How can Sleep Lab determine pressure when I hardly slept?

Guest · Post by **Guest** » Mon May 14, 2007 11:24 pm

Wulfman wrote:
Anonymous wrote:
Goofproof wrote:The sleep test would confirm whether you slept and how long in each stage, but the patients seldom get a copy of the study so they can say whatever they want. They are the judge, jailer and jury, we are the prisoners. Jim

If we let them do it.
So you think people regularly falsify medical documents to say someone slept when they didnt?

They don't necessarily have to "falsify" the documents, but they can (and DO) prescribe whatever pressure they damn well feel like. My titration stopped at 16, but my sleep doctor wrote 18 cm. on my prescription.

Splain THAT one to me......

Den

_________________

Easy, they can go within 1-2 cm if you're still having breakthrough snoring or some hypopneas.

trogdor · Post by **trogdor** » Mon May 14, 2007 11:29 pm

Ric wrote:
Skodobah wrote:How can Sleep Lab determine pressure when I hardly slept?
Statistically speaking, THEY CAN'T

Looking over my data for the past 16 months (wooohooooh!) and looking at the 90% pressure curve, (same one they use for the titration) I can see that, depending on which night I might have had a sleep study, my oh-so-sacred "titration pressure" would have been anywhere between 7 and 15, pretty much at random. Whether or not you slept, it is still a...

DART GAME !
What's your pressure? Throw a dart. Your pressure doesn't seem to be working? Throw another dart!
That's why I believe EVERYBODY deserves a multi-night study with a data-recording auto-titrating xPAP device. Even if you learn that your pressure is a nearly constant night after night after night (that is the working assumption of a one-night titration study), you deserve an objective answer to the question. It can't be done in a one-night sleep study.

Better yet, I believe the time has come that an APAP should be the standard issue for EVERYBODY. In the (unlikely) event that a single pressure will suffice, the APAP can function perfectly as a CPAP.

BTW, my sleep study titration pressure was an amazingly low 7, which I have subsequently recorded on only a scant few nights in the past 16 months. If I were given a straight CPAP set on 7 I would have thrown the thing out the window long ago and never gone back. Which in fact is what about half the people who start CPAP therapy actually do. Which is why the long term compliance rate remains a dismal <50%. In the past several months my "90% pressure" has stayed mostly in the range of 8-13, most commonly about 11. In the summer months my most common titration value (statistically the "mode") is around 9, for reasons I can't explain exactly. Point being, pressures drift all over the map, from night to night, seasonally, and apparently at random. The idea of a constant "90% titration pressure" that is stable (like your height, temperature, visual acuity, gender, etc.) is absurd. The titration pressure has got to be one of the mostly widely varying parameters one can imagine. That, based on looking at many multi-night data recordings from people who use APAP and record their data. For the record, I have seen one recording, a three-week interval (a friend of mine) whose 90% pressure was a steady 11cm except for 2 nights. (AMAZING!) That is exceptional, they do exist.

Skodobah wrote:I think I need to get another sleep study.

Beg, borrow, steal, rent, (whatever) an APAP, do your own sleep study titration. That's what many of the sleep labs use anyway. And who can sleep "normally" in a sleep lab anywaaaaaaaayz?

-Ric

that APAP does not track many necessary variables. AHI doesnt mean anything if you still have an arousal index of 12. It's a ridiculous assumption that sleep labs are just ''throwing darts''.

Ric · Post by **Ric** » Tue May 15, 2007 1:24 am

trogdor wrote: that APAP does not track many necessary variables. AHI doesnt mean anything if you still have an arousal index of 12. It's a ridiculous assumption that sleep labs are just ''throwing darts''.

Please note that I did not state that owning an APAP is the equivalent of a complete sleep study, only the pressure titration part. I also didn't comment on AHI, arousal index, or whatever else you have in mind. And I have never stated that a sleep study is useless. Quite the opposite, a sleep study is VERY important, it is looking for a lot of other conditions than mere OSA; centrals for example, and other medical conditions not even related to breathing problems, the list is long. Julie's original question related to the titration pressure only.

However, wearing my statistician's hat, I stand by my assertion that a few hours in a sleep lab yields a very poor estimate of an individual's "titration pressure", which is supposedly some physiological "constant", which turns out to be more of a variable than a constant. (Remember "Osborn's law": "Variables don't, constants aren't" )

My own example (which you quoted above) remains an excellent case in point; Not only was the titration WAAAAAAAAAY off as a statistical estimate of my "true" titration pressure (whatever that means), it also would have lead to a DISASTROUS clinical experience, would not have treated the OSA, would have been very expensive and a complete waste of time and money had I taken their advice and bought the el-cheapo straight CPAP they were pushing, set on a steady pressure of 7 cm. And yes, after a few months of no results, they would cheerfully re-schedule me for another titration. And another. (assuming I had not already sold the machine on eBay, or dismantled it for parts...). I actually don't regret tuning in to cpaptalk and getting advice from the real people that actually USE this equipment, and getting an APAP from day one. Then learning how to operate it and interpret the results. (thanks people !!!)

