Introduction/Background
Snoring and obstructive sleep apnea (OSA) are common among the adult population; a mean of 22% and 17% of the women are affected. Obstructive sleep apnea is related to several negative health effects, such as sleepiness, hypertension, cardiovascular disease, and cognitive impairment. Continuous positive airway pressure (CPAP), oral appliances (OA), as well as oropharyngeal surgery in selected cases are available as a treatment for OSA. The same methods can be used for reducing snoring, but the cost for the devices is high, and the compliance tends to be low, although snoring affects the individual as well as the bed partner. Snoring produces vibrations in the upper airway, and over time, it can affect both the motor and sensory function of the tissue in the upper airway. The deterioration process is unknown, but previously published data shows a correlation between the level of snoring/OSA and altered sensory and motor function. This is probably due to the adverse effects of the vibrations and stretching of the nerves and muscles in the airway during snoring and apneas. Our and other research groups have presented similar results and hypothesize that the deterioration may explain why the airway slowly tends to collapse more frequently. This may also explain why more than half of the habitual snorers show deviant swallowing function and thereby have a higher risk of aspiration. It is unknown if this degenerative process of the upper airway is possible to slow down, stop or perhaps even be reversed and thereby improve the sensory and motor function by treatment that decrease or determine snoring and OSA. However, recent data give promising indications that myofunctional training of the upper airway can decrease levels and intensity of snoring and reduce the apnea-hypopnea index (AHI).
Oral screen training can affect brain plasticity and have a strengthening effect on oral and pharyngeal muscles. Oral screen training is used to improve oral and pharyngeal muscle function and has been reported to improve swallowing function in patients suffering from dysphagia including aspiration after stroke. Further, it has been reported to be efficient for the treatment of dysphagia caused by other conditions.
Daily neuromuscular electrical training (NMES) by an oral device eXciteosa® has shown promising results in patients with primary snoring and mild sleep apnea, reducing objective and subjective snoring. Orofacial training guided by an occupational therapist (group training) has also shown positive results in adhering to the training program and affecting the AHI, reducing it in persons aged 60 and younger.
The aim of the present study is, therefore, to assess 1) the impact of three different training methods to reduce AHI among adults with mild to moderate sleep apnea and 2) if the oral screen training can lower the level and intensity of snoring, change levels of sleepiness, quality of life and strength of the tongue muscle.
Material and methods
Subjects and procedure In total 141 consecutive adult subjects, 71 men and 70 women, referred to Umeå University Hospital and Köge University Hospital, due to symptoms of snoring and/or mild to moderate sleep apnea, will be included. The subjects included in Umea will get three months of intervention with oral screen training or serve as controls. The subjects included in Köge will get either a three-month intervention with orofacial group training led by an occupational therapist, three months intervention with a daytime mouth device for muscular training, eXciteosa® or serve as controls. At baseline, all subjects will undergo two overnight ambulatory sleep apnea recordings and answer questionnaires regarding snoring, daytime sleepiness, and quality of life. The demography, including sex, age, and BMI, will be recorded. Tounge strength will be measured.
In Umeå, the participants will be randomly assigned to either an initial three-month intervention with oral screen training or a three-month intervention delay, serving as controls. In Köge, the participants will be randomly assigned to either a three-month intervention with eXciteosa®, group training with an occupational therapist, or serve as controls. After three months, all the above questions and parameters will be registered again.
Inclusion criteria are men and women with AHI 10 - 29 seeking for problems with snoring and obstructive sleep apnea, age 18 to 75.
Exclusion criteria are subjects with previous soft palate surgery, 9 \< AHI \> 29, smokers, New York Heart Association Functional Classification, NYHA ≥ 3. BMI \>34,9.
Main outcome measurements The primary outcome is the change in the apnea-hypopnea index (AHI) before and after three months of training with one of the modalities.
Secondary outcome measurements The secondary outcomes are a change in snoring frequency and sound level dB (A) and a a questionnaire concerning snoring, the Basic Nordic Sleep Questionnaire (BNSQ).
Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS) change in quality of life using the short form -36 (SF-36) and change in muscle strength before and after treatment.
Oral screen (Only in Sweden) Strength training of the oral and pharyngeal muscles is performed with an oral screen (OS)(IQoro®). The OS is a device that has an effect both on the brain plasticity and a strengthening effect of oral and pharyngeal muscles. The OS is placed pre-dentally behind closed lips. The participant pulls the OS forward in a horizontal direction with strong pressure for 5 to 10 seconds while firmly resisting the pressure with tightened lips. The exercise is repeated three times, with 3 seconds of rest between repetitions, and is performed 3 times per day.
