Positional Therapy to Treat Obstructive Sleep Apnea in Stroke Patients

1. BACKGROUND Obstructive sleep apnea is very common in stroke patients, with reported prevalence rates between 30% and 70%. Recent studies suggest that it represents both a risk factor and a consequence of stroke and affects stroke recovery, outcome, and recurrence. A case-control study found that stroke patients with OSA had worse neurological status, lower functional independence scores, and a longer period of hospitalization than stroke patients without OSA. Furthermore, leaving OSA untreated after stroke affects rehabilitation efforts and short- and long-term stroke recovery and outcomes. Current literature supports the implementation of treatment protocols for OSA post-stroke in stroke units. This warrants the need to improve treatment of OSA in stroke patients as a means of secondary prevention and improvement of stroke outcomes. 1.1 Treating OSA in stroke patients Continuous positive airway pressure (CPAP) is the current gold standard therapy for OSA in the general population. Early CPAP therapy was found to have a positive effect on long-term survival in ischaemic stroke patients with moderate-severe OSA. However, CPAP is generally poorly tolerated by stroke patients and has a low compliance. Another alternative therapy, nasal expiratory positive airway pressure (EPAP), was also found to be an ineffective alternative to CPAP in acute stroke patients with OSA. Since sleeping in the supine position increases the chance of sleep apnea due to the tendency of the tongue to fall back and block the pharyngeal airway, having stroke patients sleep in a lateral position may improve OSA severity. As sleeping in the supine position is very common in acute stroke patients, positional therapy that reduces supine sleep may be beneficial in treating OSA in stroke patients. Positional therapy was found to be as effective as CPAP therapy in patients of the general population with positional OSA and in those patients who are intolerant to CPAP therapy. A pilot RCT found that positional therapy reduced the amount of supine positioning by 36% and AHI was reduced by 19.5% in stroke patients. Despite the modest improvements observed from position therapy in stroke patients, there is still a need for a vigorous randomized controlled trial to study the effectiveness of positional therapy to reduce the severity of OSA in stroke patients.
2. RATIONALE It is of great importance to routinely diagnose and treat OSA after stroke because OSA is highly prevalent and influences rehabilitation and recovery efforts after stroke. Since CPAP, the current gold standard therapy for OSA, is poorly tolerated by stroke patients and is not conveniently accessible in the hospital, positional therapy for OSA may be a feasible alternative. Positional therapy belts have the advantages of being convenient for patients and may also be economically attractive, however they are not routinely used in Ontario hospital or clinics. Therefore, this warrants the investigation of the effectiveness and feasibility of positional therapy in stroke patients.
3. SIGNIFICANCE Our project could substantially change the way healthcare is delivered for stroke patients if it finds that treating OSA with positional therapy improves clinical outcomes after stroke. Since CPAP, the current gold-standard for treating OSA, is poorly tolerated in stroke patients, positional therapy has the potential to provide therapy that is convenient and easy to use for stroke patients. Positional therapy devices can also be easily used in patient hospital beds or homes to treat their OSA. This novel approach would have the potential to improve patient outcomes while reducing healthcare spending and could be easily applied to settings outside of Sunnybrook HSC. Although our study will only examine stroke patients, future work could examine the role of positional therapy in other patient populations. Overall, our study will have an important impact on healthcare delivery and optimizing patient outcomes.
4. RESEARCH OBJECTIVES

The primary objective of our randomized controlled trial is to determine whether positional therapy can effectively treat OSA in patients who have sustained a stroke. This will be evaluated by measuring OSA severity, as assessed by the apnea-hypopnea index (AHI) and oxygen desaturation. AHI and oxygen saturation are both measured using the Resmed ApneaLink device.

The secondary objectives include determining the effectiveness of positional therapy in reducing the time spent in the supine position during sleep. This will be measured using a portable body position sensor, available on the Resmed ApneaLink device. We will also assess if positional therapy improves actigraphy-derived measures (e.g. sleep efficiency and wake after sleep onset) by using Phillips Respironics actigraphy. Furthermore, we seek to explore whether positional therapy improves neurological outcomes (National Institutes of Health Stroke Scale, Montreal Cognitive Assessment, Modified Rankin), psychomotor outcomes (psychomotor vigilance test), psychosocial outcomes (depression, quality of life), performance of daily activities, daytime sleepiness, and length of stay in hospital.