Research Fellow, NeuRA
Senior Staff Specialist, Spinal Unit, POWH
Conjoint Senior Lecturer, Faculty of Public Health, UNSW
Visiting Fellow, Centre for Clinical Governance Research in Health, UNSW
Dr Bon San Bonne Lee is a spinal cord injuries (SCI) specialist physician and researcher who has developed a broad, collaborative research perspective in the area of SCI and is a leader in the area of SCI urinary tract infection (UTI) prevention. His training is uniquely multidisciplinary, having postgraduate Masters degrees in clinical epidemiology (USYD), management (health administration UNSW) and a graduate certificate in information technology (UTS) as well as his specialist AFRM/RACP qualifications including the rehabilitation college medal for his fellowship exams and the Adrian Paul prize for research for new fellows.
Spinal cord injury (SCI) results in the loss of function to not only voluntary motor control, but also to the regulatory systems that control bodily processes. Orthostatic (postural) hypotension (OH) is a common clinical feature in SCI patients, affecting up to 73% of patients with cervical spine and upper thoracic spine injuries during mobilisation and postural changes. This often results in symptoms of dizziness, light-headedness, fatigue and confusion, in turn limiting individual participation in physical rehabilitation and restricting progress towards regaining function and independence.
Therapeutic interventions are centred around ameliorating symptoms of OH; however, options for patients remain limited. Non-pharmacological treatments have had little success at treating hypotension in the long-term, while pharmacological interventions are used only when necessary as they may contribute to hypertension and even worsen episodes of autonomic dysreflexia, a life-threatening condition.
Functional Electrical Stimulation (FES) is one of the only interventions that has been shown to display some benefit in improving OH. Recently, stimulation of the lower limbs has been shown to acutely increase blood pressure in patients with SCI. Our recent projects have involved the use of FES applied over the abdominal muscles, termed abdominal FES, for SCI patients at risk of respiratory complications with promising results. As this same population is at risk of orthostatic hypotension, this study aims to determine whether abdominal stimulation can also be used to help this condition.
Based on our previous research, we believe that abdominal FES will increase blood pressure acutely during an orthostatic challenge in individuals with acute spinal cord injury, allowing for a longer time spent in a standing position. This will facilitate more effective rehabilitation, therefore improving quality of life and decreasing associated medical complications.
While tetraplegia is commonly associated with paralysis of all four limbs, paralysis also affects the major respiratory muscles, namely the diaphragm, abdominal and intercostal muscles. The reduction in respiratory function results in approximately 40% of tetraplegic patients requiring mechanical ventilation in the acute stage (first six weeks) of injury to support respiration. The use of mechanical ventilation increases lifelong morbidity and mortality, delays rehabilitation, results in longer hospital stays and costs the health care provider an additional $2,000 per patient per day.
Surface electrical stimulation of the abdominal muscles, termed Abdominal Functional Electrical Stimulation (FES), can contract the abdominal muscles, even when paralysed. We have shown that surface FES of the abdominal muscles, termed Abdominal FES, improves respiratory function in tetraplegia, and respiratory function is a known predictor of mechanical ventilation time. Dr McCaughey’s pilot work also shows that eight weeks of abdominal FES is a feasible method to reduce mechanical ventilation time in acute tetraplegia.
Despite these positive results, a lack of data from randomised control trials, and lack of a standard Abdominal FES protocol, has prevented this technology from being adopted as a standard clinical treatment.
This project will provide the first information on the effectiveness and cost-effectiveness of Abdominal FES to reduce mechanical ventilation duration in tetraplegia. In addition, it will provide detailed information about respiratory function and its impact on quality of life in tetraplegia.
This is an international collaboration brings together leading research and medical teams from: Neuroscience Research Australia, the Prince of Wales Hospital, Royal North Shore Hospital, Austin Health and Fiona Stanley Hospital in Australia; The Indian Spinal Cord Injury Centre and the Christian Medical College, Vellore, in India; The Queen Elizabeth National Spinal Injuries Unit and the University of Glasgow in Scotland; Middlemore Hospital in Auckland, New Zealand, and the University of Alberta and McMaster University in Canada.
