Combination therapy for obstructive sleep apnoea.

The Oventus O2Vent T is a custom-made oral appliance or Mandibular Advancement Device (MAD), similar in appearance to a mouth guard designed to treat snoring and sleep apnoea. It is made up of two parts. The main structure which forms the breathing port at the front leading to the airways on each side to the rear of the appliance, is made from polished medical grade titanium with a polymer insert. The lower portion is made from dual laminate and is positioned in an advanced position to bring the jaw forward and adjusted using a screw titration mechanism. The O2Vent T Mandibular Advancement Device (MAD) is delivered by a qualified dentist and worn every night during sleep and removed on waking. The acclimatization and treatment optimization period may vary from 1 week to several months. This involves getting used to wearing the device and establishing the optimum jaw position to balance comfort and resolution of symptoms as assessed by the Dentist fitting the device, Further advancement of the lower jaw is obtained using the screw titration mechanism in the O2Vent T. People fitted and acclimatised to this device for the treatment of OSA will be asked to participate in this study. There are no study related procedures prior to acclimatization and treatment optimization.. Part A The study will involve a Level 1 in laboratory sleep study consisting of half night with and half the night without MAD in place, in order to assess efficacy based on the Apnoea-Hypopnoea Index (AHI) and to determine if the inclusion criteria for Part B is met. In addition to the standard clinical sleep study, nasal resistance will be evaluated. When the MAD is being worn, the device airway will remain open (MADopen) in this part of the study. Part B Participants who are deemed as non-responders to MAD based on a residual AHI > 10 events per hour sleep, will be asked to participate in Part B with a minimum of 1 week separating Part A and B. Part B study night will consist of another Level 1 in laboratory sleep study with additional measurements of pressures in the throat. CPAP will be applied during this single night study in a research laboratory setting by investigators experienced in complex sleep studies and the application of CPAP, via an interface or mask. .CPAP will be applied alone and in combination with MAD with the device airway open and closed i.e. CPAP-MADopen and CPAP-MADclosed and titrated based on flow limitation and/or epiglottic pressure. Closing and opening the device airway is established using a connector that either allows for or blocks flow through the device airway. There is no washout period in between the administration of the treatments during this overnight investigation as the immediate physiological responses to treatment are of interest. If time permits, a fourth condition will be examined. CPAP will be applied via the device airway (CPAPdevice-MAD) with the device airway being open for the application of CPAP. Part C Participants who take part in Part B and those with a residual AHI on MAD >5 events/h will be asked to return for a Level 1 in laboratory sleep study consisting of half night with MAD+ an expiratory valve over the oral airway on the device and half the night with MAD+ expiratory valve over the oral airway on the device + the nose in order to assess efficacy of combination therapy (MAD+ expiratory valves) on the Apnoea-Hypopnoea Index (AHI).