Validation of a Simplified MATRx Plus

Sleep apnea (OSA) is a condition in which the air passage in the throat closes or partly closes during sleep and repeatedly interrupts breathing. The standard treatment for sleep apnea is continuous positive airway pressure (CPAP), but it is not suitable for all patients. Another treatment is to use an oral appliance in your mouth when you sleep. The appliance covers the upper and lower teeth and acts to pull the lower jaw forward, opening the throat passage and allowing normal breathing.

Oral appliance therapy does not treat sleep apnea effectively in everyone. In order to identify the people in whom oral appliance therapy will work, Zephyr Sleep Technologies has invented a feedback-controlled device that tests various positions of the lower jaw. This commercially available device, known as MATRx plus, is a Health Canada approved and FDA cleared motorized dental positioner that can be used in an overnight sleep study performed in the home. Temporary dental impression trays cover your upper and lower teeth. These are attached to a small motor that slowly and gently pulls your lower jaw forward under the control of a computer in response to real-time breathing events. The commercial MATRx plus device uses measures of airflow from a nasal cannula and blood oxygen saturation from a pulse oximeter to guide the movement of the lower jaw during the test. Though the test is accurate, the equipment can be somewhat cumbersome to apply. The purpose of the study is to validate a simplified version of the test that requires fewer sensors and sleep time.

We have previously carried out three research studies leading to the development of the feedback-controlled mandibular positioner. These studies, two of which used early prototypes of the device and one that used the commercial MATRx plus device, showed that the feedback-control software used was very accurate and was able to identify successful candidates in a home setting.

No serious or permanent problems or risks were identified in any of the previous research studies. Participants reported minor tooth and gum discomfort on the morning following the test and other minor issues including dry mouth, excessive saliva, and being unable to sleep. The previous studies have established the safety and efficacy of the device using a device prototype. The purpose of the present study is to determine if the efficacy of the device is maintained when fewer sensors are used and the requirement for sleep time is reduced.

The study will collect data over one night in a sleep laboratory and a series of nights in the home. Following the study, you will be told if you are a suitable candidate for oral appliance therapy. If you do not already have a custom oral appliance, one will be provided to you. During the study, the Principal Investigator and study dentist will be blinded to the results of your tests. In the event of an emergency, the Principal Investigator can be unblinded to your test results.

Up to 46 individuals will be recruited for this study. Study participants will need to attend visits at multiple centres located in Calgary, Alberta.

Inclusion criteria

• Aged between 21 and 80 years
• Obstructive sleep apnea (ODI > 10 h-1)
• Body mass index < 45 kg/m2
• Neck circumference < 50 cm
• Absence of severe oxyhemoglobin desaturation during sleep, indicated by a mean value of oxyhemoglobin saturation (SaO2) > 87%
• Mandibular range of motion > 5 mm
• Adequate dentition (10 upper and 10 lower teeth)
• Ability to understand and provide informed consent
• Ability and willingness to meet the required schedule

Exclusion criteria

• Inability to breathe comfortably through the nose
• Central Sleep Apnea (> 50% of apneas are central)
• Anticipated change in medical therapy that could alter the severity of OSA during the protocol
• Anticipated change in body weight (5% or more) during the protocol
• Symptomatic, non-respiratory sleep disorder, e.g., restless leg syndrome or chronic insomnia
• Severe respiratory disorder(s) other than sleep disordered breathing
• Loose teeth, faulty restorations, or advanced periodontal disease
• Participation in other studies that could interfere with study protocol
• Pregnant or nursing
• Heart failure
• Cerebral vascular incident within the last 12 months
• Use of pacemaker or other life supporting device
• Regular use of CPAP or oral appliance therapy within 5 days of the PSG or HSAT (individuals on therapy wishing to participate may opt to cease therapy for the 5 nights prior to each test)