The efficacy of currently recommended treatments is uncertain in patients with mild to moderate obstructive sleep apnea (apnea-hypopnea index [AHI], 5-30). A group of 114 sleep clinic patients with an AHI of 5-30 have participated in a randomized controlled crossover trial of 3 months of treatment with each of nasal continuous positive airway pressure (CPAP), a mandibular advancement splint, and a placebo tablet. Outcomes were sleep fragmentation and hypoxemia, daytime sleepiness, quality of life, neurobehavioral function, and blood pressure. Both active treatments improved sleep outcomes, but positive airway pressure had a greater effect. The quality of life, symptoms, and subjective but not objective sleepiness improved to a similar degree with both treatments; however, many of the improvements seen in neuropsychologic function and mood were not better than the placebo effect. Some aspects of nocturnal blood pressure were improved with the splint but not with CPAP. This study has shown that although both CPAP and mandibular advancement splint effectively treated sleep-disordered breathing and sleepiness, the expected response in neurobehavioral function was incomplete. This may be due to the splint having a lesser therapeutic effect and CPAP being poorly tolerated and therefore used less in this patient group.

Background: Sleep hypoventilation has been proposed as a cause of progressive hypercapnic respiratory failure and death in patients with severe chronic obstructive pulmonary disease (COPD). A study was undertaken to determine the effects of nocturnal non-invasive bi-level pressure support ventilation (NIV) on survival, lung function and quality of life in patients with severe hypercapnic COPD. Method: A multicentre, open-label, randomised controlled trial of NIV plus long-term oxygen therapy (LTOT) versus LTOT alone was performed in four Australian University Hospital sleep/respiratory medicine departments in patients with severe stable smoking-related COPD (forced expiratory volume in 1 s (FEV 1.0 ) ,1.5 litres or ,50% predicted and ratio of FEV 1.0 to forced vital capacity (FVC) ,60% with awake arterial carbon dioxide tension (PaCO 2 ) .46 mm Hg and on LTOT for at least 3 months) and age ,80 years. Patients with sleep apnoea (apnoea-hypopnoea index .20/h) or morbid obesity (body mass index .40) were excluded. Outcome measures were survival, spirometry, arterial blood gases, polysomnography, general and disease-specific quality of life and mood. Results: 144 patients were randomised (72 to NIV + LTOT and 72 to LTOT alone). NIV improved sleep quality and sleep-related hypercapnia acutely, and patients complied well with therapy (mean (SD) nightly use 4.5 (3.2) h). Compared with LTOT alone, NIV (mean follow-up 2.21 years, range 0.01-5.59) showed an improvement in survival with the adjusted but not the unadjusted Cox model (adjusted hazard ratio (HR) 0.63, 95% CI 0.40 to 0.99, p = 0.045; unadjusted HR 0.82, 95% CI 0.53 to 1.25, p = NS). FEV

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