Central vs Obstructive Sleep Apnea

[JerryL]

I've read about this on the cpaptalk.com wiki, but I'm still confused. Most of the things I have read seem to say that OSA and CSA are caused by two completely different things: OSA is caused by blockage in the breathing pathway, while CSA is caused by one's brain "forgetting" to breathe. So I had expected that they were unrelated -- if someone had both of them, that would be coincidence. (Just as if you had a broken leg and bronchitis -- there's no reason you couldn't have both, but they have nothing to do with each other.)

I just had a full sleep test. Two nights: the first night checked me for apnea, and then much later, they put a CPAP on me and checked my titration levels. I now have a doctor's prescription for a CPAP machine.

But I made sure to ask for a full copy of my sleep study report. And it says:

Non-REM sleep: 252 minutes. Apnea/Hypopnea Index (AHI) = 13.1.

• 15 central apneas. (Mean duration 24.6 seconds. Index 3.6.)
• 18 obstructive apneas. (Mean duration 22.9 seconds. Index 4.3.)
• 5 mixed apneas. (Mean duration 35.8 seconds. Index 1.2.)
• 17 hypopneas. (Mean duration 34.8 seconds. Iindex 4.0.)

REM sleep: 17 minutes. Apnea/Hypopnea Index (AHI) = 74.1.

• 9 central apneas. (Mean duration 19.3 seconds. Index 31.8.)
• 4 obstructive apneas. (Mean duration 25.8 seconds. Index 14.1.)
• 7 mixed apneas. (Mean duration 37.0 seconds. Index 24.7.)
• 1 hypopnea. (Mean duration 25.0 seconds. Index 3.5.)

Total Sleep Time: 269 minutes (4.5 hours). Apnea/Hypopnea Index (AHI) = 17.0.

• 24 central apneas. (Mean duration 22.7 seconds. Index 5.4.)
• 22 obstructive apneas. (Mean duration 23.4 seconds. Index 4.9.)
• 12 mixed apneas. (Mean duration 36.5 seconds. Index 2.7.)
• 18 hypopneas. (Mean duration 34.3 seconds. Index 4.0.)

The number of my central apnea events is very close to the number of my obstructive apnea events, and their mean durations are similar. Does this mean that I have both central and obstructive apnea? Or am I misunderstanding what it means to "have" apnea?

Ever since I was a kid, I sometimes stop breathing -- often when I'm reading a book. I don't do this on purpose, and I usually don't notice it, but every now and then I suddenly inhale and realize that I haven't inhaled for a while. I was very thin until I was about 30 years old, but now I'm somewhat overweight (5'10" male, 220 lbs, BMI 31.4); I don't know if that's a relevant fact. For some reason I have always been nervous that I have central apnea, and worry that a CPAP machine will make things worse rather than better! Is this an irrational fear?

The sleep study diagnosed me with "moderate" OSA, and in the follow-up study they found a pressure that eliminated "most of the events causing arousals."

[jnk...]

During a PSG, in simple terms, an obstruction is when you are trying to breathe but can't, and a central is when you momentarily aren't trying to breathe when all indications are that you should be. PAP therapy can often help both of those situations.

If your machine has the ability to record efficacy data, then you will know if centrals continue to occur in concerning numbers so that you can have that looked at more carefully by your doc. But if the centrals go away or are greatly reduced once your airway is sufficiently stabilized for a while (which in some cases takes many weeks), then the unstable airway is what is considered to have been the root cause of the problem that led to the numerous centrals too.

As a general rule, very broadly speaking, obstruction is a simple physical issue to be corrected with a simple physical fix (PAP); whereas, a concerning amount of centrals may be a symptom of some other issue that may or may not be addressed sufficiently by PAP. Time is needed to tell. And in the context of home treatment machines, having a few centrals reported to us now and then doesn't matter, since it can be natural for some of us to have some unstable breathing when going from one stage of sleep to another.

The key thing to understand when doing research is fully grasping the difference, in context, between (1) the occurrence of a single central sleep apnea and (2) the diagnosed condition of central sleep apnea, in which many centrals persist. It is easy to confuse the two and to read them as the same thing when first doing research. So, if you research (1) the phenomenon of having a single isolated central sleep apnea (never a big deal), don't get thrown by the hits that come up on (2) the diagnosed condition of central sleep apnea (which may be a symptom of other deeper issues).

Please ask further questions if that answer doesn't clear things up for you.

[Julie]

If you actually have central or even mixed apnea, you're likely to get a different version of a regular Cpap (or Apap) machine that deals with those (and also addresses the obstructives), but without more info, like seeing a Sleepyhead report, you can't know for sure yet what you really have - many so-called 'centrals' end up being seen mostly when you're just falling asleep and/or waking, with few through the night, and are therefore known as 'sleep-wake junk' that can be ignored. With your REM situation, again, Sleepyhead would help us to further learn what's really going on and come to a better conclusion and advise you. Oh, and how you breathe (or not) when awake is not relevant - breathing patterns are different when sleeping and you shouldn't try to include awake ones (especially those of a young person immersed in exciting stories ) as the machines won't recognize or react to them in a useful way.