One thing a one-night titration cannot POSSIBLY measure is an estimate of variability (mean, standard deviation, distribution, etc.). Reason being, there is only ONE (1) data point. Ponder the "distribution" of a single data point. The real problem is that many people will have a wildly different "titration pressure" from night to night. And a one night sleep study will not pick that up. Simply can't.

The DART GAME paradigm remains, undisturbed.

-Ric

Guest · Post by **Guest** » Tue May 15, 2007 1:39 am

so nobody has ever used any empirical data to show a single night titration satisfactory for apnea patients within 2 standard deviations of the norm?

I'd be interested in a graph of people on here APAP v. titration pressures... I bet less people are outliers than you suspect.

Additionally, how would we know the APAP isnt overtitrating for compensatory pauses following arousals or if the APAP stays calibrated properly?

We recalibrate our CPAP equipment nightly using an analog manometer...

Food for thought.

Guest · Post by **Guest** » Tue May 15, 2007 1:49 am

wait... arent you using one data point for your statistical analysis? Who says you're not the outlier... the one whose pressure wasnt correct? Who said the machine is even reading correctly. We cant reject the null here, not enough data.

StillAnotherGuest · Post by **StillAnotherGuest** » Tue May 15, 2007 4:14 am

Hey Julie, if you go to get a copy of the sleep study results, make sure you grab the graphics page(s). Get the "complete" report, not just the "summary".
SAG

Ric · Post by **Ric** » Tue May 15, 2007 11:38 am

Anonymous DME/sleep tech wrote:wait... arent you using one data point for your statistical analysis?

Simple answer: NO!

Anonymous DME/sleep tech wrote:Who says you're not the outlier... the one whose pressure wasnt correct? Who said the machine is even reading correctly. We cant reject the null here, not enough data.

If a single night's titration is regarded as a single data point, then I would venture that a substantial majority of your customers have but a single data point, and some maybe (repeat customers?) perhaps "several" ???.

As I have been on APAP since about December of 2005 and have dutifully downloaded the data from my RemStar AUTO for most of those nights, I have roughly 500 "data points" for one individual, myself.

BTW, I also have a few thousand "data points" from friends whose cards I have read, some of whom are willing to share the data, which I will, but in a different thread. The message is the same, the sacred "90% titration" is all over the map from night to night, for most of these. Sorry to have to break the news. I realize that your working assumption (and your business) relies on the notion that everybody is remarkably constant (with regard to their titration pressure) until proven otherwise. I actually admire sleep labs who send their patients home with an auto-titrating data-recording XPAP device for several weeks or a month to answer that very question about variability, to get "the rest of the story" (as Paul Harvey would say ). Sadly, they are in the minority at present.

If your "null hypothesis" is that "any given individual does NOT vary significantly in the pressure requirements needed to splint the airway sufficient to maintain a continuous and uninterrupted breathing pattern necessary for sustaining life and for preventing obstructive events that could lead to an untoward reduction in the partial pressure of O2", (or however you'd like to say it....), then I would have to reject the null hypothesis, with high confidence.

Cordially,

-Ric

ufo13 · Post by **ufo13** » Tue May 15, 2007 1:50 pm

Hey GUEST, don't know who you are or what credentials you have, but it seems to me you are short on knowledge or have the "blinkers on" and are looking straight ahead and can see nothing around you! On the other hand I know who Ric is and he makes perfect sense to me! I suggest you read his posts again (take OFF the blinkers) and maybe you can learn something valuable! Ric is just telling it like it is! In the 13 years I have been on cpap, dealing with sleep labs, doctors, DME's, I have found his observations to be correct! I for one will take his information to the bank, as I said he makes perfect sense to me!

Steve,
ufo13

gasp · Post by **gasp** » Tue May 15, 2007 8:11 pm

Anonymous wrote:
gasp wrote:- what do I need to purchase to use the machine during a power outage? This year alone We were without power for over 10 days.

LyleHaze: Your machine will run off a car battery, either by getting (or making) a cigarette lighter cord or by clipping straight to the battery. . . .

Goofproof: A good sized Deep cycle battery will drive the XPAP 3 or more nights, as far as the HH, using is as passover only works fine, Den and I do this all the time, as cooler works better for us. Jim
Thanks to both of you. We have some spare and not used up all the way UPS batteries that could work then.

I sense an adventure coming at some point. No wonder we have a forum - it's kind of like being a survivor.

