Sleep Doc Visit - How are centrals detected?

[DreamDiver]

I visited with the sleep doc Thursday after the titration study. I told him how the pressure pulse from the omnilab advanced kept waking me up. I also showed him that even at 9cm pressure (as suggested by the outcome of the titration) was still throwing as many centrals as when it was at 10.4. He said my machine was not as complex as the study machines they use in the lab and that the data from them is not as reliable. My wife said "So, if the S9 is not that reliable, then when a Respiratory Tech from your sleep lab looks over the data from the S9, your saying that's not reliable?" I think that flustered him. He avoided answering the question. He also avoided answering any questions about how centrals are detected in the lab. I half expected this, I guess.

He suggested that I put away all the data review and just try 'being normal', not Einstein. He's taking the approach that I'm stressed out about stuff and that I should 'take a vacation' and chill out. Do what I want to do. Hmmm... Don't have a full-time job. Don't have any money to go on vacation... I already do what I want to do. I'm not that stressed out. I'm just in pain and brain fogged. He gave me a prescription for clonazepam, .5mg to take at bedtime. I am familiar with this drug, as it is similar to diazepam - which was about the only thing in the past that has been successful in relieving my generalized pain. This med is very much lower dose though, so the effects are even more subtle without noticeable side effects - yet. Works for me. So I started taking that. We don't see eye to eye on the reasons for taking it, but the overall outcome of the visit is that I will stop watching my data for a few weeks, take the clonazepam and 'chill out'. But still...

Let's say there's the equal possibility of opening 'the box' and finding Schroedinger's cat in the box either eating a kitty snack or not eating a kitty snack -- because I don't like equating myself to the original example. I feel like he's seeing me as that instance of Schroedinger's cat he would like the experiment to turn out to be - not the actual cat or it's true outcome. He says things like I look more relaxed than the last time he saw me. I actually felt neither more nor less relaxed. About the same - tired. He's not willing to explain to me how centrals are actually detected. I wonder if I need a new sleep doc.

While I haven't been looking at my data since talking with the doc, my S9 still shows clear, unobstructed airway during all apneas for the several days prior to my visit with him at the new suggested setting, cpap mode. My understanding is that obstructive apneas have something blocking the air column. When I look close up at the difference between a what the S9 calls an obstructive apnea as opposed to a central apnea, I can deduce just by looking at the waves whether the airway is open or blocked. The method used at the sleep lab is obviously vastly different from that used by my machine to detect patency. I can see truth in what I see in my S9 graphs with regards to patency. If I stop breathing for ten or more seconds and the airway is clear, FOT and COS are clearly legible in the graph. On the few occasions when I have had obstructives, COS was clearly absent and the apnea is marked as obstructive. The data is fundamentally unflawed and high resolution. It's hard to miss. If that isn't an indication of clear or obstructed, I don't know what is. Obstructive is closed. Central is open. Right?

If someone could help me understand: I would like to know exactly what process they use to determine what determines the difference between obstructive and central (unobstructed) sleep apnea in the lab. I know it has something to do with the two bands around my trunk, but other than that, I'm clueless. A simple definition still leaves me clueless. It's clinicalese, devoid of information on the instruments and methods used. I could use a picture. I've seen just about every Resmed and Respironics video -- they tend to gloss over the technical details to be useful for this kind of explanation. But if there is a sleep lab video out there that explains exactly how it's measured, that would be great.

The S9 method is like shining a sonar depth detector down my windpipe. In essence, it's a real-time, 4.33Hz, one dimensional 'view' of my windpipe -- a depth guage, so to speak. Without meaning to seem puerile, I'm skeptical. Until someone can prove to me what constitutes patency in current sleep lab detection practice and why it's more valid than the waveform detection used by the S9, I'm skeptical of the current accepted method of lab detection. I request for someone to prove to me why the sleep lab's methods are better than FOT -- why the S9's patency detection is less trustworthy.

[ozij]

A central apnea is scored when:

• You are not breathing
• And no breathing effort is observed in your chest and abdomen

And of course, you have to be asleep/

The Resmed has no way of recording your effort to breathe, or lack of it, therefore, whatever is scores as a central apnea is less reliable.

Furthermore, the sleep lab can identify your sleep state -- it will not score apneas when you are awake or tossing and turning. The Resmed does not know your sleep state.

