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Can sleep studies be wrong?
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shewhorn Offline

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Post: #1
Can sleep studies be wrong?
I just had another sleep study done in January. It indicated OSA. I have a feeling this is wrong. My ex-girlfriends have indicated that I do NOT snore (unless I'm sick) and, as I'm falling asleep I'm sometimes semi-aware of the fact that I've just exhaled and stopped breathing... it wakes me up, I gasp, take a few deep breaths, try and sleep again, rinse and repeat until I'm "asleep". Looking at the data over the past 2 months from my CPAP machine... the overwhelming majority of events are indicated as "clear airway". Only occasionally do I see an OA or a hypopnea indicated. Is it possible that my machine is incorrectly identifying OA events as CA events over 75% of the time?

The reason I ask... I either feel no different from pre-CPAP treatment after two months of use, or I feel worse (waking up more groggy, more tired during the day, less physical energy, mood is deteriorating).
03-03-2016 12:02 PM
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Sleeprider Online
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Post: #2
RE: Can sleep studies be wrong?
The sleep study with polysomnography is pretty accurate and uses multiple channels to confirm that OA consist of you being asleep, a lack of respiratory flow, and positive respiratory effort. When those graphs line up, there isn't much chance of mistake.

Studies have correlated CPAP data to polysomnography and found that CPAP machines do a pretty good job of properly identifying events, however there are a few problems. The CPAP machine cannot determine you are asleep, its flow sensors are in the machine, and while it can detect lack of flow, the pulse or pressure oscillation is not a substitute to finding respiratory effort.

Comparing CPAP to untreated sleep is another source of error. CPAP pressure will treat the OA, but will not stop CA, or can even cause it in some cases. The lack of perceived benefit from CPAP is not uncommon, but without looking more closely at your data or other health issues, it's hard to say why you are not feeling better. Snoring is a common indication of airway obstruction, but sleep apnea can occur without snoring. I wish you the best, but I believe the sleep study is probably correct. Why not ask for a copy of the detailed data and see if you can interpret it?

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03-03-2016 12:16 PM
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PoolQ Offline

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Post: #3
RE: Can sleep studies be wrong?
The machine you are using cannot treat CA's and since you are not having OA's It would be more likely that your OA's are indeed being treated. How many CA's are you having? Your setting are not real high so I don't think that the pressure is causing your CA's but we might look at that.

Very unlikely that the machine is misidentifying OA's as CA's

You show that you use sleepyhead, lets see some data and see if someone here can identify what might help.
03-03-2016 12:22 PM
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Possum Online

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Post: #4
RE: Can sleep studies be wrong?
To answer your question, anything is possible; however, sleep studies, when conducted in legitimate labs, are generally pretty accurate and can easily discern between OSA and CSA. The Resmed A10 also has a pretty decent algorithm for distinguishing between CA and OA's - it sends little pressure pulses during an apnea, and if the pressure pulses result in an increase in flow, the apnea is labeled 'central', if not then it's labeled obstructive.

If you truly have mostly central apneas, then the A10 may not be the best machine for you, as it is designed mostly to open the airway when it closes, and thus treat hypopneas and OA's. There are other machines that address centrals directly. I don't know much about those machines but they are worth looking into and/or asking your doctor about. As I understand, sometimes CSA is even treated with supplemental oxygen alone - again, worth looking into.
(This post was last modified: 03-03-2016 12:25 PM by Possum.)
03-03-2016 12:24 PM
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Mosquitobait Offline

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Post: #5
RE: Can sleep studies be wrong?
My suggestion is to get a copy of your sleep study (the raw data) and look at it. Also, make an appointment with your sleep doctor and report that you are DETERIORATING rather than improving. As mentioned, cpap can increase CA in some people. In addition, you may have another health problem involved. In my sleep study, there was no indication of RLS, but during my titration, the tech saw me repeatedly disturbed from RLS. Could be something like that was missed because it didn't occur at the time of your sleep study.

Also, I concur with others. You do not have to snore to have sleep apnea.
(This post was last modified: 03-03-2016 01:25 PM by Mosquitobait.)
03-03-2016 01:24 PM
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archangle Offline
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Post: #6
RE: Can sleep studies be wrong?
The CPAP measures your AHI while you're being treated. It should be zero, even if you have horrible apnea without it.

