Sleep Apnea Testing

Gretchen Becker Health Guide January 20, 2011
  • Most of us have a general idea of what sleep apnea is. It means you stop breathing during the night for short periods of time, often many times during the night.


    This means you don't get a good night's sleep, which can cause daytime sleepiness. But it can also cause even more serious problems such as high blood pressure and heart disease. Getting older increases your risk for sleep apnea, but the main risk factor is being overweight. And because many people with type 2 diabetes are overweight, many people with diabetes also have sleep apnea.


    Many people with sleep apnea snore, but not all snorers have sleep apnea.

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    If you can lose weight, the sleep apnea may go away, but losing weight is often difficult. Sleep apnea can be treated by wearing something called a CPAP (continuous positive airway pressure) machine, a mask that fits over your mouth and nose and makes sure your airway is kept open all night.

    Until recently, if your doctor thought you had sleep apnea, you had to spend the night at a sleep clinic, where you'd be wired up to machines that would assess your sleep. But recently, an Israeli company has come up with a sleep apnea test kit, called WatchPAT, so people can be tested at home, in their own beds, where sleep might be more typical than in a strange place.


    Last year, the Cleveland Clinic voted the WatchPAT one of the top 10 medical innovations for 2010.


    This is not something you would buy yourself. Instead, your doctor would buy the kit (about $5000) and various consumable products that go along with it. You'd take it home, use it overnight in your own bed, and bring it back so the information could be downloaded to the doctor's computer for analysis.


    I like trying new things, so when I was at the Cleveland Clinic Innovations summit last fall and the company that makes the WatchPAT, Itamar, offered me a free test of the system, I said, "Sure."




    The kit was pretty easy to use. Before you get into bed, you strap a device onto your wrist, put several sensors on your fingers, put another device to detect snoring and your sleeping position (prone, supine, or left or right sides) on your chest. You press the Start button just before you get into bed.


    I found the most difficult part was remembering to press the Start button. I was so exhausted and eager to sleep that I almost forgot!


    The next day I returned the kit and got a printout showing my results. You can see a sample report here.


    PAT is peripheral arterial tone, which they use along with various other parameters to determining the stages of sleep. ODI is the oxygen saturation index. AHI is the apnea and hypopnea index, a measure of the time you spend not breathing (apnea) and breathing less than normal (hypopnea). RDI is the respiratory disturbance index, meaning an arousal from sleep that follows at least 10 seconds of "increased respiratory effort" but doesn't meet the criteria for AHI.


    You really need a pulmonologist to interpret all the results properly, but I found them fascinating even without expert interpretation. I learned that I spent about 25% of the night in REM (rapid eye movement) sleep, 18% in deep sleep, and 57% in light sleep. I was exhausted after a full day of travel plus listening to medical talks, and it would be interesting to see if the sleep pattern would be different if I were worried about something, or spent the day in hard physical labor, or had a typical less-action-packed day at home on my farm, or had a glass of wine with dinner, or took an antihistamine for allergies (they make me sleepy).


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    The sleep patterns of several sample subjects are also fascinating. Some people seemed to stay in one stage of sleep for a long time. Others bounced from one stage to another more frequently. One took almost an hour to fall asleep. None of the samples "dropped right off." I thought I had because I was so tired, but the record showed it took about 20 minutes for me to go from Wake to Light Sleep, and another 10 minutes to go to Deep Sleep.


    Maybe someday sleep-study gizmos will be as common and as cheap as blood glucose monitors are today, and we could all experiment to find how to get the best night's rest possible.


    But for now, we'll have to get the studies through our doctors. Many insurance companies, including Medicare, will cover the cost of the WatchPAT (about $64) if the test is prescribed, although coverage varies.