Trying to convince a doctor that your machine scores better and more reliably than a sleep lab is a lost cause. You can -- and should -- put an emphasis on how disrupted you sleep was by the lab's technology, how unrepresentative your sleep in the lab was of your normal sleep. I'm surprised the two of you did not discuss a repeat sleep study. Seems like preferred to focus on having the doc. diagnose you based on your machines data. A good doctor will accept your reports of how you sleep - and possibly your machines data -- as important information in his decision making -- but not as replacement for the tools he relies on. Any attempt to have him rely solely on data from a machine he does not necessarily know is futile.

The way you tell it, your doc preferred to shut you up with a clonazepam rather than explain things.
However, the following is your own statement:

I'm just in pain and brain fogged. He gave me a prescription for clonazepam, .5mg to take at bedtime. I am familiar with this drug, as it is similar to diazepam - which was about the only thing in the past that has been successful in relieving my generalized pain.

Not sure whose initiative it was for you to take Benzodiazepines again. Are you hinting the doctor Rx-ed it because he thinks you have an anxiety disorder, and you accept it because it's a solution to your physical pain?

Have you ever sought a specialist's advice for your generalized pain?

I spent a few months of constant muscle pain recently, discussed it with my GP who promptly decided to test my vitamin D -- and I turned out to have very low levels of it. It did not enter her mind to prescribe a tranquilizer -- and I would have yelled bloody murder of she did.

[Muse-Inc]

I'm with you on this one DD...the S9 data is just plain amazing! I wouldn't trust the data from that equipment as the 2 cmH2O 'puffs' would sure cause arousals if not wakeups...that would skew results, thus affect any proposed therapy. However, Ozij makes some great points about IDing sleep stages/arousals...just a shame the equipment does that. If that had been my initial sleep study I'd have never fallen asleep with the equipment.

I forget, what are your SpO2 %s like?

[dsm]

Both POVs have real value. As Ozij suggested, the lab uses the 'effort to breathe' as the real test. And also as Ozij pointed out they will discount tossing & turning CAs.

But the S9 is one big advance over anything we had before. And, as you (DD) have already shown us, you can read the breath-by-breath waveforms & apparently very accurately deduce what is taking place with your breathing. We have come such a long way in recent times. What we need next here is an AI program that can analyse the data & make educated suggestions as to the probability of the activity.

But, future tech aside, there are 2 very helpful things we can do at home - 1) is using an SpO2 (such as the very high res Nonin 3012 (which samples in the millisecs) & use it to determine if the events are benign or bad - 2) is reading our data such as that data that can be extracted from the S9. It seems unlikely we will ever have an attachment that can measure effort-to-breathe but I am in little doubt that some forms of motion detector might be able to be used in a way that comes close. We have already seen the work going into sleep brain wave analysis available today.

Cheers

DSM

[DreamDiver]

Thanks ozij, Muse-Inc, dsm for your replies.

I agree that some apneas are waking apneas and thus should not be scored. Those area easily discarded. However, respiratory effort should be easy to see in the wave form of an open airway. There would be small spikes in the flow -- which would consequently shorten the apnea being sensed, as the machine wouldn't score anything where breathing has resumed before ten seconds. I've seen this many times in my flow graphs -- several subapneas in a row with tiny breaths in between. No score. During rem sleep, at periods in the middle of the night, these are definitely centrals. Just moving or turning over causes a change in flow that registers in the wave form. So should respiratory effort. The suggestion that it cannot be measured in flow seems spurious.

My whole body moves to the beat of my heart at night. The chest cavity pulses. It's enough to make the bed move. We used to have reading light clipped to the head of the bed with a little angel pendant dangling from a chain. We changed sides of the bed because when I sleep on the other side of the bed, it causes a little 'creak' sound to the rhythm of my heart beat, and the angel pendant would swing in time. The whole bed would visibly move to my heart rhythm. I have an antigravity chair that's very comfortable to sit in that also bobs to my heart beat. I wonder if this body 'habit' is in any way screwing with the results of those stupid bands.