In practice, many of us still have some apnea while using CPAP.

You can also have bad apnea without ever snoring, although most of us apneacs do snore.

The in-lab sleep tests are usually pretty darn conclusive. If you stop breathing for more than 10 seconds while asleep, that's an apnea. You should get a copy of your report with AHI numbers.

What's your AHI numbers? Post a copy of your SD card if you're willing. There are instructions in my signature line.

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03-03-2016 02:36 PM
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Ed1101 Offline

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Post: #7
RE: Can sleep studies be wrong?
Now at day 25 on APAP. Before I started treatment, I woke up feeling fine and was not fatigued during the day. Since stating treatment, I usually wake up feeling worse than when I went to bed. Do not wake up any more than before - at least I am not aware of waking up more or less often. However, most often I feel less alert, somewhat fatigued, experience balance issues and with a slight headache.

See Other Comments for my split study result. Currently, AHI ranges from 0.83 to 5.7 - mostly stays in 2-5 range. I have vanishingly few OA, mostly H and CA. CA seem to come in clusters 5-10 min after take a bathroom break - two mask off per night. I suspect that I am still awake but I do return to sleep quickly (8 min from lights out in diagnostic Sleep Study). 95% leak is around 15. Pressure is 15-17. I think I do not breath in a regular pattern when awake. I become aware that I am holding my breath for some unfathomable reason. Seems like in anticipation ... of what I do not know! Wish I could tell on charts when I am awake or asleep.

My wife tells me (and Doc) that I run out of breath when talking. For all these years I though that was normal. Spiro tests show moderate obstructive lung problem. Doc prescribed inhaler treatment once per day.

So maybe one does not alway feel better with CPAP treatment. But hopefully it will prevent a major heart event ... waking up feeling worse is far better than the alternative.

It does not matter how slowly you go as long as you do not stop. --Confucius
(This post was last modified: 03-03-2016 05:25 PM by Ed1101.)
03-03-2016 05:19 PM
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Gyddyup Offline

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Post: #8
RE: Can sleep studies be wrong?
am i right is suggesting you could fix your machine pressure at 5 for a night and see what's reported?

i'm guessing a pressure of five won't treat most apnea's, but the machine should pick up all events and give you an idea of what's probably happening without therapy.
03-03-2016 06:03 PM
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shewhorn Offline

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Post: #9
RE: Can sleep studies be wrong?
Thanks sleepyrider. I have a follow up appt in April so this is all helpful in figuring out what questions to ask. I suppose (since I'm relatively new to this) I'm also trying to gain a sense of "what is normal".

(03-03-2016 12:22 PM)PoolQ Wrote:  How many CA's are you having?

Last night the AHI was 8.14 over 7 hours, 37 minutes but... the CA events are heavily clustered. One of the clusters was 21 per hour, another 2 clusters averaged out to 13ish per hour. That's always how they seem to occur as well, in dense clusters.

Quote:You show that you use sleepyhead, lets see some data and see if someone here can identify what might help.

Here's a 1 hour segment of the most dense cluster from last night:
[Image: 25hd5zp.jpg]

And here's the full view of last night:
[Image: m2dfl.jpg]

Thanks Smile
03-03-2016 06:09 PM
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shewhorn Offline

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Post: #10
RE: Can sleep studies be wrong?
(03-03-2016 05:19 PM)Ed1101 Wrote:  Since stating treatment, I usually wake up feeling worse than when I went to bed. Do not wake up any more than before - at least I am not aware of waking up more or less often.

I'm definitely waking up more often. I used to wake up only once to use the bathroom if that... now I'm waking about about 4 to 5 times a night. I suspect these clusters would correlate with waking up which makes sense. When I zoom all the way in to that cluster I posted (top image) there's 6 large leaks which is probably me sticking my finger up the mask to scratch my nose after waking up.

Too bad these *PAP machines don't have a SMPTE timecode input or output... I could sync the results up with video. Smile
03-03-2016 06:25 PM
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