[Pugsy]

Is the sleep study results you posted above the diagnostic sleep study without cpap or is it with cpap and mask and machine being used?

Do you take any medications of any kind? If so, what?

[jnk...]

. . . in the follow-up study they found a pressure that eliminated "most of the events causing arousals."

[JerryL]

Is the sleep study results you posted above the diagnostic sleep study without cpap or is it with cpap and mask and machine being used?

Do you take any medications of any kind? If so, what?

These numbers are from the first sleep study, without any CPAP. I have the numbers from the second sleep study, with CPAP titration, but the format of the output is totally different, and there is no information about central versus obstructive.

I take pills for cholesterol (Atorvastatin/Lipitor) and acid reflux (Omeprazole/Prilosec), and vitamins. Those are my only meds.

To be honest, my main concern is this: I am unemployed and my insurance is Medi-Cal (the California version of Medicaid). That means every single step of this has taken multiple referrals and long waits; my first request for a sleep study was last summer! The sleep study folks were nice but gave me almost no information. They sent their paperwork directly to my ENT doctor. The ENT doctor, while very nice, doesn't inspire me with much confidence, and he told me almost nothing: he just said "You are getting a CPAP machine; I have submitted the prescription." He didn't give me any paperwork, and even the prescription is done through Medi-Cal.

So I called his office and asked the receptionist for a copy of the sleep study results, and she mailed them to me. But to be honest, I think the folks on this forum seem to know much more about apnea than my ENT doctor.

[JerryL]

If you actually have central or even mixed apnea, you're likely to get a different version of a regular Cpap (or Apap) machine that deals with those (and also addresses the obstructives)...

That's what's supposed to happen. But my ear-nose-throat specialist sees Medi-Cal patients, and every time I visit him, his waiting room is packed. There are even people standing in the corridor outside his suite, because there isn't enough room in his waiting room. People wait an hour to see him, and then he sees them for a couple minutes. I don't blame him: Medi-Cal reimbursement rates are so low that this is probably the only way he can make a living (which is why most doctors don't accept Medi-Cal patients). But it makes me worry: what if he simply took two seconds to say "Apnea? CPAP machine!" without thinking about the possibility of central sleep apnea?

My titration study tested the CPAP machine at different pressures: 4, 5, 6, 7, 8, and 9 cm H2O. The AHI for each of these were, respectively, 3.3, 10.2, 13.0, 3.5, 17.0, and 2.8. So they concluded that the best pressure is 9 cm. The total test lasted 203 minutes (I thought it was longer than that!), and the portion at 9 cm was 69 minutes, so that seems to be a good sample. However, for some reason I had no REM sleep during the 9 cm portion of the test! (During the 8 cm portion, I had a lot of REM sleep.)

[Julie]

First - you are entitled to all paperwork on your record by law.

Second, is there a reason (I lost track of why you're not scheduled to use an Apap vs plain Cpap? It would make treating you more effective and following up, tweaking things, etc. better.

Stay with this thread please - easier to keep track of... Good luck!

[JerryL]

Second, is there a reason (I lost track of why you're not scheduled to use an Apap vs plain Cpap?

See my last post. Nobody told me much. At the end of the second sleep test, the lady woke me up and said "I gradually increased the pressure until I found the one which makes your apnea vanish." The pressure she was referring to was 9cm. The paperwork from the sleep study says, "Recommendation: CPAP with humidification at 9cmH20 through a Standard six ResMed AirFit N10 Nasal mask should be initiated."

One thing that seems odd is that they didn't try any pressures above 9cm. I know they don't want to use a higher pressure than is needed, but is it normal to not even test higher pressures during the titration test?

And should I be concerned that there was no REM sleep during the 9cm portion of the test?

The nasal mask seemed much better than the one I tried ten years ago, when I tried CPAP for a week then gave up on it. But it's the only mask they tried on me, and I have no idea what the alternatives might be.

Nobody mentioned APAP -- I just learned about it when I read the wiki on this website.

Stay with this thread please - easier to keep track of... Good luck!

Thanks!

[JerryL]

Quick questions: During a sleep test, are apnea "events" and "arousals" synonyms? I know that an "arousal" means you come out of deep sleep, and I'm pretty sure an apnea "event" is when you stop breathing, so I wonder if these are related but distinct things.

What is the "index" that appears in the results? (See my first post above.) Is that the same as "arousal index", which this site defines as arousals per hour?

