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[Treatment] Is AHI misleading?
#21
RE: Is AHI misleading?
(05-16-2012, 12:08 PM)CHanlon Wrote: I point that out just to say that at least AHI is consistent. :-p

And the target range in both countries is still identical, merely the choice of how to describe the result is different. Like English or metric measurements. One would hope that people using any testing measure would be aware of the specific parameters used in that test.
Breathing keeps you alive. And PAP helps keep you breathing!
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#22
RE: Is AHI misleading?
(05-16-2012, 12:48 PM)JumpStart Wrote:
(05-16-2012, 12:08 PM)CHanlon Wrote: I point that out just to say that at least AHI is consistent. :-p

And the target range in both countries is still identical, merely the choice of how to describe the result is different. Like English or metric measurements. One would hope that people using any testing measure would be aware of the specific parameters used in that test.

Actually, one of the people I was thinking of was my mother in law, a retired nurse in the US. She actually had no idea that her number up here (Canada) are "OMG!" worthy. She had to start keeping an eye on hers after a stroke, first time she mentioned "I'm doing good, my glucose is steady at about 90..." I nearly fell over. :-p

"90??? My god, how high was it? are they putting you on insulin???"

Heh, she didn't know what I was talking about. TGIG... "Thank God I Google..." :-)


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#23
RE: Is AHI misleading?
In my situation, if I have less than 7 hours of sleep I get miserable at some point the next day. Other factors that contribute to lack of good sleep are stress and poor diet. I don't know how dehydration plays a role, but there's no question that hydrating yourself is healthy regardless.

My AHI info perplexes me because mine is less than 5 but if it's that high I'm extremely miserable the next day. So it all depends on the individual.
Not your ordinary Moe Schmoe
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#24
RE: Is AHI misleading?
I can have a night well under 5.0 AHI, but if I've had a single rough stretch of a half-dozen events in a half hour, as I frequently do, I can still feel crummy in the morning. Averages are misleading in the sense that life can be really awful in a town of 100 people with an average income of $100,000 -- if one of those people makes $10 million a year the rest are going to be starving.
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#25
RE: Is AHI misleading?
(05-14-2012, 02:57 PM)zonk Wrote:
(05-14-2012, 01:21 PM)SamWong2012 Wrote: Is AHI misleading? Is my VPAP therapy really working?
Prof Colin Sullivan the inventor of CPAP doesn't regard AHI useful (...)
"It really is a no-brainer," Dr. Sullivan remarked, pointing out that CPAP administration is especially easy with the newer devices that automatically set the appropriate amount of positive pressure.

As I have to live with a xPAP machine, how do I find a machine on the market today which AHI score has the lowest margin of error and how do I self-titrate such machine while taking into account that its AHI score is probably not accurate enough? Is a recording oximeter a tool better than AHI to evaluate the efficacy of xPAP therapy?

Looking for an answer I had a sleep study done using my own auto BiPAP in a sleep lab. Results:

first sleep study, BiPAP mode = fixed pressure 15/11
my BiPAP: AHI=1.9,
Lab:.........AHI=16.7 (AHI in REM=29.2, lowest oxygen = 71%)

second sleep study 2 weeks later, (auto BiPAP mode = "automatically calculate the appropriate amount of pressure" in the range IPAP=12-16, EPAP=IPAP-2)
my BiPAP: AHI=3.8
Lab:.........AHI=20.1 (AHI in REM = 16.5, lowest oxygen = 76%)
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#26
RE: Is AHI misleading?
I've been on this journey for 45 days, so I am a newbie... But I have noticed that a bad night sleep / high AHI doesn't hit me until 24 hours later... If Monday night is bad, I feel like crap on Wednesday.

what I'm having trouble figuring out is why my AHI goes up every night around 2AM for about 30-45 minutes... sleepshead shows obstructives are the cause, no CA, no hypopneas, etc... My leaks are well below 24 all night.

but every night around 2AM, snores increase, tidal volume increase... 30-45 minutes later, everything returns to normal....