Neuromuscular electrical training (NMES) (Only in Denmark) Strength training of the oral and pharyngeal muscles is performed by an oral device used for twenty minutes every day (eXciteosa®). The device gives electrical pulses to the surrounding tissue, mainly the tongue.
Group training with an occupational therapist (Only in Denmark) Strength training of the oral and pharyngeal muscles is performed in a group led by an occupational therapist.
Sleep apnea recordings The investigators will use two types of recording devices, Nox-T3® (Nox-T3®, Nox Medical Inc.
Reykjavik, Iceland) and SleepImage® System (MyCardio LLC, Denver, CO, USA) In the overnight home sleep studies, recordings will be scored manually (Nox-T3®), and the scorer is blinded to the treatment (blinded endpoint). All recordings will be done over two nights, at baseline and follow-up to minimize the effect of night-to-night variability.
The duration of sleep will be estimated from the recordings. An apnea is defined as a drop in the peak thermal sensor excursion of \> 90 of the baseline lasting at least 10 seconds, while a hypopnea is defined as a 50% reduction in airflow compared with baseline, combined with an oxygen desaturation of \> 3%.
Obstructive sleep apnea is defined as a mean of five or more obstructive apneas and hypopneas per hour of sleep. Mild sleep apnea is considered when the apnea-hypopnea index is 5 to \< 15, moderate sleep apnea when the apnea-hypopnea index is 15 to \< 30, and severe sleep apnea when the apnea-hypopnea index is \> 30.
The snoring frequency and sound level dB (A) will be measured with a microphone within the recording device (Nox-T3®) and a questionnaire regarding the level and frequencies of the snoring (BNSQ).
Additionally, the investigators will also use a new device called Sleepimage®. The device measures plethysmography trace, heart (pulse) rate, heart (pulse) rate variability, respiration, blood oxygenation (SpO2), and actigraphy. The device is a ring worn on any finger on the left hand and collects sleep data during the night. The result is then translated into a report giving data about sleep quality, any sleep pathology, and sleep duration. The device has FDA approval At present, there is no "golden standard" for measuring snoring. However, the methods and devices have improved, and a recent comparison of different tools for measuring snoring suggested the use of the T3 advice for the recordings.
Measuring strength:
Tounge strength is measured with the Iowa Oral Performance Instrument, IOPI®.
Questionnaires:
The Basic Nordic Sleep Questionnaire (BNSQ) BNSQ was developed in Nordic countries to develop a standardized questionnaire. The task force developing it was set up in 1988 by the Scandinavian Sleep Research Society. It consists of 21 questions on sleep, evaluating the past three months. The questions can be answered on a five-point scale, 1 to 5. It has been translated into Swedish and Danish.
Epworth Sleepiness Scale (ESS) ESS is a validated questionnaire assessing the probability of falling asleep in eight different situations in daily life with four alternative answers ranging from 0-3. The score ranges from 0-24, and the higher the score, the higher the level of daytime sleepiness. The ESS has been proven to correlate to the AHI in the Sleep Heart Health Study, showing higher levels of the ESS when the AHI was higher. There is also a correlation between the incidences of road traffic accidents and the ESS, as well as health-related questions relating to quality of life and the ESS. Daytime sleepiness is considered at a summary score of above 10. It has been translated into Swedish and Danish.
Short form 36 (SF-36) The SF-36 is a validated questionnaire that evaluates the quality of life in eight different health-related domains. It has been translated into Swedish and Danish.
Statistics A power calculation was performed based on Guimaraes et al.2009 results. The AHI was used in the calculation. Independent samples t-test, two-sided, anticipated effect size (Cohen's d) 0.8 (high), power ≥80%, probability level 5%. This gives a minimal sample size of 26 per group. The expected dropout of patients during the trial is 25% corresponding to a total of 9 patients in each group. To accommodate for this potential, the sample size was increased to 105 (35 in each group).
The study will use a prospective randomized open-blinded endpoint (PROBE) design with baseline measurements, intervention phase and follow-up measurements, and controls without intervention. Primary and secondary outcomes are values of AHI, snoring, BNSQ, ESS, and SF-36. These measures will be compared for baseline data and follow-up data by applying an independent-samples t-test, chi2 for proportion. ANCOVA will be used to estimate adjusted differences between the groups, adjusting for baseline values. Statistical analyses will be conducted using SPSS® version 28. A statistically significant level is defined as P\<0,05.
Ethics The study has Ethical approval in Sweden and Denmark. The participants, men, and women, included in the study will be informed both orally and in written information before leaving informed consent. The participants can, without explanation, end the study without any negative impact on future care.