On my second sleep study, there are columns for each different pressure during the test (4cm through 9cm). In this column, it gives the AHI and number of arousals. It also appears to list values for "obstructive, central, mixed" -- but these figures are all zero. So I guess they didn't distinguish these durign the test.

Here are the results:

4 cm H2O. (Total time: 203 minutes.)

• 73% awake, 3% stage 1, 16% stage 2, 8% stage 3, 0% stage 4, 0% REM.
• 0 = number of arousals.
• 0.0 = arousal index.
• 13 = number of snores.
• 14.3 = snore index.
• 3.3 = AHI.

5 cm H2O. (Total time: 35 minutes.)

• 0% awake, 0% stage 1, 65% stage 2, 35% stage 3, 0% stage 4, 0% REM.
• 3 = number of arousals.
• 5.1 = arousal index.
• 44 = number of snores.
• 75.0 = snore index.
• 10.2 = AHI.

6 cm H2O. (Total time: 9 minutes.)

• 0% awake, 0% stage 1, 0% stage 2, 51% stage 3, 0% stage 4, 49% REM.
• 1 = number of arousals.
• 6.5 = arousal index.
• 0 = number of snores.
• 0.0 = snore index.
• 13.0 = AHI.

7 cm H2O. (Total time: 88 minutes.)

• 3% awake, 1% stage 1, 35% stage 2, 47% stage 3, 0% stage 4, 14% REM.
• 6 = number of arousals.
• 4.2 = arousal index.
• 2 = number of snores.
• 1.4 = snore index.
• 3.5 = AHI.

8 cm H2O. (Total time: 35 minutes.)

• 0% awake, 0% stage 1, 47% stage 2, 0% stage 3, 0% stage 4, 53% REM.
• 2 = number of arousals.
• 3.4 = arousal index.
• 1 = number of snores.
• 1.7 = snore index.
• 17.0 = AHI.

9 cm H2O. (Total time: 69 minutes.)

• 9% awake, 0% stage 1, 33% stage 2, 58% stage 3, 0% stage 4, 0% REM.
• 5 = number of arousals.
• 4.7 = arousal index.
• 0 = number of snores.
• 0.0 = snore index.
• 2.8 = AHI.

Should I be concerned that the final category (9 cm H2O -- which is what they prescribed) didn't include any REM sleep?

Also, the comparison between the 8cm and 9cm category seems odd to me. Arousal index was higher for 9cm, but the AHI went way down. Is that logical?

[zonker]

But to be honest, I think the folks on this forum seem to know much more about apnea than my ENT doctor.

hi, jerry and welcome to the forum. i see you are in good hands and i have nothing really to add.

EXCEPT, the bit i quoted above. as you continue through your journey, you are likely to find, more and more, that the people here know much more than the doctors!

[Julie]

Yes, events are apneas (here, anyhow) but not all are arousals which awaken you to some extent, whether or not you realize it.

AHI - apnea/hypopnea index - made up (mostly, usually) of obstructive apneas and wannabe ones called hypopneas - shorter and less damaging - partial obstructives.

For more 'glossary' stuff, look at the lightbulb at the top of the main pg - lots of good info, but ask whatever you want here anyhow (some of that stuff may be a bit out of date too).

I'm not the best interpreter of all those results but they look pretty good - someone else might get more definitive about them...

[Pugsy]

See if RobySue's blog clears up some confusion about some of the terms.
http://adventures-in-hosehead-land.blog ... -test.html

With your insurance situation....you will have no choice but to start with basic cpap most likely and hopefully you will get a machine that can flag centrals and obstructive apneas separately so you can keep a watch on the central situation.

[BTS]

See if RobySue's blog clears up some confusion about some of the terms.
http://adventures-in-hosehead-land.blog ... -test.html

With your insurance situation....you will have no choice but to start with basic cpap most likely and hopefully you will get a machine that can flag centrals and obstructive apneas separately so you can keep a watch on the central situation.

It is true, it is a long very long stressful process.. I am coming from that exact thing ... Complex Apnea starting with basic CPAP all the way up to ASV ruling out each xPAP treatment first to even be considered for funding with the proper machine to treat me.. I am now the 3 weeks into ASV treatment and waiting on approval with funding.. The machine has been a life saver getting my numbers way down under 5 from 95 ... Still such Hell getting to this point .. it's a fight but worth it to have this machine covered, they are not exactly cheap ..and it's not just getting to ASV the DME tries to off old bricks old versions of machines to the ones not in the know.. It's worth the research on what you want and what will best treat you and don't get taken advantage of ..

Edit: I think I got a little ahead of myself here, just read the other posts .. I see you're not even close to this point yet but I'll leave it up anyways ... Wish you well..

[JerryL]

Thanks, everyone! I am supposed to pick up my machine and mask tomorrow. I'll let you know what happens.

I'm not the best interpreter of all those results but they look pretty good - someone else might get more definitive about them...

They look "pretty good" in what sense? just curious!