challenging the diagnosis of sleep apnea

[DannyCPAP]

I am diagnosed with sleep apnea.I noticed that my sleep doctor received from the sleep lab only a summary data of the night test, and apparently,to his surprise, some of it was actually missing. Although the lab produces a lot of data, most of it is not at all received by the diagnosing doctor and is analyzed only by the lab technicians.

I am using the ResMed S9 Elite machine. I am downloading the night data from the machine to their software and able to monitor my night sleep this way. My AHI is less than 5 and the machine reports mainly central events and almost zero obstructive events.

I am trying to make sense of my apnea diagnosis and what I see from the machine, so I have several questions that hopefully someone can answer:

1) How reliable is a CPAP machine in differentiating between central and obstructive events?
2) Is a CPAP machine of any use for central events or is it helpful only for obstructive apnea?
3) regardless of the type of events, if the AHI is low enough (say 3.5 on average), is there any need to use a CPAP machine?
4) many of my events (central) are recorded before I actually sleep. They occur during the 5 minutes ramp up time of the pressure and shortly after. Then, usually there is at least one hour before the next event. These events (while I am awake) are counted by the machine toward the AHI score. shouldn't they be ignored as non relevant?
5) many events are overlapping large swings in the leakage and are preceded by momentary increases in the flow. What is the possible relation between these three measurements?
6) many events (central) are recorded before I wake up (I am taking off the musk at night if I wake up, so that the machine will record the event). however, before the apnea event, I can see in the flow and leakage that I become restless many minutes before. I therefore assume that these events are recorded when I am at least half awake. do such events require a different treatment approach then events during real sleep time.
7) I also noticed that if I am restless when I go to sleep, I have more apnea events and wake ups. I am semi-successfully using meditation techniques now to relax the mind and the muscles before going to sleep. anyone has experience in the relation between relaxation and apnea?

thank you

[greatunclebill]

most of us went thru denial, but regardless of how you rationalize it and justify it to yourself, you have sleep apnea. the doctor would not prescribe and the insurance would not pay for a cpap if the sleep study justification were not sufficient. do not put your gear on e-bay just yet. i'm sure someone will give you a detailed answer to each question.

[Pugsy]

2) Is a CPAP machine of any use for central events or is it helpful only for obstructive apnea?

True centrals are not treated with pressure from a cpap machine because the airway is already open. It can't hold something open that is already open. The cessation of air flow is not from a collapse of the airway.
A few centrals here and there are no cause for alarm.
A large number of centrals merits a different diagnosis and a different type of machine that will actually blow enough air like a ventilator would.

3) regardless of the type of events, if the AHI is low enough (say 3.5 on average), is there any need to use a CPAP machine?

A low AHI while using the machine just means the machine is doing its job. The events that are shown are the ones that sneak past the machine's defenses. It doesn't flag the ones that it prevented.
If your AHI was 3.5 WITHOUT using a machine..obviously no need to use a machine but an AHI of 3.5 while using a machine only means that the machine did a good job and only allowed 3.5 events per hour to happen. We have no way to know how many events are actually prevented.

1) How reliable is a CPAP machine in differentiating between central and obstructive events?

Actually very reliable within the limitations of the machine. Like you already know..it doesn't know when you are awake or not. It doesn't have access to EEG brain waves for sleep stages.
While obviously not perfect...at least we have an idea what is going on...prior machines for years offered zero idea as to whether we were having centrals or not.

The machine calls them like it sees them. If you know you are awake you have to manually toss those numbers out of the equation. If your AHI is 3.5 total...that is very good and really doesn't warrant removing any awake events to evaluate the night...it is already good enough even with any awake events in the numbers. Would just maybe look better to your mind but there is no critical need to get the AHI "exact" by subtracting any awake events.

If you use SleepyHead you can isolate the time that you think you for sure are awake and manually get a reconfigured AHI.
Only seems to be available on the ResMed machines.
I explained how to do it in another thread. I will see if I can find it and edit this post with a link to that thread.
Give me a few minutes...I have lunch cooking.

[DannyCPAP]

Thank you very much. I am not sure what is Sleepyhead and were to get it. I have insomnia besides the diagnosed apnea. Hard to fall asleep, and I wake up because of that regardless of apnea. I am trying to isolate,distinguish and understand events to better discuss possible solutions with my doctors. It is not denial as someone replied to me earlier. It is the pure understanding that nobody else will take the time and effort to do that for me. Meditation, which helps somewhat (I am just in the initial phase of learning how to do that), came actually as an advice from one doctor when I presented my analysis. I therefore suggest to anyone to keep open mind and not stopping to look for ways to improve your life.

[greatunclebill]

I am not sure what is Sleepyhead and were to get it.

http://sourceforge.net/projects/sleepyhead/

sleepyhead is software that interprets your data card data so you can see exactly what happened during the night breath by breath if you want.

[archangle]

First, please fill in your equipment on your profile. Look at the link in my signature below.

Get a copy of the summary data the doctor got. What are the AHI numbers and other info?

Get a copy of the full report from the lab. If they resist giving it to you, tell them it's a HIPAA requirement.

