Doc says no APAP, could cause centrals?

[datara]

I have a Respironics System One auto, I asked my Doc about using APAP, he said to just use it as a CPAP (Which is fine) but said that using Auto could induce central events, does this sound right?
At 8 cm I am down to AHI 5.2, I thought that perhaps using Auto might bring me even lower. I am confused , is apap not better?

Thanks,

Datara

[redjoe]

I use my machine on auto, and have almost no central apneas.

[cowlypso]

Just because it's more technologically advanced doesn't make it "better."

Auto mode is great for doing in-home titrations. You set it wide-open and watch what happens. From there, you can get a good idea of the ideal pressure. Auto mode is also useful for people who have significantly different pressure needs when sleeping in different positions. The machine can respond and increase the pressure when they roll over onto their backs.

Some people use auto mode all the time, although most often at a reduced range. A person might set the range for 10-16, or something like that. If you generally need a minimum pressure of 10 to keep your airway open, then there's no sense in setting the starting pressure at 4, because it will take the machine longer to respond to events and increase pressure to a therapeutic level. There's also no sense in leaving the upper limit at 20 if the machine never goes above 15 (although there is less harm in leaving the upper limit high than in leaving the lower limit low).

Some people are sensitive to pressure changes in their sleep and wake up when the machine increases the pressure. These people do best on straight CPAP rather than auto mode.

Another reason to stay with straight CPAP is to avoid central apneas. However, the new machines can distinguish between centrals and obstructives, and won't raise the pressure for a central. And, honestly, you are at risk of centrals with straight CPAP too. The difference is that, wtih straight CPAP, you are at one pressure and know how you will respond at that one pressure. With auto mode, the machine might take you up to a pressure range that does induce centrals. Then again, staying with straight CPAP and increasing the pressure can also induce centrals.

Are centrals bad? Sort of. Certainly you don't want to have tons of them. And it's not at all abnormal to have some centrals when you are falling asleep. So if you have 1 or 2 in a night, no big deal. Some sleep doctors seem inordinately afraid of them.

Funny conversation I had with my doctor about centrals: I was asking about why, at my sleep study, they didn't try raising the pressure another step, since at the highest pressure they reached I still had an AHI of 6. The doctor said that it's dangerous to go too high on the pressure because it can cause centrals. Then she recommended that I increase my pressure because I was still having symptoms. Her recommendation was to go from 8 to 10. I asked why it was too dangerous for them to go up by 1 in the sleep lab with supervision and monitors, but safe to go up by 2 at home with none of that, and she had no good answer...

I did end up going up to 10 (straight CPAP). Then I wondered if maybe I could back down on the pressure a bit. I set my machine to auto with a range of 8 to 12 for a few days. My AHI went up, which is to be expected, since you have to have events for the machine to respond and increase the pressure. Once I saw that the top pressure the machine reached on auto was 9.6, I set my machine on straight CPAP at 9.5. I might try lowering it by .5 again soon, and see what it does to my AHI. For me, though, I would not run my machine in auto mode regularly, because my AHI did go up by more than double (mainly because it was so low to start with on straight CPAP). Since I get better results using straight CPAP than auto mode, I don't use auto mode.

With your AHI at 5.2, there is definitely room for improvement. Are you still having symptoms? If you've been on the machine for a few weeks (always wait at least a week or two between changes) and you've eliminated leaks, then it might be time to try a pressure increase to see if that helps.

[LinkC]

I, too, use my APAP in CPAP mode most of the time. I get better numbers.

To answer your question, yes, APAP can induce centrals if not set and/or monitored properly. Your doc is assuming you can't or won't do that. And it sounds like he doesn't want to be bothered, either...

[BrianinTN]

is apap not better?

I wouldn't call it "better" or "worse" -- just different. Some people do better with straight CPAP than they do with APAP. Others (especially those with positional apnea) often benefit from the flexibility of APAP.

As posters above me noted, your doctor is technically correct; APAP can induce central apneas. Whether it actually does is very patient-specific.

For us to really comment on your situation, it would help if we could see some pages of your nightly data. If your current AHI consists largely of obstructive apneas, it may be the case that your current pressure is too low for part or all of your sleep. However, if you are very early in your therapy, I would suggest giving it a little more time to see how things shake out.

[archangle]

Remember your doctor is a trained professional and we're anonymous amateurs on the internet. Of course, that doesn't mean he's right.

Increased pressure is thought to sometimes cause centrals. Auto pressure can "run away" and increase your pressure to where you get more centrals, so your doctor is not "wrong."

Be glad he's not one of the idiots who simply give you an auto machine set to 4-20 auto and never bothers to look at the data and check the results. There's also some value in "starting small" in your treatment.

