Does a sleep study HAVE to show AHI greater than 5 to warrant cpap use?

[Morbius]

We should also consider the "almost apneas" that last less than 10 seconds but aren't recorded

Why should we do that?

Especially if it doesn't result in a desaturation or an arousal?

[Pugsy]

Well I'll toss in a couple things!

Which was just how critical is that medical profession line in the sand of 5.0 AHI????

IMO the "medical profession" as a whole, NEVER drew lines in the sand re: treatment for anything. Certainly, a good clinician wouldn't allow himself to be boxed in by insurance-driven criteria.

AHI has ALWAYS been under critical review. Even more so recently:

https://onlinelibrary.wiley.com/doi/ful ... /jsr.13066

That said, I'd really like to see some of these cases with <5.0 AHI with complete turnarounds in their lives. Were they HSTs? Self-diagnose and treat? "I feel great since starting CPAP, lowering my AHI from 3.1 to 2.5 and oh BTW stopped downing a bottle of Stoli every day!" Placebo?

I guess using the term "medical profession" probably wasn't the best but I can't think of any other term for the system that relies on the AHI marker for classification. I am also including the insurance system here which relies on a line in the sand before they will pay for anything. Doctors would be happy to treat whatever/however but insurance doesn't always want to pay for said treatment so that's where the line in the sand grows in importance.

My doc would be happy to prescribe a hot tub for my back problems but my insurance still won't pay for that hot tub I might want. There's no doubt that a hot tub would help my general unwanted symptoms but not everyone has the funds to say screw the insurance I will just buy one on my own. Same thing applies to cpap therapy.

I did read that article you linked to and it does affirm what a lot of us have always said....we need to look at the big picture more and rely less on one set of numbers. Clinical correlation is still important.
This statement particularly hit home with me.

In summary, to have OSA is not necessarily the same as to suffer from OSA.

And I would also like to see some studies where someone has a nice low "normal" sub 5.0 diagnostic AHI but substantial clinical symptoms get resolved by going on cpap.
Subjective feelings are always difficult to measure though. I get that reality every time someone wants me to rate my pain levels from 1 to 10. It's not always so easy.
Then there's the "bad sleep from other factors" thing muddying up the waters and people want to put all their eggs in the OSA basket and expect cpap to fix them when cpap can't fix them.
You know the person who takes a medication that messes with sleep and makes them feel like crap during the day who starts cpap and doesn't see any improvement yet it's cpap failure because cpap didn't alleviate the problem when they expected cpap to fix a problem that it was never designed to fix but it's cpaps fault.

I guess all I can do is work with what we have currently though and perhaps at some point in the future we will have a different standard to work with when trying to help people sort through all these varying issues.
I am still of the opinion that cpap is worth at least trying for those that "suffer from OSA symptoms" and we can't blame those symptoms on anything else. Might get lucky and have success and even though a remote chance...a chance nonetheless. Expensive experiment though and with insurance not helping out due to their line in the sand it's an experiment that not everyone will be able to do.

Nothing is ever simple no matter how much we might want it to be.

[Morbius]

And I would also like to see some studies where someone has a nice low "normal" sub 5.0 diagnostic AHI but substantial clinical symptoms get resolved by going on cpap.

Krakow did (and does) a lot of stuff on that but frankly he lost any credibility with me after misidentifying "expiratory intolerance" as cardiac oscillations, then later printed some PSG examples in a journal where respiratory effort channels were upside down. Maybe he was getting bad info from the techs, IDK.

Anyway, he has some interesting thoughts:

https://sleepreviewmag.com/sleep-disord ... a-and-sdb/

I would offer that some of the people who are in this group we are discussing also have basic sleep hygiene issues, and perhaps just bringing the global issue of the importance of sleep to their attention starts them on a path to improve sleep quality. They see a minimal reduction in AHI and attribute their improvement to it, when in fact there may be many factors in play.

[Respirator99]

We should also consider the "almost apneas" that last less than 10 seconds but aren't recorded

Why should we do that?

Especially if it doesn't result in a desaturation or an arousal?

I don't know anything that says a 9.5 second "almost apnea" doesn't cause arousal but a 10 second one does. The 10 second thing is just another arbitrary line in the sand. But if you're getting a whole lot of almost apneas you're still going to feel bad, even if your AHI is very low. Another case where an AHI under 5 is not giving you the whole story. You're probably aware that Oscar has an option to flag and record user-defined breathing disturbances. It was quite an eye-opener for me to see how any "almost apneas" I was getting. Adjusted pressures to minimise them and felt much better.

