Do you think you have obstructive sleep apnea? Perhaps you’ve taken a sleep apnea quiz online and realize you have several of the symptoms or indicators, like snoring, morning headaches, or excessive daytime sleepiness.
Maybe your physician has noted your likelihood for apnea based on factors like your BMI, neck circumference, cardiovascular health, or family history. It’s even possible your doctor or sleep medicine dentist has asked you to pre-screen for apnea using the STOP BANG questionnaire—a diagnostic tool that helps physicians screen patients for the probability of moderate to severe sleep apnea.
If you think you have sleep apnea, you may be correct. After all, about 22 million Americans are living with this health condition, according to current figures, and an estimated 80% of these cases are thought to be undiagnosed. You could be one of those undiagnosed cases.
So Why Take an Apnea Test before Pursuing Treatment?
Based on your experience of symptoms, you and your doctor may have a working hypothesis that you’re likely to have mild to moderate apnea, the type that would allow you to be treated with an oral appliance (sleep apnea mouthpiece) as a first-line therapy instead of the more intrusive CPAP.
Many patients see this diagnosis as good news: sleep apnea mouthpieces are generally much easier for people to adapt to than a PAP device, because they’re more comfortable and require significantly less upkeep and maintenance. You could start noticing better sleep after the first night, and the likelihood of needing adjustments to your therapy is minimal. Patients tend to respond very well to sleep apnea mouthpieces because they’re fairly comfortable and the lifestyle change is minimal. Compliance tends to be high.
As exciting as the prospect of using oral appliance therapy is, doctors and sleep medicine dentists don’t make assumptions and prescribe oral appliances based on symptoms, questionnaires, and probabilities alone.
While you may indeed have mild to moderate apnea that can respond well to oral appliance therapy (OAT), in order to design a treatment plan that will actually work for you and alleviate your symptoms, your sleep medicine team needs to verify a few key pieces of information using a sleep study or home sleep test:
- That you have obstructive sleep apnea (and not central sleep apnea, or some other breathing disorder);
- That your apnea is can be treated effectively with OAT; and
- That you don’t have other underlying sleep disorders contributing to your symptoms (because if you did, these will likely require treatment as well).
These three factors cannot be verified based on symptoms and screening questionnaires alone; sleep physicians need to gather data about your sleep itself in order to confirm apnea, categorize its severity, and rule out the influence of other factors affecting your sleep, such as periodic limb movements or unusual brain activity.
In this article, you’ll learn more about the reasons for a sleep study and the types of sleep studies available to you (attended sleep tests in sleep centers or home sleep tests which you self-administer using borrowed equipment).
The key takeaway for people who may have obstructive sleep apnea: using a sleep test to verify both the existence of OSA and its severity is critical to getting effective treatment.
If you were to skip testing and treat severe apnea with a therapy like OAT that’s designed for mild to moderate apnea, the treatment may be unable to keep your airway open, and you would not get the necessary benefits to your health.
Severity Levels of Apnea (Why a Sleep Study Is Necessary to Confirm Apnea)
If you are found to have OSA, this means you experience breathing events during sleep. These events are caused by an airway obstruction.
If you have mild to moderate OSA, your airway obstruction may be an upper airway blockage caused by loose tissue at the back of the throat or by the tongue falling backward during sleep. Gravity pulls this tissue back and creates a crowding at the back of the mouth/top of the throat that blocks the airway and stops you from breathing.
Oral appliance therapy can slide your lower jaw forward, creating more space. The added space can accommodate the loose tissue and tongue while still leaving room for you to inhale and exhale without interruption.
With severe apnea, however, you may also have a buildup of loose, fatty tissue in the throat itself, which can cause blockages further down the airway. Such blockages might not improved by creating more space in the back of the mouth. In these cases, positive airway pressure therapy is advised to keep the entire airway clear of obstructions.
Sleep studies and home sleep tests take the data about your sleep and use it to determine where you fall on the Apnea-Hypopnea Index (AHI). The sleep study counts how often you either cease breathing altogether (apneas) or see a significant slowing in your breathing (hypopneas). Your number of events per hour, on average, determines where you fall on the index. This classification helps physicians decide what type of treatment you need.
Using the AHI, obstructive sleep apnea is classified as follows:
- Mild apnea: 5 to 14 breathing events per hour
- Moderate apnea: 15 to 29 events per hour
- Severe apnea: 30 or more events per hour
If you are diagnosed with mild to moderate apnea (5 to 29 events per hour), you may be good candidate for oral appliance apnea therapy. Severe apnea may still require PAP therapy.