I was not hinting at the doc for meds if that's what you mean. I do think he thinks it's about anxiety. I got the diazepam last time from a visit to the campus doc whose specialty was sports medicine. At the time my arm was severely cramped. I'd thought I'd broken it or something. She said they sometimes used diazepam as a muscle relaxer. Yes, every doc thinks I'm stressed out. I think they're confusing 'intensity' for stress. I just figured if he's looking for a label for insurance purposes, he's going to do what he's going to do, no matter what I think. I can play along until I find a doctor who's willing to listen. Still haven't found one yet.

For generalized pain, I have been to rheumatologists, dermatologists, neurologists, psychiatrists, all suggesting one method or another for pain remediation - or fobbed me off to the next specialist. I generally cannot take most drugs because they give reactions that are unexpected, unpleasant or weird. Diazepam was the only one I could take last time, but I could only use it once in a while because it would cause monster crazy dreams if I took it very much. Actually, the dreams would start out really cool, but then with continued use became more and more gruesome and ominous. Clonazepam seems to be heading in the same direction. Meditation was fine for a while but now the brain fog is so bad, it's like trying to breathe in gnat-infested air, all the time feeling like you're about to fall asleep. Every little thing grabs my attention -- almost like ADHD. My heart is still doing the 'funky chicken' (or the 'flip-flopping carp') mostly at night. Leg, foot and chest cramps continue on a random basis whenever I stretch too hard or move in a funny direction. (This used to happen to my dad too, but only after he took a course of an anti-cancer drug called vincrystin, known to make extremities go numb and cause the cramping.) I get on these coughing jags that make me see stars. It sounds like I'm going to cough my lungs out. I get hives here and there on my arms and trunk for no apparent reason that then just as mysteriously resolve. As you know, I lost my sense of taste (but not sense of smell or tactility of the tongue) for several months last year, but now it's back. Various unexplained physical maladies come and go. Twice to the doctor two years ago for unexplained anaphylaxis. We still don't know the cause. You may imagine I hate prednisone, but for the first two days of the course, I actually feel like a normal person. No headaches, no tinnitus, no pains. 'Able to do the dishes in a single stand. Woohoo.' Then the crummy side effects settle in just as the course ends, and I'm glad to be rid of it, and the pain returns.

I really think there's more going on here than any one doctor is willing to look at. I keep getting the doctors who say their tests show everything is well, they can't help me -- maybe I should try a doctor from a different specialist. Then my GP retired. So now, I'm going to go to a new GP next week. I don't know if this is going to work. He'll likely send me to a bunch of other doctors who will all tell him there's nothing wrong with me, it's all in my head, I'm stressed out, get some rest, take a vacation... I need one doctor who isn't afraid to look at the results of a test and question them... who can look at a brain scan and understand it as well as the scoring of a sleep study or any other data thrown at him... one who can review symptoms and not rely just on test numbers as the dogma of the religion of science.

The medical profession has become for me purely a method of extracting money from my wallet until I am out of resources, only to start up again when I have more resources. Nobody should live in this kind of physical pain on a constant basis. Meditation for pain remediation should not take a major part of the day -- nor should sleep. I'm getting pretty good at coping with it using these methods, but I think if the docs had to put up with it themselves, they'd find some reason pretty darned quick as to why it's happening. Since they can't feel it and they only allot fifteen minutes for accountancy purposes, it's not they're problem. I'm fobbed off to the next specialist.

To top it off now, I've got some sort of rhinovirus coming on, so I'm a bit cranky now.
There are times when I'd like to see that machine and mask sail out my window. This would be one of them.

I agree that I think I need re-titration where there are actual apneas to score. I'm not sure it will make a difference if the machinery cannot tell for real whether it's respiratory effort or just my body throbbing like normal. It's not that I don't trust machines. I don't trust that they're always correct, as apparently most doctors do.

[echo]

Sheesh, the doctor/specialist run-around. There's no one these days that wants to look at the WHOLE person and all the symptoms.

Do you perhaps have some strange mold growth anywhere in your house? That could be causing some of the symptoms you report, and the mold-food allergies connection is also very strong. Could be in the walls, behind the paint/wallpaper, in the bathroom, behind the toilet, in the kitchen, .....

I'm sure this has been discussed, so sorry to ask again, but have you had an in-depth exam with a cardiologist? That heart beating just doesn't sound normal. Enlarged heart, CAD, a blockage in the aorta...?

[DreamDiver]

Sheesh, the doctor/specialist run-around. There's no one these days that wants to look at the WHOLE person and all the symptoms.

