CPAP to test for sleep apnea

[nvanderhoeven]

My husband has sleep apnea and we purchased a Resmed AirSense 10 for him. However, we still have his rental CPAP (a Philips Respironics One + Philip Wisp nasal mask) and since we're paid up until next week, I thought I would take the opportunity to test myself on it. My father had sleep apnea and I'd like to find out whether I have it too, but I'd rather not pay for a sleep study since I don't (yet) have any symptoms.

I thought of setting it to a lower pressure, but 6 cmH20 was the lowest pressure I could stand while awake, and I read on this forum that even 5 cmH20 could already be sufficient to stop apneas, thus masking them from the results. So I went the other way and set it to auto last night from 6-20 cmH20. I slept for 3 hours. My AHI was 0.33, but my 95th percentile pressure is 10.9 with my max at 13. Is it normal for the pressure to increase even without apneas? Or did I really stop breathing and the machine had to increase the pressure to keep me breathing? What can I do to determine whether I have sleep apnea or not?

I was also thinking of buying a pulse oximeter, but I'd like one whose results I can view in Sleepyhead. What's a really good model to get for the purposes of testing whether I have sleep apnea and also helping finetune the settings my husband needs?

[rick blaine]

Someone whose been on this forum longer than I have will probably be along in a moment to explain to you that the algorithms in that Philips auto machine (and I am assuming it is an auto, since you don't say) responds as much to (a) snoring and (b) 'respiratory effort related arousals' (or RERAs) as it responds to hypopneas and obstructive apneas.

And it does this by increasing the pressure, a bit at a time, until the RERA pattern disappears. You can think of a RERA as an 'almost' interruption, or 'the first sign in the wind that a storm is, or might be, coming'. So in answer to your question, "Is it normal for the pressure to increase even without apneas?" the answer is yes.

But that doesn't mean you have sleep apnea. The textbook definition of that is 'more than five interruptions per hour' - an interruption being either (c) a 50 per cent closed airway (hypopnea) or (d) a 90 per cent closed airway (obstructive apnea) - and both lasting for 10 seconds or more.

This video tells you more:

https://www.youtube.com/watch?v=-gie2dhqP2c

[jgalichia]

I got my pulse oximeter on Amazon. http://www.amazon.com/CMS-Finger-Pulse- ... B00B8L8ZXE Great deal and it works perfectly with Sleepyhead. I connect it up every morning and it imports my oximetry data in a few seconds. Takes a bit getting accustomed to having it on your finger at night but otherwise it is very helpful in learning more about the impact of my breathing on my heart rate and SpO2 levels.

[Cardsfan]

Set the machine at the lowest pressure you can tolerate. See what results you get set at 5 or 6 all night. It may show you have apnea. On the other hand, it may be enough to treat apnea set at 5 or 6. I have moderate apnea (ahi 30) which is successfully treated at a pressure of cpap 5. The only thing you can confirm doing this is that you have apnea that is not treated at the lowest pressure.

[chunkyfrog]

If the expense of a laboratory PSG is too daunting, ask your doctor about a take-home sleep study.

[palerider]

What can I do to determine whether I have sleep apnea or not?

pull the data from it and run it through sleepyhead to see why your pressure went up to 10.

[palerider]

This video tells you more:

https://www.youtube.com/watch?v=-gie2dhqP2c

no machine, to my knowledge, response to 'reras' which are vague and guessed at at any rate.

really, the only thing I recommend out of what you said is the bit about the video.

[robysue]

This video tells you more:

https://www.youtube.com/watch?v=-gie2dhqP2c

no machine, to my knowledge, response to 'reras' which are vague and guessed at at any rate.

The PR machines (both System Ones and DreamStations) do respond to anything they score as a RERA by increasing the pressure.

I believe the new Resmed AirSense 10 AutoSets and AutoSets for Her also increase pressure in response to anything they score as a RERA.

Now one can argue that the criteria that the machines use to score a RERA is vague. But it's really no more vague than the criteria used to score a FL.

On the PR System Ones, a RERA is scored (instead of a FL) when there is evidence in the flow rate curve of increasing respiratory effort (i.e. there's some possible flow limitation shapes in the flow rate curve) AND the flow limited sequence of breaths ends with what looks like are recovery breaths (one or more sharp, large inhalations) AND the recovery breaths are followed by a return to a more normal looking sleep breathing pattern.

I'm reasonably sure that the Resmed algorithm for scoring RERAs is probably very similar.

[palerider]

This video tells you more:

https://www.youtube.com/watch?v=-gie2dhqP2c

no machine, to my knowledge, response to 'reras' which are vague and guessed at at any rate.

The PR machines (both System Ones and DreamStations) do respond to anything they score as a RERA by increasing the pressure.

I believe the new Resmed AirSense 10 AutoSets and AutoSets for Her also increase pressure in response to anything they score as a RERA.

Now one can argue that the criteria that the machines use to score a RERA is vague. But it's really no more vague than the criteria used to score a FL.

On the PR System Ones, a RERA is scored (instead of a FL) when there is evidence in the flow rate curve of increasing respiratory effort (i.e. there's some possible flow limitation shapes in the flow rate curve) AND the flow limited sequence of breaths ends with what looks like are recovery breaths (one or more sharp, large inhalations) AND the recovery breaths are followed by a return to a more normal looking sleep breathing pattern.

I'm reasonably sure that the Resmed algorithm for scoring RERAs is probably very similar.

if you have any documentation on respironics responding to reras with pressure increases, I'd be interested... as vague as they are about everything else, I'd be doubtful that such exists. even sleepyhead charts showing pressure increases without FLs Snores or apneas would be interesting.

as to resmed, the airsense 10 autoset manual says: "The AutoSet algorithm adjusts treatment pressure as a function of three parameters: inspiratory flow limitation, snore, and apnea." and says that it reports suspected reras: "RERAs are periods of increasing respiratory effort which are terminated by an arousal. Increasing respiratory effort will be seen as airflow limitation.These flow-based RERA events are logged and stored as summary and/or detailed data and can then be viewed in one of ResMed's patient management systems." note that it doesn't say "Flow Limitations" and they're quite careful throughout the manual to refer to "Flow Limitation" as a distinct thing, though i suppose that's open to debate.

[nvanderhoeven]

Here's the sleepyhead data from last night. I slept nearly 5 hours with it on auto from 6-20 and my AHI was 0.82. I'm inclined to chalk it up as proof that I don't have sleep apnea, along with not having any symptoms (no daytime sleepiness, minimal snoring only when I have allergies, no mental fog, no exhaustion in the morning). Reasonable or not?

[Cardsfan]

All it proves is that at pressure 6-20, you are successfully treated for obstructive apnea. Try setting at a straight pressure of 5 if possible, and see what you get. If you notice, the pressure does not stay at 6. So it is rising in response to prevent events.

[archangle]

Neither CPAP nor a pulse oximeter will prove you don't have apnea. However, they may "prove" you DO have apnea.

I don't have good data on the percent of false negatives they will give where someone does have apnea, but doesn't show it with a "CPAP test" or overnight pulseox test.

My best guess is that most people with moderate or worse apnea will show up on CPAP. I'm more skeptical about pulseox. If you are one of the people who "wakes up" enough to catch your breath before your O2 drops, you might not show anything on a "pulseox test."