CPAP vs APAP - one sleep doc's view

[Sleepless on LI]

AHI[/quote]"H" is the hypoapnea/hr in AHI, it is a 50% blockage of the airway lasting >10 seconds WITH a 3% drop in SAO2 levels.[/quote]

Guest,

Correct me if I'm wrong, but our machines that record data can't possibly be picking up on reduction on SAO2 levels, so they aren't detecting/recording a hypopnea based on that 3% drop in those levels on the data. If they could record those levels, they would be listed amongst the other data that our software reports. No? The machine has to just be picking up on the actual severity of the event, whether it's a full cessation of breathing for X amount of time, not the SAO2 desaturation.

I'm open to correction. However, I had to borrow a pulse oximeter from my DME to see my desats. while I'm on the Remstar Auto. If my machine were able to pick up on those, it would be a beautiful thing.

[different guest]

I agree with Lori. Too bad we all can't have oximeters to use. They tell the true story.....the apap/cpap, whichever you choose, the object is to improve the desats caused by osa.

[Wulfman]

I found this reference:

Hypopnea - Definition highly variable between sleep centers; however, according to a recent consensus statement, hypopnea is a 30% or greater reduction in flow associated with a 4% drop in oxygen saturation; many centers also score a hypopnea if a decrease in flow is associated with an arousal.

Here:

http://www.emedicine.com/neuro/topic419.htm


Den

[Guest]

AHI

"H" is the hypoapnea/hr in AHI, it is a 50% blockage of the airway lasting >10 seconds WITH a 3% drop in SAO2 levels.[/quote]

Guest,

Correct me if I'm wrong, but our machines that record data can't possibly be picking up on reduction on SAO2 levels, so they aren't detecting/recording a hypopnea based on that 3% drop in those levels on the data. If they could record those levels, they would be listed amongst the other data that our software reports. No? The machine has to just be picking up on the actual severity of the event, whether it's a full cessation of breathing for X amount of time, not the SAO2 desaturation.

I'm open to correction. However, I had to borrow a pulse oximeter from my DME to see my desats. while I'm on the Remstar Auto. If my machine were able to pick up on those, it would be a beautiful thing.

[Guest]

sorry correction: circadian=cardiac rhythms

[Guest]

[quote="Wulfman"]I found this reference:

Hypopnea - Definition highly variable between sleep centers; however, according to a recent consensus statement, hypopnea is a 30% or greater reduction in flow associated with a 4% drop in oxygen saturation; many centers also score a hypopnea if a decrease in flow is associated with an arousal.

Here:

http://www.emedicine.com/neuro/topic419.htm


Den

[Guest]

Which leads to my question. Other than being a loud snorer what is wrong with have a high AHI?

Snooter, I'm not derek, but I can supply a bit of information.
The AASM defines an apnea as cessation of airflow for at least 10 seconds. Desats aren't a component of that definition.
A high AHI such as 54 is defined as severe OSA. Other than being a loud snorer, complications of OSA include, among other things, increased risk for hypertension, 4x higher rate of stroke, coronary artery disease, congestive heart failure, atrial fibrillation, myocardial infarction, diabetes, depression, sexual dysfunction and death.

There's more, but I suddenly feel the urgent need to get to bed and put on my mask...

I think your doctor is trying to brainwash you

No brainwashing. Those are simply the facts. OSA is serious stuff.

[Guest]

From a previous thread on hypopneas. Ozij summed it up well, as usual!

The hypopnea definition controversy is quite a mess. It's bad enough they can't agree if desats are a necessary component of the definition. Even worse, they show when desats are measured, they can vary (enough to not meet the criteria) depending on the particular oximeter used. Not exactly an exact science, is it.

From Choice of oximeter affects apnea-hypopnea index

The use of oximetry as a confirmatory signal for respiratory events has been accorded variable importance in the past 20 years. Opinion on how to define hypopnea varies, and only limited data on outcomes exist to justify any particular choice. The AASM task force published an article in 199913 on the definition of the obstructive sleep apnea-hypopnea syndrome and the measurement techniques used for respiratory events. They did not require desaturation in the definition of hypopnea when flow was markedly reduced, but supported using desaturation in the definition of hypopnea when the events were subtle. The AASM issued a position paper in 2001 that argued that only events with 4% desaturation should be counted as hypopnea, referencing an increased reproducibility and interscorer reliability. However, Whitney et al also showed that interscorer reliability is still reasonable when reducing the desaturation requirement to 2% (93% vs 99% agreement). Furthermore, Oeverland et al found that while all patients with events that had been counted using the requirement of 4% desaturations for respiratory events had significant disease, 36% of those with detectable and probably significant respiratory events (ie, a 50% reduction in flow or arousal) were missed by this criterion. Thus, there remains a considerable debate over what level of desaturation should define a "significant" respiratory event and whether oximetry alone should define such an event.