Do you perhaps have some strange mold growth anywhere in your house? That could be causing some of the symptoms you report, and the mold-food allergies connection is also very strong. Could be in the walls, behind the paint/wallpaper, in the bathroom, behind the toilet, in the kitchen, .....

I'm sure this has been discussed, so sorry to ask again, but have you had an in-depth exam with a cardiologist? That heart beating just doesn't sound normal. Enlarged heart, CAD, a blockage in the aorta...?

My current sleep doc's first specialty is cardiology. The second thing we did was a full ECG. Other than one slightly enlarged ventricle from sleep apnea and mild tricuspid regurgitation (which apparently shows up in 80% of the population anyway), I'm - of course - healthy.

Escaping mold in Georgia is an exercise in futility. Once we went on vacation to Tybee. We were going to stay at a supposely fancy hotel that cost an arm and a leg. When we got there, there were quarter-sized pocks of mold covering the ceiling. The door to our room was obviously recently broken into. The air conditioning was obviously not functioning correctly. We left immediately and called a local B&B. No mold. It was lovely and cost two-thirds what we would have spent. However, we've done the best we can - and I think successfully - to keep our home dry and mold-free inside from attic to crawlspace. Bone dry.

I'd still like to know exactly how they decide that breathing effort is observed so that it indicates central or obstructive apnea. What combination of graphs from the band and some other flow indicator are they using to show one or the other? What wave forms are recognized in what combination to mean one or the other? Why is it better than the S9 method?

[gpk111]

DD,

Sorry to hear your so frustrating situation. A couple of thoughts:

1. My sleep doc has a lot of faith in sleep labs (which I questioned, since it's only a snapshot of a single point in time), since he says he can interpret the data to isolate extraneous data. However, when I pointed out to him that the average pressure on my S9 was two units lower than recommended by the sleep lab, he responded that he was much more comfortable with the longer term S9 data than the snapshot form the lab.

2. Have you seen a pain doc or three (in South Florida, a lot of them seem to be set up to sell drugs for resale). If you find a good one, that may shed some light on things.

Gerry

[BeanMeScot]

Do you know where the pain is coming from?

[oscar98]

DD, I don't know if this link will answer your questions or not but if was an interesting read. http://www.daveburrows.com/cpap/sleepst ... pstudy.pdf

If I read it correctly they decide it is central apnea when the belts around your chest and abdomen show no effort to breathe during the apnea. According to this during an obstructive apnea the effort to breathe (chest movement) is there and during a central there is not effort to breathe.

I found that link on this page posted/created by someone here but I don't recall who. http://www.osahelp.com/

[JohnBFisher]

DreamDiver, sorry to hear you are having fun. However, I also agree with Ozij. It is MUCH more important to stress the symptom than the data. If any of us present data from our machine we should present it as more along the line of a windsock. We can see the direction and general strength of the wind. But it just is not monitoring enough to be conclusive. But it definitely can provide an indication ...

... I'd still like to know exactly how they decide that breathing effort is observed so that it indicates central or obstructive apnea. What combination of graphs from the band and some other flow indicator are they using to show one or the other? What wave forms are recognized in what combination to mean one or the other? Why is it better than the S9 method? ...

Well, the EEG leads provide an indication of the stage of sleep. The bands about the abdomen and chest record the breathing effort. If the technician observes an apnea and there is NO breathing effort and you are actually asleep, then it is scored as a central apnea.

Of course most of this is automated at this point, but as I understand it, the sleep test scoring is confirmed by the sleep tech as well your sleep doctor.

So, when do you have central apneas that would be counted by the S9, but not during a sleep study? Let's say your pain is enough that it disturbs your sleep. You awaken (though you might not remember it - more on that in a moment), and you start to fall back to sleep. During that transition to sleep central apneas are normal and should / must be ignored. But the S9 would have no clue that you were awake and falling back to sleep.

Now, you might be wondering if you would remember being awake. I can assure you that if the time is minimal (a matter of minutes) most of us completely forget those periods. In fact, prior to diagnosis, I had a job that required me to be "on call" to handle system issues. I would get called on a weekly basis. I had NO memory of the calls (still don't). But my wife would ask me questions about the calls. Yikes! Some people remember those short periods of wakefulness better than others. My wife does. I do not. And every time I would fall back to sleep central apneas would be perfectly normal.