While tetraplegia is often characterized by paralysis of all four limbs, paralysis also affects the major respiratory muscles, namely the diaphragm and abdominal and intercostal muscles. This reduces respiratory function, with associated respiratory complications, such as pneumonia and atelectasis. Such complications are a leading cause of illness and death for the tetraplegic population. Up to 68% of patients with tetraplegia have a respiratory complication in the first 6 weeks (i.e. the acute stage) of injury. A reduction in respiratory complications in acute tetraplegia would decrease illness and death, reduce rehabilitation time, improve quality of life, and result in a large cost saving for global health systems.
Surface electrical stimulation of the abdominal muscles, termed Abdominal Functional Electrical Stimulation (FES), can contract the abdominal muscles, even when paralysed. We have shown that the repeated application of Abdominal FES improves the respiratory function of people with tetraplegia. However, while respiratory function is a predictor of respiratory complications in tetraplegia, evidence that Abdominal FES reduces respiratory complications is only anecdotal. We will undertake the first prospective, multi-centre, randomised placebo controlled trial, to determine whether Abdominal FES reduces respiratory complications in acute tetraplegia.
Definitive evidence of the effectiveness of Abdominal FES to reduce respiratory complications in tetraplegia will drive the rapid worldwide translation of this low cost and easily applied technology for this vulnerable patient group. This will decrease illness and death, reduce rehabilitation time, improve quality of life, and result in a large cost saving for global health systems.
This international collaboration brings together leading research and medical teams from: Neuroscience Research Australia, the Prince of Wales Hospital, and the Royal North Shore Hospital in Australia; The Indian Spinal Cord Injury Centre; Chang Mai University Hospital in Thailand and The Queen Elizabeth National Spinal Injuries Unit and the University of Glasgow in Scotland.
Respiratory complications are the major cause of death for people with spinal cord injuries. People with a high level spinal cord injury are 150 times more likely to die from pneumonia than the general population. This is because after high level spinal cord injury, people have a reduced ability to cough and to clear secretions from the lungs. The major group of muscles that produce a cough are the abdominal muscles. If the abdominal muscles are paralysed after spinal cord injury then the strength of the cough will be severely reduced. In our lab, we are looking at ways to improve cough in people with spinal cord injury by using surface functional electrical stimulation of the abdominal muscles. We have shown that this type of stimulation can improve cough significantly. We are now looking for ways to further improve cough through muscle training as well as ways to develop a portable stimulator that would allow independent activation of a cough.
After cervical spinal cord injury (SCI), the respiratory muscles are partly or completely paralysed. This has two major clinical consequences: a decreased ability to get air into the lungs and a decreased ability to cough and remove secretions. This results in a lifetime of recurrent respiratory tract infections (2/year/person) that often progress to pneumonia with frequent and extended hospital admissions. People with cervical SCI are 150 times more likely to die from respiratory complications than the general population, as many as 28% die within the first year after injury. For those that survive the first year, a cervical SCI has a lifetime cost of $9.5million, a large proportion of which is attributed to respiratory-related complications. A recent longitudinal study of people with cervical SCI showed that respiratory muscle weakness is associated with incidental pneumonia. Respiratory muscle weakness also causes dyspnoea (breathlessness) and sleep-disordered breathing, which is 4-10 times more prevalent in people with SCI than the able-bodied population. Therefore, there is an urgent need to identify a simple and cost-effective treatment for respiratory muscles weakness to prevent respiratory complications after SCI, improve quality of life and reduce the burden on the healthcare system.
Our primary aim is to determine definitively the effectiveness of training on respiratory muscle strength, respiratory physiology and health outcomes. To do this we will conduct a randomised controlled trial 2 times bigger than the largest previous study, of respiratory muscle resistive load training in individuals with acute and chronic cervical SCI. The project will provide critical new knowledge about the efficacy of a simple and inexpensive respiratory muscle training regime, which can be applied immediately in the hospital and community, to minimise respiratory morbidity in people with SCI. This project also provides a unique opportunity to investigate other consequential effects of long-term respiratory muscle training that have never been studied in people with SCI. These include effects on cough efficacy, sleep-disordered breathing, breathlessness, respiratory morbidity, respiratory health and neural drive to the diaphragm, as well as quality of life.