There's nothing cut-and-dried about measuring the human body. There is a lot of science (i.e. hard work and money) behind what is understood about OSA and its treatment and the issues are far from settled. Don't make out like that's a bad thing, I'm certainly glad they understand this stuff a lot better now when I'm being treated than that did if I'd have been diagnosed 20 years ago. Heck, at one time they actually thought carving up the inside of your mouth and throat was the only way to treat apnea.

When a medical professional says something about "hypopnea this" or "flow limitation that" or "blah, blah, blah apnea" they have some specific definition in mind for those terms. If you really want to understand the implications of what they're saying, then you have to ask and make sure that you know the specifics of their working definitions. There is absolutely no magical way of guaranteeing that everyone means the same thing when they say the syllables Hy-Pop-Ne-A. You can't really have a meaningful technical conversation about this stuff unless you're sure you've pinned down the definitions.

Brent,

Point well taken. A controversial definition is better than no definition. It begs the question, however, depending upon the criteria used at the local sleep lab: how many patients (who would benefit from CPAP therapy) end up not qualifying for a diagnosis of OSA because they don't meet the cutoff as it pertains to the questionable use of desat levels for hypopneas? In addition to the hypopnea debate, I was surprised to learn the type of oximeter used can also yield such different (potentially non-qualifying) results. I should know better, though. I want this to be an exact science and it simply isn't. Even with a universally accepted definition (e.g. apnea), the interpretation and (potentially non-qualifying) scoring of PSG results can vary substantially from tech to tech. Sometimes I lose sight of the fact that sleep science is still in its infancy.

Come to think of it, I could take my temperature with 3 different thermometers and get three different results too. But, while the precision of the instrument used and the accuracy of the human interpretation may vary (for thermometers as well as PSGs), at least the criteria for measurement is standard on a thermometer. I want that same assurance for all things OSA related! Oh well... I'll try to get over it... I also want world peace and new siding on my house. That hasn't happened yet either..

If you really want to understand the implications of what they're saying, then you have to ask and make sure that you know the specifics of their working definitions. There is absolutely no magical way of guaranteeing that everyone means the same thing when they say the syllables Hy-Pop-Ne-A.

My emphasis.

Or more humourosly, as announced by the inimitable Humpty Dumpty:

"When I use word <snip> it means just what I choose it to mean -- neither more nor less"

O.

[Wulfman]

[quote="Anonymous"][quote="Wulfman"]I found this reference:

Hypopnea - Definition highly variable between sleep centers; however, according to a recent consensus statement, hypopnea is a 30% or greater reduction in flow associated with a 4% drop in oxygen saturation; many centers also score a hypopnea if a decrease in flow is associated with an arousal.

Here:

http://www.emedicine.com/neuro/topic419.htm


Den

[bugleboy]

Hello. I'm new to this site and have a few questions. I am a long-time user of CPAPs (16 years). My level is 16 and I would like some suggestions on whether a APAP would be better for me than my CPAP. I am a professional trumpet player, so should I assume exhaling against this level is probably a little easier for me than for most? Sometimes I notice that it is a little difficult to exhale, but I still fall asleep pretty quickly. I don't wake up during the night at all. The whole night is spent in one position --- on my back.

I am asking this question on this board because I have been a little sleepy lately. No weight change or any other factor that I can think of. Sleep studies give me severe anxiety.

Any help would be greatly appreciated.

[NightHawkeye]

I am a long-time user of CPAPs (16 years). My level is 16 and I would like some suggestions on whether a APAP would be better for me than my CPAP . . . I am asking this question on this board because I have been a little sleepy lately.

Hi Bugleboy, Steve, and welcome to cpaptalk. With all your years of using CPAP, I'm sure you can probably educate many of us about things CPAP related.

