That is why home sleep testing offers so much promise. While over 20 million Americans have sleep apnea, it is estimated that approximately 80% are undiagnosed. Meanwhile, OSA is a known risk factor for stroke, cardiac arrest, respiratory distress, congestive heart failure and even sudden death. That doesn't even address the most common side effect of obstructive sleep apnea, namely snoring which strains many a marriage or relationship. So, anything that can make it easier and less expensive to test for OSA and get patients the treatment they need can literally save lives.
Are Home Sleep Testing Monitors Effective?
So, there's a lot of promise but do home sleep testing monitors actually work and are they just as effective as a full blown polysomnography test? The answers are very well and most of the time depending on the type of home sleep testing monitor used (more on that later). Home sleep testing monitors use the same type of diagnostic tools to measure blood oxygen, respiration, body position and movement as those used in PSG testing so they generally are just as accurate. However, since the test is conducted at home without supervision or assistance, it does require and depend upon the skill and follow though of a person that is usually not trained (e.g. the patient) so mistakes do occur and tests do sometimes have to be repeated over several nights to collect accurate data. It's also important to note that there are four different classifications for sleep study monitors (1-4). Not all sleep monitors measure all the same types of functions so depending on what type of monitor you are using, you may not collect enough data to allow for a definitive diagnosis.
Types of Home Sleep Testing Monitors
As noted, there are 4 different classification for sleep monitors. Type 1 monitors are those used in sleep apnea clinics and they require a qualified sleep technician to oversee them so they are not relevant to this discussion of home monitors. We will focus on type 2, type 3 and type 4 home sleep testing monitors as they are portable devices used in home sleep testing.
Type 2 home sleep testing monitors are the most powerful portable monitors and measure all the same body functions or channels as the type 1 devices. Type 2 monitors record data for a minimum of 7 different channels including heart, brain (EEG), eye (EOG), movement, respiration, blood oxygen saturation and airflow.
Type 3 home sleep testing monitors measure from 4 to 7 (typically 4) different functions or channels usually including 2 respiratory functions such as respiratory movement and airflow as well as cardiac function and blood oxygen saturation. Some type 3 monitors also can detect snoring and body movement. While type 3 monitors can be effective, since they do not measure eye movement or brain waves, they are not capable of detecting REM disorders, sleep stages, sleep arousals or sleep position and they tend to produce lower AHI (Apnea-Hypopnea Index) scores that PSG tests.
Type 4 home sleep testing monitors traditionally only measured one or two channels such as blood oxygen or airflow. However, in the United States, after the Centers for Medicare and Medicaid Services(CMS) mandated that a home sleep testing monitor must track at least 3 functions or channels to qualify for reimbursement, the standard was changed. So, type 4 monitors now usually measure blood oxygen, airflow and a third channel such as body position and/or snoring.
How Home Sleep Testing Monitors Work
Home sleep testing monitors work by measuring different body functions or channels. To measure airflow, they may use a nasal cannula or nasal prongs to detect airflow through the nose as well as an oral thermistor for measuring airflow from the mouth. Pulse oximeters measure the level of oxygen in the blood, a critical factor in determining the presence of OSA. An ECG measures the heart rate while chest and abdominal belts are used to measure respiratory effort. This is important to distinguish between the struggle to breathe characteristic with obstructive sleep apnea vs. the absence of breathing effort common with central sleep apnea. Leg movements may also be monitored through the use of small leg straps. Snoring is usually monitored by placing a small microphone on the neck. Sometimes a special nasal cannula may be utilized to monitor airflow pressure since snoring also causes it to increase and this can be measured and used to indicate when snoring occurs.
Using a Home Sleep Testing Monitor
Using a home sleep testing monitor is easy. While they usually require a doctor's order, many are available through the mail with easy to follow setup and instructions. Some even auto score the results when the testing is complete. Others require that you mail it back and have the results interpreted by a qualified sleep professional. Your doctor may have one in his/her office and demonstrate its operation for you. Don't be afraid to ask questions.
If you are having sleep problems and you have any of these symptoms: waking up exhausted, daytime sleepiness, waking with a morning headache, you snore, you have increased irritability, depression or high blood pressure and you are overweight, these are common side effects of sleep apnea indicating you may have obstructive sleep apnea. It's important to talk with your doctor and discuss your symptoms because sleep apnea is grossly under-diagnosed and the health impacts are significant. Your doctor may recommend you get a PSG test. Talk with him/her and see if you are a candidate for home sleep testing. If you are, you'll find it's less intrusive, costs less and is more convenient than a traditional sleep study. If you think you may have sleep apnea, don't wait. Talk with your doctor and see if you are a candidate for home sleep testing.