nerve pacing provides patients with increased mobility, improved speech, improved comfort level and reduction in health care costs. The results of clinical trials of laparoscopically placed intramuscular diaphragm electrodes suggest that diaphragm pacing can also be achieved without the need for a thoracotomy and associated long hospital stay, and without manipulation of the phrenic nerve which carries a risk of phrenic nerve injury. Other clinical trials are being performed to restore inspiratory intercostal function. In patients with only unilateral phrenic nerve function who are not candidates for phrenic nerve pacing, combined intercostal and unilateral diaphragm pacing appears to provide benefits similar to that of bilateral diaphragm pacing. Clinical trials are also underway to restore expiratory muscle function. Magnetic stimulation, surface stimulation and spinal cord stimulation of the expiratory muscles are promising techniques to restore an effective cough mechanism in this patient population. These techniques hold promise to reduce the incidence of respiratory tract infections, atelectasis and respiratory failure in patients with spinal cord injury and reduce the morbidity and mortality associated with these complications.

Assisted cough and pulmonary compliance in patients with Duchenne muscular dystrophy

The aim of this study was to investigate the factors affecting cough ability, and to compare the assisted cough methods in patients with Duchenne muscular dystrophy (DMD). A total seventy-one male patients with DMD were included in the study. The vital capacity (VC) and maximum insufflation capacity (MIC) were measured. The unassisted peak cough flow (UPCF) and three different techniques of assisted peak cough flow were evaluated. UPCF measurements were possible for all 71 subjects. But when performing the three different assisted cough techniques, peak cough flows (PCFs) could be obtained from only 51 subjects. The mean value of MICs (1801 +/- 780 cc) was higher than that of VCs (1502 +/- 765 cc) (p< 0.01). All three assisted cough methods showed a significantly higher value than the unassisted method (F=80.92, p< 0.01). The manual assisted PCF under MIC (MPCFmic) significantly exceeded those produced by manual assisted PCF (MPCF) or PCF under MIC (PCFmic). The positive correlation between the MIC, VC difference (MIC-VC), and the difference between PCFmic and UPCF (PCFmic-UPCF) was seen (r=0.572, p< 0.01). The preservation of pulmonary compliance is important for the development of an effective cough as well as assisting the compression and expulsive phases. Thus, the clinical importance of the inspiratory phase and pulmonary compliance in assisting a cough should be emphasized.

Baclofen pump intervention for spasticity affecting pulmonary function

INTRODUCTION

Muscle spasticity may adversely affect pulmonary function after spinal cord injury (SCI). However, there is limited information regarding the treatment of spasticity as a determinant of pulmonary function. This study presents the case of a man with C4 tetraplegia who had severe spasticity and difficulty weaning from ventilatory support.

METHODS

Case presentation.

RESULTS

Severe spasticity likely contributed to respiratory compromise in this patient. Successful and rapid weaning from the ventilator occurred within 3 weeks of baclofen pump placement.

CONCLUSIONS

Randomized clinical trials among SCI patients with significant spasticity are needed to determine whether intervention with a baclofen pump facilitates earlier ventilatory weaning.