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Background
Most people with motor neurone disease (MND)/amyotrophic lateral sclerosis (ALS) survive 2 to 3 years from diagnosis as progressive motor weakness leads to respiratory failure and death. It was estimated in Australia in 2015 that MND was associated with economic and burden of disease costs of $1.13 million per person diagnosed, with a total annual cost of $2.37 billion [1]. These costs are primarily driven by the loss of life due to premature mortality and the immense financial and disability burden to the individual and their families coping with rapid decline and death.
The benefits of non-invasive ventilation (NIV) to treat chronic respiratory failure and reduce the rate of respiratory function decline are well-established in people with MND. A 2006 single-site randomised controlled trial (RCT) of NIV versus no-NIV demonstrated a modest overall survival benefit. Five single-site cohorts have also associated NIV use with increased survival in MND, including a 20-year study conducted by members of the current research team [2, 3, 4, 5–6], which demonstrated that NIV slows respiratory decline and improves survival by a median of 13 months [4].
Despite these benefits [7], methods for commencing NIV are variable, and there is little consensus on how best to implement NIV. A number of clinical practice models using a variety of evaluation tools have been reported, ranging from inpatient hospital assessments to ambulatory or home-based models [4, 7, 8–9]. Some of the variation in practice is attributable to inequitable patient access and local, state and national differences in healthcare funding and models [10, 11].
Undertaking an overnight sleep study (polysomnography; PSG) to support the initiation of NIV uniquely provides direct observation of patient-ventilator interaction, respiratory control and an assessment of sleep quality. Patient-ventilator asynchrony is a mismatch between neural (user) and mechanical (ventilator) drive and timing [12] and has been described in the critical care [13] and NIV literature [14, 15]. Uncontrolled studies have demonstrated frequent patient-ventilator asynchrony in those using nocturnal NIV following daytime clinical titration [14, 15–16], which improved with setting adjustments [15, 16]. Associations have been found between increased levels of patient-ventilator asynchrony and more arousals from sleep [17], less rapid eye movement (REM) sleep, lower sleep efficiency [15], worse nocturnal gas exchange [15] and reduced NIV tolerance [18].
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