However, you've probably got sleep apnea. Unless the sleep techs are idiots, the test is usually conclusive. There may be some judgment in how bad the numbers are and what the right pressure is, but the apnea diagnosis is usually pretty clear cut.

You seem to be assuming that the low AHI reported by your CPAP machine means you don't need it. That is wrong.

The CPAP reports your AHI while being treated. Many of us have life threatening AHI without CPAP, but get numbers around 1 reported by the CPAP.

That's sort of the whole point of CPAP. Your apneas go away, and your AHI is low. My AHI was 0 last night and is usually under 1. I get really, really sick without CPAP, or even if I turn my pressure down to 8.

It's one of those unfair tricks of nature and physics. You can't use CPAP with a pressure under 4, so you can't tell whether you would have apnea at a pressure of 0.

1) Don't worry about central vs. obstructive if your AHI is low. Centrals may be more difficult to treat, but probably no more harmful than obstructive. The machine may not always distinguish them correctly, but it will almost always report an apnea of some type when they occur.

2) CPAP may help centrals, or it may make them worse. Once again, concentrate on low AHI. Only worry about centrals if you can't keep AHI down.

3) Your AHI without CPAP is probably a lot higher than 3.5.

4) Yes, events while awake are irrelevant. Unfortunately, the CPAP doesn't know when you're asleep and can't do this automatically. When you have an in-lab sleep test, they use an EEG to tell if you're asleep.

You might want to turn off the ramp function.

As for the rest of the questions, you're sweating the details too much. If you're getting reasonably low AHI and using the machine all the time, don't worry about it.

5) Yes, leaks can affect AHI numbers up or down. They can also cause your therapy to be less effective. If you have bad enough leaks for a large part of the night, you need to fix it.

6) Don't sweat it if your numbers are low.

7) Yes, stress, etc. can affect AHI.

What is your pressure?

[Julie]

Go to the yellow lightbulb (at the top of each page) and start reading, including all links - it sounds like you have been given some misinformation and/or have misinterpreted what you have heard... very common , but in the end you need to learn what it's all about for your health and the sooner the better. Good luck!

[Pugsy]

Sorry...I got busy and forgot my promise to find the thread I mentioned.
Here it is viewtopic.php?f=1&t=78891&p=717463#p717463
Check out my signature for information on SleepyHead. Links for the glossary and user guide for installing and use as well as download link.

If you happen to be using Windows 7 or Vista..a hint to avoid a little headache with the updates.
When you download the setup files instead of double clicking on them to begin the install process, right click the mouse and choose "run as administrator" and let the install happen. This eliminates a problem with the updates failing because the software got installed without administrator rights. This is separate from user account administrator rights. Not a huge problem as the program can be opened with administrator rights but might as well avoid that chore because people tend to forget and a month from now might wonder why an update will fail.

[kteague]

Hi. Is your doc following up with getting the rest of the report from your sleep doctor? If not, I would still request it as it may have some information that would clear up some questions about the significance of your centrals in the study.

[-tim]

3) regardless of the type of events, if the AHI is low enough (say 3.5 on average), is there any need to use a CPAP machine?

An AHI of 3.5 on the machine shows that its doing its job but you don't know what the AHI will be if you don't use the machine without some other equipment. You could have an AHI of 40 without it and 3 with it which is typical of most people here.

[ChicagoGranny]

I have insomnia besides the diagnosed apnea. Hard to fall asleep, and I wake up because of that regardless of apnea. Meditation, which helps somewhat (I am just in the initial phase of learning how to do that),

You talk about meditation but you don't mention sleep hygiene. Do you know what good sleep hygiene is? Do you practice good sleep hygiene daily?

Meditation cannot overcome poor sleep hygiene.

BTW, you have to stop all caffeine - this is one part of good sleep hygiene. Some people will tell you they only have one cup of coffee in the morning and others will tell you they have none after lunch. If you have insomnia you have to stop all caffeine.

[idamtnboy]

First, please fill in your equipment on your profile. Look at the link in my signature below.

Hey arch, I notice you list Encore Viewer as your s/w, and you machine as the S9. Those two don't go together, right? Are you using SH or ResScan, or both? Or am I misremembering some discussion about what Encore actually can read?

[Pugsy]

Hey arch, I notice you list Encore Viewer as your s/w, and you machine as the S9

Arch as gone over to the "other' side. He found a little S9 Autoset he couldn't pass up
He told me he will report on it once he get is thoughts all together.

[archangle]

First, please fill in your equipment on your profile. Look at the link in my signature below.

Hey arch, I notice you list Encore Viewer as your s/w, and you machine as the S9. Those two don't go together, right? Are you using SH or ResScan, or both? Or am I misremembering some discussion about what Encore actually can read?

I also have a PRS1 machine. I've had an S9 for a few weeks now. Encore doesn't work with the S9 as far as I know.

My Encore Viewer gets used very infrequently these days, even before I switched to the S9. SleepyHead is so much more useful to me. I list it in the "other comments." I should probably remove Encore from my equipment list, since I almost never use it.

Thanks.