Goofproof · Post by **Goofproof** » Tue May 15, 2007 8:51 pm

gasp wrote:
Anonymous wrote:
gasp wrote:- what do I need to purchase to use the machine during a power outage? This year alone We were without power for over 10 days.

LyleHaze: Your machine will run off a car battery, either by getting (or making) a cigarette lighter cord or by clipping straight to the battery. . . .

Goofproof: A good sized Deep cycle battery will drive the XPAP 3 or more nights, as far as the HH, using is as passover only works fine, Den and I do this all the time, as cooler works better for us. Jim
Thanks to both of you. We have some spare and not used up all the way UPS batteries that could work then.

I sense an adventure coming at some point. No wonder we have a forum - it's kind of like being a survivor.

UPS batteries have their place, but most don't have the raw power for the long haul. A one or two hour outage ok, but for long term outages 45 or more AMPs are needed 65 is real nice, as long as you don't have to carry it. Jim

Guest · Post by **Guest** » Tue May 15, 2007 9:15 pm

[quote="ufo13"]Hey GUEST, don't know who you are or what credentials you have, but it seems to me you are short on knowledge or have the "blinkers on" and are looking straight ahead and can see nothing around you! On the other hand I know who Ric is and he makes perfect sense to me! I suggest you read his posts again (take OFF the blinkers) and maybe you can learn something valuable! Ric is just telling it like it is! In the 13 years I have been on cpap, dealing with sleep labs, doctors, DME's, I have found his observations to be correct! I for one will take his information to the bank, as I said he makes perfect sense to me!

Steve,
ufo13

Hey Steve,

You're a XPAP user and telling me I have blinders on? I have a hard time believing the medical community has been wrong for 25 years on single night titrations. While I do understand how DME companies drop the ball on occasion, I dont agree with the analysis of modern medicine a lot of people on here seem to have made. I have a BS in Biology and am an RPSGT, and a future PA. I post in the chat room under ''superjet'' or some variation of the word ''jet''. Anyone in the chat regularly will tell you I am informed and have an understanding of sleep and am more than helpful for anyone with questions related to sleep.

While you may not appreciate my viewpoint, I can tell you I dont appreciate the viewpoints of borderline tinfoil hat wearing patients who think the medical community can do nothing right. The slanted views (not saying ric) of most here on APAPs and titration studies attempt to ignore a lot of variables which contribute to health concerns for patients and providers alike.

cpapernewbie · Post by **cpapernewbie** » Tue May 15, 2007 9:57 pm

Guest RT

Just to give a simple example and it is a true story

after using CPAP I measure my BP almost daily

on a single day single measure: 150/110 -
next day 3 measures" 11070, 110/76. 120/80

If the treatment is based on that single day, I have to get HBP treatment

If I visited my GP on day 2, I will get praises: " See, CPAP has reduced your BP"

Guest · Post by **Guest** » Tue May 15, 2007 11:08 pm

LMAO, that's a pretty weak example.

lmmo · Post by **lmmo** » Wed May 16, 2007 1:15 am

I am trying to think that guest BS, RPSGT is getting at the fact that during a titration , we would not increase cpap pressures for "variables" such as apneas occurring post movement or post arousals that the apap may titrate mistakenly. If the pt has frequent leg movements, this could also cause post movement arousal apneas/pauses. If the pt has a leak (even a small one), the apap may increase the pressure misunderstanding the vibration as a snore. I hope this brings some light into the topic.

akcpapguy · Post by **akcpapguy** » Wed May 16, 2007 1:15 am

Ok, i'm not going to get into the stats argument, cause that's not my bag.

However I will say that Guest has brought up so valid points about APAP.

1) It doesn't account for compensatory pauses after arousals.

2) It doesn't not measure TRUE hypopneas. I did a sleep study on myself using an APAP as the titration and one of my techs did a false titration on a remote machine based on their opinion. Myself, the tech and a Sleep Doc all scored my study individually without knowing how the others had scored. We all suggested a pressure based on the study and and the false titration that was documented by EPOC by the tech. Then we downloaded the APAP data and did a time point overlay on the sleep study data, sure enough the APAP had overtitrated by 3 cmh2o at the 90%. Why, it's simple, I was having spontaneous arousals which caused compensatory pauses afterwards and the APAP recorded these as either hypopneas or apneas, and in turn increased the pressure to get rid of them. When the Neuro Doc came in he said I probably just had some loose wires in my head because I was a Ranger! I can live with that assesment.

Anyway, I can see the draw of the APAP for those who like to try manage their own treatment, however I strongly caution those of you who are trying to attain the 0 AHI. You may be over titrating yourself. However I digress, that is a topic for a different thread.

And if your Sleep Lab uses an APAP for your titration study, I would seek another Sleep Lab.

Darin

How can Sleep Lab determine pressure when I hardly slept?

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