Your sleep medicine physician and dentist need to know where you fall on this index before they can work together to make a plan for your treatment. Your apnea classification also helps to establish a baseline for your treatment, so your doctor and dentist can measure your improvements after you’ve begun therapy. This number is important for both measuring your success and reporting your progress to insurance companies.
Types of Sleep Studies: Home Sleep Test vs. Attended Sleep Study
You need a sleep test before beginning apnea therapy; but what kind?
Depending on your symptoms, your health history, and your responses to the STOP BANG questionnaire, your physician may recommend either a Home Sleep Test (HST) you administer yourself or a visit to a sleep center for an overnight polysomnography, where your sleep is monitored by technologists.
The two options have overlap in terms of what they measure, but they do differ in significant ways. A Home Sleep Apnea Test is focused solely on diagnosing obstructive sleep apnea, and is thus more limited in the data it collects; a traditional, monitored sleep study in a sleep lab gathers more comprehensive information about your sleep, including brain activity.
Both tests provide results to your sleep medicine physician for analysis and diagnosis. Below is a brief overview of how each test works.
Home Sleep Apnea Test (Home Sleep Study)
Also referred to as an Unattended Sleep Study or a Portable Sleep Study, these obstructive sleep apnea tests can be self-administered in your own home over a period of one to three nights, using an HST kit provided by a sleep diagnostic service company. Home apnea tests are simpler versions of the overnight sleep study you’d take at a sleep center. They are designed specifically to diagnose obstructive sleep apnea only.
When taking the HST, you follow testing instructions provided with the equipment. You go to sleep wearing:
- a strap around your abdomen and chest, which measures your breathing effort (how hard your muscles need to work to pull in or expel air)
- a nasal cannula, which measures the airflow through your mouth and nose (indicating whether there may be a blockage)
- a pulse oximeter clip on your fingertip, which measures blood oxygen saturation levels (indicating whether you are able to take in enough oxygen; a further piece of data which can indicate an obstruction in the airway)
After the testing period is complete, you return the testing kit to the diagnostic company and they download the results and send a report to your sleep medicine physician. This report indicates the extent of your breathing difficulty, which enables your physician to make a diagnosis of mild, moderate, or severe sleep apnea.
If you have mild to moderate apnea and your sleep physician feels you’re a good candidate for oral appliance therapy, she or he will refer you to a sleep medicine dentist for an exam to evaluate you for a device fitting.
Why take a home sleep study?
One advantage of a home sleep study is that it is more convenient than traveling to a sleep center. If you live in a rural area far from a sleep center, have a disability that makes leaving home difficult, or are otherwise prevented from taking the time out to spend a night at a sleep lab, a home sleep test can be a good alternative. A second advantage, particularly for people without health insurance, is that the home sleep test is much less expensive than a traditional sleep study.
A recent meta-analysis shows that when prescribed and used correctly, the Type III home sleep test (the most common kind) provides results that are just as useful as those conducted in a sleep center. (2)
Attended In-Lab Sleep Study
Traditional polysomnography in a sleep lab gathers additional information beyond what a home sleep test can gather. With an attended sleep study, you’re hooked up to additional sensors that also measure and monitor:
- brain activity, which helps technologists check for the presence of another sleep disorder with roots in the nervous system, such as a REM sleep disorder
- limb Movements
- heartbeat and heart electrical activity
- respiration rate
- air pressure requirements (titration); if you have apnea requiring CPAP therapy, technologists can use this time to determine your necessary therapeutic levels
An in-lab study is monitored by technologists. A trained sleep technician watches you in real time as you sleep and reports any unusual or disruptive activity during sleep, such as sleep talking, sleep walking, or tearing off your testing equipment. The technologists can make note of these activities on the report provided to your sleep doctor. They can also make note of any behaviors or actions that indicate the potential presence of additional sleep disorders that would not show up on a Home Sleep Test, such as narcolepsy or sleep terrors.
Before beginning oral appliance therapy for mild to moderate sleep apnea, it’s imperative that patients be diagnosed with obstructive sleep apnea via either a Home Sleep Test or an in-lab, attended sleep study.
Apnea testing provides physicians and dentists with the data they need to determine the presence and severity of sleep apnea, so they can create a treatment plan that will be beneficial to the patient.
Sleep tests in a sleep center go beyond the results of a Home Sleep Test by collecting more data. The information they monitor can screen for the presence of any additional sleep disorders beyond the apnea that may be negatively affecting a patient’s sleep.
Contact Premier Sleep Associates today at (425) 698-1732 if you would like a consultation with one of our dental sleep medicine experts...this is ALL we do!