Also, be glad you got a good machine that records data and can be used to check up on how your treatment is actually progressing. You have an excellent machine. A lot of people get stuck with stupid machines that don't record any apnea data by uncaring, greedy, or dumb DMEs and doctors.

I'm not convinced that "auto" always finds the right pressure. I think my machine would settle in at a lower than optimum pressure in auto mode, leaving me with some symptoms. Luckily, I can simply set my machine to have the minimum pressure at this "optimum" level so it never drops below this level. I leave my maximum auto pressure at 20 and haven't yet had any problems with the pressure running away on me.

By the way, how long have you been doing CPAP, and how often, if ever, has your doctor or DME asked you to bring in the card and checked your results?

Instead of using auto, it may be possible to try small pressure increases and see what happens to your numbers.


However:

1) Auto pressure can be set to a fairly narrow range. For instance, setting your range to 8-10 auto would do you no more harm than simply trying a pressure of 10.

2) If you get the software and monitor it, you can check to see if your auto pressure is running away, and you're getting centrals. Doing this right requires more than a "once every x months" visit to the doctor. It also requires the doctor or someone to have the software, and take the time to understand and use it. I don't think "runaway" pressure is really all that common.

[Pugsy]

I use APAP. 10 cm minimum and 20 cm maximum pressures. It suits my needs because in REM sleep I sometimes need upwards of 18 cm. Pressure changes have never bothered me. When not in REM sleep I stay around 11 to 12 cm.
On the times I have seen much higher pressures I have not seen an increase in centrals. So while pressure increases can cause centrals it doesn't happen to everyone. Pressure induced centrals are not all that common.

[Janknitz]

Some of us need a range of pressures to address varying conditions during the night--it might be that we spend part of the night on our backs or it might be that apnea increases during REM sleep. But that doesn't mean we have wide open pressure ranges. For most of us that do best on auto, our pressure range is dialed in so that it is most effective for us.

Too much pressure, whether from straight CPAP or an auto setting that is too high, may cause centrals in some individuals. But those of us who use APAP settings--whether because we need it or prefer it--don't have centrals all the time because of it.

So the answer is--yes, an APAP can cause centrals, but if you are properly titrated and the range is set correctly, you probably won't have centrals.

Remember, most doctors do not trust us to self-titrate correctly, and they often don't want to expend the time and effort to work with you on this if a straight CPAP setting is working well enough.

[GumbyCT]

As mentioned it is not the auto but the increased pressure that 'can' cause central events to happen. Auto works for me but may not work for others. I wouldn't go w/o my auto.

Did you get a copy of your sleep study? Did any centrals occur during your titration?

I had straight cpap for many months as my first machine. IF you can't exhale against a pressure (17) is that a central? IF you have no data on your machine, how can you tell? You can't.

An auto was my first relief, I felt much better when I could exhale part of the nite
An auto is also good for those who don't need a high pressure ALL nite long.
A BiPap is the ultimate in exhale relief therapy.

So it is not the auto that causes central events. In fact, one can have 'Centrals' without Pap Therapy. Having centrals vs obstructive events is not any better or worse than the other. That fact there is no O2 exchange IS indeed a problem. You need to read your sleep study report.

[LarryD]

I don't understand how APAP's can cause CSA's. Is there any scientific info out there?

[datara]

Thanks to all for your very informative answers, I am noticing a huge difference my overall condition (went from 79.6 supine, and worse on my back down to a fairly consistent 5.2). I have soo much more energy, I just thought if I can improve on that, WOW. I think I'll track another couple of months on my new machine as I've only had it a couple of nights, I checked my average after I posted and it is stating 3.3 at this point.

Datara

[BrianinTN]

I don't understand how APAP's can cause CSA's. Is there any scientific info out there?

It's not the APAP so much as it is the pressure. You'll find the condition commonly referred to as "complex sleep apnea" -- referring to patients being treated with CPAP for obstructive apnea but who have central apneas that emerge in response to that treatment. There are hundreds of papers on the subject, with varying opinions on how serious those central apneas are and how likely they are to subside with time.

[ozij]

I don't understand how APAP's can cause CSA's. Is there any scientific info out there?

Yes, there is.
Use your usual techinques for finding scientific info about other subjects.

[rested gal]

While this is not an answer to the specific question... do autopaps cause centrals? ... here are tons of discussions that might help for those who want to learn about central apneas:

Links to Central Apnea discussions
viewtopic.php?p=22702

[Guest]

we're anonymous amateurs on the internet.

Great point. There is a LOT of misinformation in this thread. Caveat emptor.