Swallowing in OSA & CPAP Intolerance

This study has two parts: an observational part and an interventional part.

The goal of the observational part of the study is to look for variations in swallowing in adults with obstructive sleep apnea (OSA) and in adults who don't snore. The main questions it aims to answer are:

* Are there differences in swallowing between people with OSA and people who don't snore?
* Are there differences in swallowing between people with OSA who do well with continuous positive airway pressure (CPAP) therapy and those who struggle with CPAP?

This may help us better understand what causes OSA, which may help us develop alternate ways to treat or even prevent OSA. It may also help us improve care for people with OSA who struggle with CPAP. Participants will be aged 40-60 years, except women up to the age of 70 will be included in the healthy control (non-snorer) group.

Participants will:

* Undergo a type of x-ray study called a modified barium swallow study (MBS)
* Come to MetroHealth Medical Center for a measurement visit to:

  * assess the strength of their tongue, lips, and cheeks
  * assess the strength of their breathing muscles
  * assess for restrictions in tongue mobility (tongue ties)
  * observe their resting breathing
  * take photos of their mouth and posture
  * take videos of them drinking and eating
* Complete some questionnaires
* For successful CPAP users: we will download data from the chip in their CPAP device
* Do a home sleep test (except for successful CPAP users who have had a recent in-lab sleep test)

The goal of the interventional part of the study is to test swallowing exercises in people ages 40-60 years with OSA who struggle with CPAP. The main question it aims to answer is:

• Can swallowing exercises help people who struggle with CPAP sleep better with CPAP?

Participants will:

* Try to use CPAP for 2 weeks with individualized support
* Do all the investigations listed in the observational part of the study
* Do one or two courses of swallowing exercises, each of which would last 7 weeks. Participants will be asked to do daily exercises; exercises will take 20-30 minutes to perform.
* Try to use CPAP for 2 weeks after the course of exercises
* Repeat the investigations listed in the observational part of the study to see if changes occurred with the swallowing exercise intervention.

Obstructive sleep apnea (OSA) is a common disorder in which the throat narrows abnormally or even collapses fully during sleep. The narrowing leads to sleep disruption and increases the risk of many chronic health conditions. We do not understand why the throat narrows in some people during sleep but not in others. While being overweight or obese increases a person's risk of OSA, it is only one part of the problem. Some thin adults and children have OSA, and many overweight or obese people do not have OSA. In addition, many people with OSA struggle to benefit from current OSA treatments like continuous positive airway pressure (CPAP), which uses air pressure to hold the airway open during sleep. We need improved understanding of OSA in order to improve treatment of it.

The throat is used for swallowing as well as for breathing. Hence it should not be surprising if a throat that has trouble staying open during sleep might also have some abnormalities during swallowing. Indeed, some research has shown subtle abnormalities in swallowing in people who have snoring or OSA compared to people who don't snore at all. We would like to further develop this line of research.

This study has two arms: an observational arm to look for differences in swallowing, and an interventional arm to see if swallowing exercises can improve people's ability to use CPAP.

The purpose of the observational arm is to look for differences in swallowing between healthy people and people who have obstructive sleep apnea (OSA) using a variety of measurement techniques, some of which have not been done in the past. Understanding the differences in swallowing may help us to develop new treatments for OSA. It may also help us to figure out how to prevent OSA from developing in the first place. We are also looking to see if there are swallowing differences between people with OSA who don't tolerate CPAP compared to people who do well with CPAP. If there are differences, these differences may help us better understand why some people do not tolerate CPAP, and may lead to the development of novel treatments such as exercise therapies to help them do better with CPAP.

The interventional arm will test exercise therapies to see if they will help people who struggle with CPAP. The goal is not to cure OSA, but to help people be able to use CPAP better so that they can sleep better. Participants who have abnormalities in their swallowing study will get exercises from speech language pathologists (SLP, also known as speech therapists) aimed at trying to correct those abnormalities. Participants will then try to use CPAP again. Participants who still can't sleep well with CPAP after those exercises, or who don't have abnormalities on the swallowing study, will get another type of exercise therapy based on an exercise technique called orofacial myofunctional therapy (OMT). This therapy aims to train exclusive nasal breathing and correct variations in the swallow. This sort of exercise technique has had some success in improving CPAP use as well as in reducing the severity of OSA. We have created a streamlined exercise protocol based on these techniques that we hope will provide better results in a shorter period of time. At the end of the exercise interventions, the participants will repeat the investigations that were done at the beginning of the study.

Investigations will include home sleep testing, CPAP trials (only for participants with OSA and CPAP intolerance), a modified barium swallow study (MBS), a measurement visit, and questionnaires. During the measurement visit, there will be assessments of the strength of the tongue, lips, and cheeks, assessment of nasal airflow, respiratory muscle strength, restrictions in tongue mobility (tongue tie), posture, dental and facial form, and eating and drinking. The modified barium swallow study uses x-rays; the amount of radiation from the procedure is about what a person would receive from about 4.5 months of background radiation. It is a little bit more radiation than what a person would receive from a mammogram, but much less than what a person would receive from a CT scan.

