Study objectives: Oral appliance (OA) therapy is the leading alternative to continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA). It is well tolerated compared to CPAP. However, ≥50% of patients using OA therapy have incomplete resolution of their OSA. Combination therapy with CPAP and oral appliance (CPAP+OA) is a potential alternative for incomplete responders to OA therapy. This study aimed to determine the extent to which combination therapy reduces therapeutic CPAP requirements using gold standard physiological methodology in those who have an incomplete response to OA therapy alone. Methods: 16 incomplete responders (residual AHI> 10events/h) to a novel OA with a built-in oral airway were recruited (3F:13M, aged 31-65 years, BMI: 22-38kg/m2, residual AHI range 13-63events/h). Participants were fitted with a nasal mask, pneumotachograph, epiglottic pressure catheter and standard polysomnography equipment. CPAP titrations were performed during NREM supine sleep in each participant during 3 conditions (order randomized): 1) CPAP only, 2) CPAP+OA(oral airway open), and 3) CPAP+OA(oral airway closed). Results: OSA was resolved at pressures of 4±2 and 5±2cmH2O during CPAP+OA (oral airway open) and CPAP+OA (oral airway closed) conditions versus 8±2cmH2O during CPAP only (P<0.01). Negative epiglottic pressure swings in oral airway open and closed conditions were normalized to CPAP only levels (-2.5[-3.7,-2.6] vs. -2.3[-3.2,-2.4]vs. -2.1[-2.7,-2.3]cmH2O). Conclusions: Combined CPAP and OA therapy reduces therapeutic CPAP requirements by 35-45% and minimizes epiglottic pressure swings. This combination may be a therapeutic alternative for patients with incomplete responses to OA therapy alone and those who cannot tolerate high CPAP levels.

Study Objectives: High nasal resistance is associated with oral appliance treatment failure in obstructive sleep apnea (OSA). A novel oral appliance with a builtin oral airway has been shown to reduce pharyngeal pressure swings during sleep and may be efficacious in those with high nasal resistance. The role of posture and mandibular advancement on nasal resistance in OSA remains unclear. This study aimed to determine (1) the effects of posture and mandibular advancement on nasal resistance in OSA and (2) the efficacy of a new oral appliance device including in patients with high nasal resistance. Methods: A total of 39 people with OSA (7 females, apnea-hypopnea index (AHI) (mean ± standard deviation) = 29 ± 21 events/h) completed split-night polysomnography with and without oral appliance (order randomized). Prior to sleep, participants were instrumented with a nasal mask, pneumotachograph, and a choanal pressure catheter for gold standard nasal resistance quantification seated, supine and lateral (with and without oral appliance, order randomized). Results: Awake nasal resistance increased from seated, to supine, to lateral posture (median [interquartile range] = 1.

Study Objectives Mandibular advancement splint (MAS) therapy is a well-tolerated alternative to continuous positive airway pressure for obstructive sleep apnea (OSA). Other therapies, including nasal expiratory positive airway pressure (EPAP) valves, can also reduce OSA severity. However, >50% of patients have an incomplete or no therapeutic response with either therapy alone and thus remain at risk of adverse health outcomes. Combining these therapies may yield greater efficacy to provide a therapeutic solution for many incomplete/nonresponders to MAS therapy. Thus, this study evaluated the efficacy of combination therapy with MAS plus EPAP in incomplete/nonresponders to MAS alone. Methods Twenty-two people with OSA (apnea–hypopnea index [AHI] = 22 [13, 42] events/hr), who were incomplete/nonresponders (residual AHI > 5 events/hr) on an initial split-night polysomnography with a novel MAS device containing an oral airway, completed an additional split-night polysomnography with MAS + oral EPAP valve and MAS + oral and nasal EPAP valves (order randomized). Results Compared with MAS alone, MAS + oral EPAP significantly reduced the median total AHI, with further reductions with the MAS + oral/nasal EPAP combination (15 [10, 34] vs. 10 [7, 21] vs. 7 [3, 13] events/hr, p < 0.01). Larger reductions occurred in supine nonrapid eye movement AHI with MAS + oral/nasal EPAP combination therapy (ΔAHI = 23 events/hr, p < 0.01). OSA resolved (AHI < 5 events/hr) with MAS + oral/nasal EPAP in nine individuals and 13 had ≥50% reduction in AHI from no MAS. However, sleep efficiency was lower with MAS + oral/nasal EPAP versus MAS alone or MAS + oral EPAP (78 ± 19 vs. 87 ± 10 and 88 ± 10% respectively, p < 0.05). Conclusions Combination therapy with a novel MAS device and simple oral or oro-nasal EPAP valves reduces OSA severity to therapeutic levels for a substantial proportion of incomplete/nonresponders to MAS therapy alone. Clinical Trials Name: Targeted combination therapy: Physiological mechanistic studies to inform treatment for obstructive sleep apnea (OSA) URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=372279 Registration: ACTRN12617000492358 (Part C)

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