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#27
RE: Is AHI misleading?
(11-03-2012, 02:48 AM)lv3101 Wrote: As I have to live with a xPAP machine, how do I find a machine on the market today which AHI score has the lowest margin of error and how do I self-titrate such machine while taking into account that its AHI score is probably not accurate enough? Is a recording oximeter a tool better than AHI to evaluate the efficacy of xPAP therapy?

What "BiPAP Auto" machine do you have? Does it say "Philips Respironics" on it? Does it say "M series?"

There's not necessarily any one "correct" AHI number. Even with humans reading an in lab PSG test, you might get different scores if two different people interpret the results. AHI is an tool to help you evaluate what's going on, not a precise measurement of the effect on your body.

A recording pulseox is a useful tool. If it shows you have oxygen desaturation, you probably do have it. Unfortunately, you can have severe apnea and not desaturate. Some people will partially wake up and breathe before their O2 levels drop in your fingers.

If you get a PRS1 BiPAP machine or an S9 VPAP, you can look at your airflow waveform and get much more detail about the individual events and determine more about how "real" and severe the events are.
Get the free OSCAR CPAP software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
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#28
RE: Is AHI misleading?
(11-03-2012, 02:48 AM)lv3101 Wrote: As I have to live with a xPAP machine, how do I find a machine on the market today which AHI score has the lowest margin of error and how do I self-titrate such machine while taking into account that its AHI score is probably not accurate enough? Is a recording oximeter a tool better than AHI to evaluate the efficacy of xPAP therapy?

Those are some awesome questions. First of all, all the machines seem to be accurate. With today's technology this measurement is pretty simple.

As to whether the measurements are meaningful, well, that's another question. They are what they are, and care must be taken in interpreting them.

Yes, an oximeter in combination with a good PAP machine can be helpful. I don't use one because my events are relatively short and in my sleep study my oxygen level didn't drop much during my events.

Quote:Looking for an answer I had a sleep study done using my own auto BiPAP in a sleep lab. Results:

first sleep study, BiPAP mode = fixed pressure 15/11
my BiPAP: AHI=1.9,
Lab:.........AHI=16.7 (AHI in REM=29.2, lowest oxygen = 71%)

second sleep study 2 weeks later, (auto BiPAP mode = "automatically calculate the appropriate amount of pressure" in the range IPAP=12-16, EPAP=IPAP-2)
my BiPAP: AHI=3.8
Lab:.........AHI=20.1 (AHI in REM = 16.5, lowest oxygen = 76%)

These are for one night only? I can't draw a conclusion because the numbers are so close. I'd recommend gathering more data. Run the machine in either auto or fixed mode and monitor the results.

There are no pat answers to your important questions. You need to monitor and ask specific questions about possible adjustments. And don't be too quick to make changes, you need data collected over several nights to be able to draw conclusions.[/quote]
Sleepster

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#29
RE: Is AHI misleading?
What Sleepster says is important. Don't make quick changes. Make a change and monitor it for two weeks. If necessary, make another and monitor for another 2 weeks. It takes time for the body to adjust and the trends to settle down.
PaulaO

Take a deep breath and count to zen.




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#30
RE: Is AHI misleading?
@Sleepster> "all the machines seem to be accurate"
All machines have a margin of error. Based on my tests described in my fist post in this thread the margin of error of my machine (which is considered market leader) was > 500% (my machine calculated AHI=1.9 while the sleep lab calculated AHI=16.7)

@Sleepster> "These are for one night only?"
These are for 2 different overnight sleep studies 2 weeks apart.

@Sleepster> "Run the machine in either auto or fixed mode and monitor the results."
That's what I've been doing with my auto BiPAP (bought in Jan. 2012) for months. It shows average AHI < 2.

@Sleepster> "You need to monitor and ask specific questions about possible adjustments."
@PaulaO2> "Make a change and monitor it for two weeks."
My specific questions (again) are:
How can I monitor and adjust my auto BiPAP if the margin of error in the AHI numbers showed by biPAP is above 500%? My machine is showing AHI=1.9 and one could be mislead to think I'm getting an effective therapy. But a sleep lab is showing that while sleeping with my machine my AHI in REM is 29.2!


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