Eligibility Criteria:
Inclusion Criteria for healthy airways participants:

* Naturally ideal dental occlusion without orthodontic intervention, including successful eruption of wisdom teeth (without significant dental crowding, though minor rotation of less than 4 teeth will be acceptable)
* No sleep-related complaints
* No snoring.
* They should be missing no more than 4 of their natural teeth, and these should have been lost to decay or accident rather than due to crowding. A person whose wisdom teeth came in successfully but were extracted "preventatively" will be eligible for the study.
* Should be getting at least 6 hours of sleep nightly.
* BMI between 18.5 and 35

Inclusion Criteria for participants with OSA who are successful CPAP users:

* Participant will have experienced significant benefits from therapy and have had such benefit since the first night of use. Participant should have no significant sleep complaints when using CPAP.
* Uses CPAP \> 6 hours of nightly use on \> 90% of nights using a nasal mask.
* Residual device AHI \< 5 events/hour.
* Has used CPAP for at least 12 months.
* Symptomatic at diagnosis, with polysomnography (PSG) showing AASM AHI 5-60 and symptoms attributable to OSA, with greater than 75% of the apneas and hypopneas being obstructive in nature. Home sleep apnea testing (HSAT) will also be accepted, with RDI 5-60, with greater than 75% of the apneas and hypopneas being obstructive in nature.
* Should be getting at least 6 hours of sleep nightly.
* BMI between 18.5 and 35

Inclusion Criteria for participants with OSA who have CPAP intolerance:

* Symptomatic, with polysomnography (PSG) showing AASM AHI 5-60 and symptoms attributable to OSA, with greater than 75% of the apneas and hypopneas being obstructive in nature. Home sleep apnea testing (HSAT) will also be accepted, with RDI 5-60, with greater than 75% of the apneas and hypopneas being obstructive in nature.
* Attempted nightly use for at least 2 weeks (at least 12/14 nights), with average use \< 4 hours, and difficulty tolerating PAP during a titration study, with complaints of difficulty breathing with CPAP or other difficulties that are not clearly related to identifiable causes (claustrophobia, mask discomfort, untreated RLS, untreated mouth leak, poor sleep hygiene, drug use, etc.).
* Must be able to breathe through their noses comfortably while awake.
* Able and willing to do daily swallowing exercises (15-30 minutes per day) for a total of 14 weeks.
* Able and willing to use a positional therapy device to avoid supine sleep and to adjust their CPAP device settings (instructions will be provided).
* BMI between 18.5 and 35
* Not actively undergoing bariatric treatment or planning to start bariatric treatment within the next 6 months.

Exclusion Criteria for all participants:

* Presence of symptomatic swallowing disorders, neuromuscular disorders affecting the upper airway, or neurodegenerative disorders.
* Co-existing sleep disorders such as narcolepsy, untreated restless legs syndrome, circadian rhythm disorders, or behavioral insomnia/poor sleep hygiene.
* Clinically significant congenital or acquired anomalies or history of surgery on the head and neck, excluding adenotonsillectomy, turbinate reduction, and septoplasty. Participants who had a tongue tie release outside of the newborn period will be excluded, but those who had tongue tie release in the newborn period will be eligible.
* Known complex sleep apnea or a history of conditions that are associated with the development of complex sleep apnea, such as heart failure, atrial fibrillation, a history of stroke, or opioid use.
* Prescription or nonprescription stimulant use (excluding caffeine).
* Substance use disorder or nightly alcohol consumption, as these significantly interfere with normal sleep.
* Current unstable illness (such as asthma, hypertension, cancer, etc.), kidney failure with restrictions on fluid consumption, or unplanned hospitalization in the past year for an ongoing condition.
* Risk factors for harm from expiratory strength testing and training: history of spontaneous pneumothorax, presence of CSF drain, recent trauma involving head, neck, or chest, history of recurrent epistaxis, history of esophageal surgery, active or recent hemoptysis, history of lung transplant or lung resection, eardrum rupture or any other condition of the ear, uncontrolled gastroesophageal reflux, abdominal hernia or recent hernia repair, urinary or fecal incontinence, presence of aneurysm (such as cerebral or aortic).
* Participants with CPAP intolerance only: Latex allergy in themselves or household members (due to balloon use in exercises).
* Allergy to Micropore paper tape (used in home sleep testing and for participants with CPAP intolerance during 2-week CPAP trial and exercise intervention).
* Pregnancy, actively trying to get pregnant, or sexually active and not using birth control (for people of child-bearing potential).
* Has a condition that increases the risk of developing cancer, such as BRCA1/2.
* Does not speak English fluently.