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A Question of OA duration. - mdh235 - 09-21-2013
I apologize in advance if this has been covered. I was unable to find it using the Search feature of the site.
Anyway, while reviewing my sleep data I noticed that my OA events were often over 30 seconds long. Is this normal?
From the ResMed Interpretation guide it appears there's a 10 second lag between when the machine recognizes the OA then tries to correct it. Still 20+ seconds still seems like a long time to me.
I keep my ResMed Autoset S9 in a range of 11 - 13 and my EPR at 2.
If anyone has any insight/suggestions, I'd appreciate hearing them.
RE: A Question of OA duration. - Sleepster - 09-21-2013
You have to stop breathing (actually just reduce your breathing by some fixed amount) for 10 seconds before it's considered an apnea.
30 seconds may seem like a long time, but there are other things to consider as well. How many of these events are you having per hour, and are they occurring when your pressure is maxed out at 13?
RE: A Question of OA duration. - mdh235 - 09-21-2013
(09-21-2013, 02:54 PM)Sleepster Wrote: You have to stop breathing (actually just reduce your breathing by some fixed amount) for 10 seconds before it's considered an apnea.
30 seconds may seem like a long time, but there are other things to consider as well. How many of these events are you having per hour, and are they occurring when your pressure is maxed out at 13?
Just two last night in 8 hours, and no, my pressure was at the base level.
Still, when I see those red spikes reaching skyward like skyscrapers it worries me some. I imagine that 30 seconds is enough to trigger my brain to wake me up, which I thought PAP was supposed to stop.
Still very new at this, but since I'll be living with this the rest of my life I'm trying to learn as much as I can so I can manage my own therapy.
Thanks for the response.
RE: A Question of OA duration. - Sleepster - 09-21-2013
Having that happen only twice in one night is awesome.
Yes, it's true that these events could cause arousals and interfere with the quality of your sleep.
Keep in mind, though, that if you have less than 5 events per hour you will not be diagnosed with sleep apnea.
It could be that your body is simply anticipating an apnea, something it's learned to do over the years. If I were you I'd wait and see what happens as you adapt to CPAP therapy. You should be very happy with the results you have so far. There are many people who would kill to have only two 30-second events in one night.
RE: A Question of OA duration. - archangle - 09-21-2013
By design, the S9 AutoSet doesn't try to stop an apnea while it's happening. It increases the pressure very slowly to try and stop the next apnea. Usually, it will only increase pressure 1 cmH2O per minute or so.
I believe all Auto CPAP machines work this way.
Some more complicated machines such as some bilevel, ASV, or ventilator machines may have a more immediate response. There are drawbacks to this, too.
The stock answer is that an occasional apnea doesn't do that much harm. It's not uncommon for someone to have an apnea that goes even as high as 200 seconds.
If it's a problem, the solution would probably be to increase your minimum pressure. It's a judgment call whether to increase the pressure and suffer the possible problems of pressure to eliminate a certain amount of apneas. Unless you've developed pressure induced central apnea, increasing the pressure would probably stop or reduce your occasional long apnea.
RE: A Question of OA duration. - mdh235 - 09-21-2013
(09-21-2013, 04:16 PM)Sleepster Wrote: Having that happen only twice in one night is awesome.
Yes, it's true that these events could cause arousals and interfere with the quality of your sleep.
Keep in mind, though, that if you have less than 5 events per hour you will not be diagnosed with sleep apnea.
It could be that your body is simply anticipating an apnea, something it's learned to do over the years. If I were you I'd wait and see what happens as you adapt to CPAP therapy. You should be very happy with the results you have so far. There are many people who would kill to have only two 30-second events in one night.
I should have been clearer. I'm only have the 30+ second events a couple of times a night. I'm having other OA events - maybe 1 per hour - but they're half as long.
Also, when I was diagnosed, my AHI was less than 7, so getting it down below 3 isn't quite the miracle that it may appear at first.
So my confusion is about why some events take twice as long for PAP to "fix" than others. If I had a real sleep doc I'd be bugging him, but unfortunately I don't. The doc who wrote my prescription is a pulmonologist who says he has no way to read my data card. For that I have to send it to the DME, who then sends a summary report back to the doc. Nobody is looking at the detailed data except me, and I'm a medical idiot.
I guess the bottom line here for me is simply is my machine working correctly?
Thanks for the help. I've learned more here in a month than in the previous six months of sleep studies.
RE: A Question of OA duration. - me50 - 09-21-2013
We have to have someone on our side that we feel is watching our results from CPAP therapy. I don't feel comfortable with just the opinions of the RT at the DME's office. I have been told by some that having 8 events per hour is okay with and some say only 5 per hour is okay with them. I want mine as low as possible per hour, but, there is more to it than just how many per hour. They should watch what kind it is, how long it lasts, etc. etc. and I don't think that we always get that kind of monitoring from the DME. I would think that the DME would download the info and send it to your pulmonologist and they should be able to review the report and if they can't or won't, look elsewhere! It is your life and they need to devote time to you when you are in the office paying for their services.
RE: A Question of OA duration. - Sleepster - 09-21-2013
(09-21-2013, 07:40 PM)mdh235 Wrote: I should have been clearer. I'm only have the 30+ second events a couple of times a night. I'm having other OA events - maybe 1 per hour - but they're half as long.
Still, that's great.
Quote:Also, when I was diagnosed, my AHI was less than 7, so getting it down below 3 isn't quite the miracle that it may appear at first.
It can make a big difference in the way you feel, in your cognitive abilities, and in a reduced risk of heart disease.
Quote:So my confusion is about why some events take twice as long for PAP to "fix" than others.
The literature from the manufacturer is misleading. The machine doesn't fix individual apneas as they happen by raising the pressure.
These events are not like a light that's either on or off. Our breathing waxes and wanes, and it's a judgement call as to whether or not we're having an event (apnea or hypopnea).
It's considered normal to have up to five of them per hour.
The data shows that your machine is successfully treating your condition. If I were you I'd celebrate.
RE: A Question of OA duration. - mdh235 - 09-21-2013
(09-21-2013, 09:01 PM)Sleepster Wrote: The data shows that your machine is successfully treating your condition. If I were you I'd celebrate.
Oh, I'm happy. I'm certainly feeling better overall than before CPAP. I just want to understand what's happening better.
RE: A Question of OA duration. - PaulaO2 - 09-22-2013
It could be the extra long events happen when you are on your back. The machine has to fight gravity, then.
And we also have to accept that sometimes we aren't going to know what happened and why. But that's okay. You know how to look at the data and how to see what is normal and what is not - in terms of YOU.