There have been several threads recently where folks compared CPAP to APAP and they then decided that CPAP worked best for them. Although I'm using a BiPAP, I similarly found that fixed pressure BiPAP works better for me than auto-BiPAP does. In my case, the data indicates that the onset of my apneas occurs more quickly than the auto algorithm can respond. Ergo, fixed pressures actually limit the apneas better. Not everyone has the same response though. Many folks have variable pressure needs, so an APAP allows them to spend a good portion of the night at lower pressure and they seem to benefit from that. I'm not sure there's any way to know which works best for you without trying both though.

One thing an APAP definitely does much better than CPAP is to provide more pressure if your needs require it occasionally.

Are you monitoring your events, Steve? I mean with software, so that you can see how many apneas occur each night. That could provide valuable clues as to whether your recent tiredness is related to CPAP issues.

Regards,
Bill

[bugleboy]

Bill,

Thanks for the response. When I wrote my post it was late and I wasn't thinking thoroughly. I have been using a CPAP for twelve years, not sixteen. Duh. Anyway, it's been a long time. One thing I didn't mention is that I have been 100% compliant since the first night of using a CPAP. I have been tremendously lucky that I haven't had any major discomfort problems. I hope I can keep that track record going. That's why I joined cpaptalk.

I don't believe my current machine (Fisher and Paykel HC 201) allows me to monitor my events. I've had it several years and that is one of the reasons I want to get a new one. When I had my sleep study, the doctor told me that I needed a constant pressure of 16, and if I had any problems with exhalation, to let him know. The problem is that I can't remember that doctor's name. My regular physician has changed due to retirement (his) and the office doesn't have any paperwork on that referral. I guess this means another sleep study, but those things drive me up a wall. When I have an event (w/o the machine) it scares the friggin' bejeebers out of me. Needless to say, there are quite a few of those in a sleep study. I'm not sure why they can't start the level higher. I mean, with my years of needing the machine, it seems like they could do that. No matter how much I protested, they insisted on starting me at an 8. That's like giving a drowning man a thread to pull himself up!

I think I've ranted long enough. I have a feeling I will be talking to my doctor about a BiPAP, but I would like to have the opportunity to try an APAP.

One last thing, I am a Mac user (iMac G5). Is the software compatible with my computer?

Thanks again for your help.

Steve

[Snoozin' Bluezzz]

Bump over all the spam

[GoofyUT]

AHI

"H" is the hypoapnea/hr in AHI, it is a 50% blockage of the airway lasting >10 seconds WITH a 3% drop in SAO2 levels.

Guest,

Correct me if I'm wrong, but our machines that record data can't possibly be picking up on reduction on SAO2 levels, so they aren't detecting/recording a hypopnea based on that 3% drop in those levels on the data. If they could record those levels, they would be listed amongst the other data that our software reports. No? The machine has to just be picking up on the actual severity of the event, whether it's a full cessation of breathing for X amount of time, not the SAO2 desaturation.

I'm open to correction. However, I had to borrow a pulse oximeter from my DME to see my desats. while I'm on the Remstar Auto. If my machine were able to pick up on those, it would be a beautiful thing.

[birdiebaby]

Bill,


I don't believe my current machine (Fisher and Paykel HC 201) allows me to monitor my events. I've had it several years and that is one of the reasons I want to get a new one. When I had my sleep study, the doctor told me that I needed a constant pressure of 16, and if I had any problems with exhalation, to let him know. The problem is that I can't remember that doctor's name.
<snip>
I think I've ranted long enough. I have a feeling I will be talking to my doctor about a BiPAP, but I would like to have the opportunity to try an APAP.

Steve,

You might get the benefit of a two-week trial on an APAP machine. They are often used in place of a full PSG to titrate a patient. After two weeks, your DME or Dr can look at your results and get a good idea of the pressures you now need. Of course, you'll need to find yourself a new doctor and get a prescription for that.

If you spend most of the night in one position, your pressure needs probably don't fluctuate like those of us who are active sleepers. A CPAP may be all that you need. The APAP is nice, however, becasue we can let the machine try to determine our most effective pressure settings.

As for the software for MAC OS, I kind of doubt it. There are three major software packages (Encore for Respironics, AutoScan for ResMed, and Silver Lining for Purtian Bennet). I know for sure that Encore specifies Windows. The other two I don't know. You may want to jump on their web sites.