Diagnostic criteria for obstructive sleep apnea

By Tracy Latest Activity September 26, 2010 at 12:18 pm Views 12,373 Replies 8 Likes 4


How is apnea diagnosed? What are the doctors looking for? What is the difference between mild, moderate and severe sleep apnea?

All good questions. Hope the following information is helpful!

Sleep apnea is diagnosed using an overnight sleep study called polysomnogram.
During the study a lot of data is collected including respiratory air flow, blood oxygen saturation levels, heart rate, muscle activity of legs and chin, sleeping positions, eye movement and the electrical activity of the brain.

The severity of sleep apnea is determined using the AHI or Apnea/Hypopnea Index, also referred to as the RDI or Respiratory Distress Index. This is the total number of apneas plus the total number of hypopneas, divided by the length of the sleep period. An easy way to think about this is how many times per hour do we stop breathing during sleep!

An apnea is the complete cessation of breathing for 10 seconds or more, and sometimes can even last over a minute.

A hypopnea is an episode of reduced airflow (usually by one-third or more) often accompanied by a drop in oxygen saturation and/or a measured arousal in the brain.

AHI or RDI is usually expressed as a number per hour. While standards vary, an index of 10-20 is considered Mild, 21-40 Moderate, and anything greater than 40 is considered Severe Apnea. Anything over 5 is considered abnormal.

Symptoms vary but include snoring or gasping noises preceeded by silence ( the cessation of breath) disturbed or restless sleep, unrefreshing sleep, daytime sleepiness, or other daytime symptoms such as memory loss, inability to concentrate, low libido, headaches.


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Replies (8 replies)

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  • Kathy Cook
    Kathy Cook December 9, 2010 at 9:50 pm   

    My C-Pap says NOT to use anything but distilled water. It can damage the machine.

  • caraelena
    caraelena October 2, 2010 at 6:47 pm   

    I just had my sleep study last night. My family practioner suspected I had apnea and now it has been confirmed. I haven't gotten my prescription yet and now I'm scared to go to sleep tonight. They told me this morning I stopped breathing over 100 times! I am happy they did find this. I have struggled with fatigue for years and this is probably why. Now I have a chance at a whole new life. I'm glad I have this site to help guide me through this process.

  • kitterykid
    kitterykid September 27, 2011 at 4:49 pm   

    You can use Distilled or Spring water.

  • Tracy
    Tracy December 9, 2010 at 10:34 am   

    so do you have your cpap equipment now? How is that going for you? Let us know if you are having any difficulties with mask or machine, we are here to help!

  • David G.
    David G. October 21, 2010 at 11:28 pm   

    When I had my test about 4 years ago they claimed I would stop breathing for sometimes up to 38 seconds!! Yikes! I use my machine now every night, though I stopped using the humidification unit that came with it. Expensive for distilled water, and I got used to the waterless one. Don't have too much dry mouth problems. My biggest disappointment is that I thought I would feel a tremendous burst of new energy. I've felt some, but nothing like I was hoping. Guess I'll have to work harder on the weight loss, which will probably help alot.

  • Tracy
    Tracy December 9, 2010 at 11:00 am   

    Hi David;
    Distilled water is the best choice - I buy the big gallon containers at the grocery store for about a buck! I have poor water quality at home, so cannot use tap water. Just wanted to let you know that using tap water means you might see mineral deposits collect in the water chamber. They might appear as a white or even a pink film or powdery lookiing. To remove and disinfect, fill the water chamber with 1/2 vinegar and 1/2 water - let soak for about an hour, then rinse with clear water. Should result in a sparkling clean water chamber!

    good sleep…

  • TheDreamer
    TheDreamer December 10, 2010 at 2:59 pm   

    Personally, I got a water distiller. Walking the 1.5 miles up hill back from the grocery store is painful enough without the extra weight carrying non-instant distilled water.

    Plus I had worked out at the time…based on how much the grocery store was charging for distilled water, and the cost of electricity for a run and the cost of the machine…that break even would be about 3 years.

    I actually use more distilled water now than when I started (nasal rinse and drinking it when I get up thirsty during the night)…though the price of distilled water at the grocery store has dropped, etc. So, break even is still about the same point.

    Don't forget that even if you use only distilled water, to clean out the water chamber once in a while. While stays clean longer, the air that's blowing past it isn't clean and drops gunk into the water which came develop into nasty stuff. I neglected my tank for a few months during the summer, and discovered it was pink with floaties… I opted to replace the tank, though more because I had a spare already on hand.

    The Dreamer.

  • Anonymous
    Anonymous October 4, 2010 at 9:42 am   

    I'm glad you found us too!
    It is a good feeling knowing FINALLY what the problem is - now you must get to the therapy. While you are waiting for your cpap equipment, try to avoid sleeping on your back. Most of us with apnea have the greatest number of apnea episodes when we sleep on our back - think gravity! So side or stomach sleep - if you must sleep on your back, use a couple of pillows to elevate yourself.

    When time comes for mask choice…make sure you take an active role in picking out the best mask for your face. You must try them on and while hooked up to the cpap machine blowing at your pressure. Remember too, a mask fits and feels totally different when you are standing up in a showroom - so when trying on masks, some places have an area where you can actually lay down. If not, ask if you can sit next to a desk and then lay your head to the side as if you were laying on your bed pillow.

    Ask if your provider has a 30 day mask exchange program - many do these days - it allows us patients to take a mask home to trial and then if it does not work, you can exchange it for another.

    Lastly - when you get your cpap machine - be sure to have them educate you on all of the patient controlled comfort features so you will know how to adjust them if necessary…these might include ramp - cflex - EPR

    Looking forward to hearing more from you - and again, welcome to sleep connect.
    Think positive!

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