[Morbius]

We should also consider the "almost apneas" that last less than 10 seconds but aren't recorded

Why should we do that?

Especially if it doesn't result in a desaturation or an arousal?

I don't know anything that says a 9.5 second "almost apnea" doesn't cause arousal but a 10 second one does.

That's not what I said.

If an "event" is <10 seconds and there is no arousal or desaturation it is not an event at all. It's just a low respiratory rate.

[Morbius]

It was quite an eye-opener for me to see how any "almost apneas" I was getting. Adjusted pressures to minimise them ...

Far be it for me to make any judgement calls tho. Print up some examples of these as well as total night results showing improvement to share with the group.

[Pugsy]

We should also consider the "almost apneas" that last less than 10 seconds but aren't recorded

Why should we do that?

Especially if it doesn't result in a desaturation or an arousal?

My personal opinion is that the key is arousal or not. An almost apnea isn't likely to cause a desat in most people unless they happen to have a truckload of them back to back but an almost apnea could definitely cause an arousal and thus mess with overall sleep quality in that manner which ends up messing with how we feel.
And most people are wanting to fix how they feel anyway.

I have the below flow rate graph from an individual who didn't meet diagnostic criteria (AHI wise anyway) during an in lab sleep study where he came out with AHI of 2 something I think it was but his sleep quality was totally in the toilet and thus how he felt was also in the toilet. Arousal breathing everywhere and minimal amount of actual asleep breathing.
Lots of false positives flagged by the machine and his AHI on cpap was actually worse than the diagnostic sleep study because of the false positives. He pretty much felt as bad as this looks but there was a factor I could never get him to remove from his routine that might have been a potential culprit. He was on a mood altering medication that was well known to mess with sleep (mess with sleep stages and cause insomnia) AND cause fatigue during the day and it was the fatigue that was his primary complaint. While we couldn't prove the meds were having an impact....without him going off them...he was unwilling to entertain even the possibility that his meds were compounding his problems.

He wanted cpap/bilevel and even ASV (which I think this graph was with ASV) to fix his fatigue problems. Obviously unsuccessful but just wouldn't even entertain the possibility that meds were a factor.

Goes back to what caused the arousals....airway issues or something else.

[colomom]

The line in the sand of only AHI’s <5 warranting treatment is about protecting insurance companies bottom lines, sadly the patients best interest is often sacrificed in order to protect the bottom line.

A person’s AHI alone may not always give a full and complete picture of their sleep. An example that comes to mind is when a very intelligent sleep tech was able to dramatically improve my son’s sleep by looking deeper than just his AHI. My son was doing a titration study followed by a MSLT study. He had been using CPAP religiously to treat his OSA and while it had improved his sleep he was still falling asleep constantly throughout the day so his doc decided to do another titration study and a MSLT to check for Narcolepsy. During the nighttime titration part of the study the tech observed that even after they reached a pressure that put my son’s AHI into “treated” range, my son’s O2 sats were still low and he was continuing to have tons of arousals. She suspected upper air way resistance was to blame. She continued to titration him up another 3 cm which improved mean O2 saturations by 3% and dramatically decreased the number of arousals. During previous titration studies all they had considered was the AHI, fortunately this wonderful sleep tech figured out that upper airway restriction was causing numerous arousals, it’s no wonder my son was having such difficultly staying awake during the day.

I imagine there are people out there whose AHI may not reach the magical 5 number, but whose sleep would benefit from CPAP. Considering there are no adverse health issues caused by using a pap machine, it’s to bad they aren’t allowed to trial a CPAP to see if it helps.

[Morbius]

My personal opinion is that the key is arousal or not.

my son’s O2 sats were still low and he was continuing to have tons of arousals.

Zackly! AHI unto itself is totally meaningless! Desaturations and arousals are the problem!

Indeed, when Gould et al were working on definitions for hypopnea in 1988 they chose the parameters (flow reduction of >50% for 10 seconds or more) that were most able to correlate with arousals and desats. AHI is simply the means to an end.

And sure there are patients with sub-clinical hypopnea. Otero et al in 2010 presented his findings using a 5 second rule that dramatically uncovered OSA in 2 patients (out of a study group of 40). Anecdotal, or do 5% of patients have sub-clinical hypopnea?

Anyway, if you have PSG in hand showing AHI is 8.0 but Desaturation and Arousal Indices are 25.0, then you might wanna pay attention.