Of course, I am not dismissing that you might have problems with central apneas. I had that happen to me for years. My neurologist finally admitted I probably should have been on an ASV unit years ago. You might reach a time when you need to change doctors.

But if you change doctors, do so because the SYMPTOMS are not being addressed, not because the S9 data is not being addressed.

Hope that helps.

[DreamDiver]

Same thread - new post - same topic.
I just came back from a new visit to my sleep doc.

We don't get along. I'm looking for a new sleep doc.

He admitted that he is a clinician and isn't interested in finding out whether the chest bands were incorrectly measuring cardiac oscillation as thoracic movement, primarily because the sleep center he runs isn't the one that did the study because his lab isnt' set up yet to accept BCBS.

I've gotten a DVD of all the data from the lab, but I can't read it. To top it off, there was some kind of gook on the readable surface of the dvd that I had to polish off carefully so my dvd player could actually read see the files. So they don't provide a free reader, and edf browser won't work with this data. The data was recorded with xltek hardware/software from an omnilab advanced xPAP.

What can I use to read this data? Surely there is a free reader out there for this stuff.

Muffy, if you're listening, I could use your advice.

[sleepmba]

DD,
I work in a sleep center and do sleep studies. The software you speak of is very expensive. The companies that write the software protect it from piracy because they want to make money (of course). The only thing you can do is give the CD to your new sleep doc and he/she can look at your study only if they have XLtech. The report from the sleep study is more valuable than the data itself.

The effort belts you were mentioning can only measure the expansion and contraction of your chest and abdomen when you are breathing. They call these movements "effort".

The explanations of central apneas vs obstructuve apneas provided so far are very good. I'll try to say it in another way... With an obstructive apnea, you are still trying to breathe, but there is a "clog" in your airway preventing airflow. With a central apnea, you are not trying to breathe at all.

If you have anymore technical questions, I'll be happy to answer or blog about it.

[DreamDiver]

DD,
I work in a sleep center and do sleep studies. The software you speak of is very expensive. The companies that write the software protect it from piracy because they want to make money (of course). The only thing you can do is give the CD to your new sleep doc and he/she can look at your study only if they have XLtech. The report from the sleep study is more valuable than the data itself.

The effort belts you were mentioning can only measure the expansion and contraction of your chest and abdomen when you are breathing. They call these movements "effort".

The explanations of central apneas vs obstructuve apneas provided so far are very good. I'll try to say it in another way... With an obstructive apnea, you are still trying to breathe, but there is a "clog" in your airway preventing airflow. With a central apnea, you are not trying to breathe at all.

If you have anymore technical questions, I'll be happy to answer or blog about it.

sleepmba,

Thanks for your reply.

I am assuming there is a scoring algorithm that a sleep tech verifies, but doesn't necessarily evaluate effort manually. Is this correct?

My chest moves with cardiac oscillation, enough that it actually rocks the bed at home at night. If I sit in an antigravity chair, much the same happens, but even more pronounced. I don't snore and never have. As I've said before, the S9's FOT is basically a one-dimensional depth gauge, giving me a fair assessment of patency. I still don't see how attempts to measure chest effort can give an accurate measure of patency. I mean, that's what we're measuring, right? What makes band effort more accurate than a true measure of patency with what amounts to a sonar depth gauge (FOT)?

I suspect that the effort bands are measuring cardiac oscillation and that whatever algorithm xltek is using to automatically score 'effort' is merely scoring the cardiac feeback oscillation of my thorax/chest and not true effort.

I wonder if the scorer expects to see certain things and saw what s/he expected to see and wasn't looking for anything irregular, relying heavily on what the scoring algorithm provides as proof without further verification. "Next patient..." I suspect this happens a lot. How far am I from being wrong?

What I don't get is why xltek doesn't make a reader they can give docs and patients who want to just read their data.

[Big Daddy RRT,RPSGT]

You monitor the heart and pulse rate so you can differentiate between cardiac ocillations and respiratory effort in the sleep lab.

We ignore normal central apneas that occur while awake and also ignore brief post arousal central apneas that do not cause desats or additional arousals, an auto pap unit will count these as central apnea events in your reports.

Pain/sedating meds can cause central apneas, maybe this is the problem?