[Morbius]

I have the below flow rate graph from an individual ...

ewww.

[Pugsy]

ewww.

That was one of the sort of "good" ones. I didn't grab screenshots of all of them.
That guy's in lab sleep studies also showed a lot of arousals....spontaneous arousals and not so many respiratory related arousals. Big surprise there. Huge number of spontaneous arousals. Duh...ya think.
Every time I looked at his flow rate I thought of you and your "bad sleep" comments.
Always felt like it doesn't get much badder than what that guy showed. No wonder he felt like crap.
I forget exactly which mood med he was on...might have been welbutrin or something like that and we both know that it wouldn't be impossible for it to be responsible for the crappy sleep quality as well as being a zombie during the day.
He wouldn't even consider that possibility though and finally bailed on cpap/ASV since it didn't fix his "bad sleep".

My gut was sure leaning towards medication side effects playing a significant portion to his unwanted symptoms though.

[Thumper1947]

Got this last night and I don't know if it adds anything to the conversation, but it seems related, so here it is.


Bias in Scoring Respiratory Events

Barry Krakow, MD
Feb 4

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In a recent article in the Journal of Clinical Sleep Medicine, “The differential impact of respiratory event scoring criteria on CPAP eligibility in women and men,” a bias was demonstrated suggesting limited access to CPAP prescriptions in women, particularly those in the pre, peri- and post-menopausal age range (40 to 60).

The study examined diagnostic sleep study results from 674 women using two different scoring methods. The first, known as the Medicare criteria requires a 4% desaturation to define sleep breathing events. The second, offered by the American Academy of Sleep medicine (AASM) allows for either a 3% oxygen desaturation or an EEG arousal in the brain to define sleep breathing events.

The results compared the expected number of diagnoses based on each criteria, AASM vs Medicare. In every comparison, Medicare sharply decreased the number of positive cases in women. Overall, women were twice as likely to not meet criteria for sleep apnea despite having met the criteria by the AASM. Worse, in the age group from 40 to 60, the women would be 7 times more likely not to be diagnosed with Medicare criteria even though they had met AASM criteria.

These results align with some of the previous posts in that women in the age range of 40 to 60 often suffer from UARS and mild OSA, so this study confirms the Medicare bias against women who undergo sleep testing. The most worrisome aspect of the findings is women often develop hypertension at times near to menopause, which could be linked to their OSA, but Medicare’s biased scoring rules would prevent many of these women from receiving a proper diagnosis and CPAP device.

Last, bear in mind, Medicare rules are often adopted by many other insurers, so on a practical level many women could be affected by this bias.

Thumper

[BuckarooBanzai]

2...also remember that the criteria for flagging of events could potentially lend to the impression that nothing meets the line in the sand criteria when in fact physically it could still be very important. Remembering that apnea events have to meet the 10 second duration criteria first. Think about it for a minute...what if you have 15 apnea events per hour average that only last 9 seconds???? Those won't be included in that AHI total but do you really think that just because an event only lasts 9 seconds that it has zero impact on the person's sleep quality just because of that 1 second???

This is an especially good point. G-d only knows how many events occur every night that are not even recorded as events because they fail to meet that magic 10 second line-in-the-sand.

[GrumpyHere]

There are lots of tools in the box, but many of them require too much skill or experience or time to wield.

Like what?

The current forms of PSG are too expensive, cumbersome and require scoring by sleep techs.

Ear-EEGs in development seem promising but are still a ways from the marketplace.
https://en.m.wikipedia.org/wiki/Ear-EEG

The open source sleep stage autoscoring software again seems promising but needs to be packaged for non programmers.
https://elifesciences.org/articles/70092

So the components for a home PSG that can measure Arousal Index rather than AHI are there or are in development.

[Morbius]

There are lots of tools in the box, but many of them require too much skill or experience or time to wield.

Like what?

The current forms of PSG are too expensive, cumbersome and require scoring by sleep techs.

Oh.

I thought when he said "There are lots of tools in the box", they were actually "in the box".

At any rate, if you're only looking at an arousal index you don't need a PSG, you just need a single lead EEG.

It's certainly not cumbersome.

You don't need a sleep tech either. In 45 minutes I taught a high school student how to score an entire NPSG. Whole bunch of channels. And she did an absolutely bang-up job.

Although she was pretty smart, and of course, as for me...

Cost? You can get a high grade system for less than the cost of your basic CPAP unit.