the truth about AHI

[TASmart]

According to AASM via their recommended scoring procedure, a desaturation is not a necessary condition for scoring a hypopnea. To wit:

Recommended
1A. Score a respiratory event as a hypopnea if ALL of the following criteria are met:
a. The peak signal excursions drop by ≥30% of pre-event baseline using nasal pressure (diagnostic study), PAP device flow (titration study), or an alternative hypopnea sensor (diagnostic study).
b. The duration of the ≥30% drop in signal excursion is ≥10 seconds.
c. There is a ≥3% oxygen desaturation from pre-event baseline and/or the event is associated with an arousal.

The RDI index does not cover all arousals, only respiratory-related arousals. RDI and RERA cannot actually be determined by the XPAP, only estimated based on flow reduction. the necessary arousals cannot be determined with a PAP, or an in-home test.

[Jay Aitchsee]

According to AASM via their recommended scoring procedure, a desaturation is not a necessary condition for scoring a hypopnea. To wit:
Recommended
1A. Score a respiratory event as a hypopnea if ALL of the following criteria are met:
a. The peak signal excursions drop by ≥30% of pre-event baseline using nasal pressure (diagnostic study), PAP device flow (titration study), or an alternative hypopnea sensor (diagnostic study).
b. The duration of the ≥30% drop in signal excursion is ≥10 seconds.
c. There is a ≥3% oxygen desaturation from pre-event baseline and/or the event is associated with an arousal.

Yes, a 3% desaturation or an arousal

Or,
Acceptable
1B. Score a respiratory event as a hypopnea if ALL of the following criteria are met:
a. The peak signal excursions drop by ≥30% of pre-event baseline using nasal pressure (diagnostic study), PAP device flow (titration study), or an alternative hypopnea sensor (diagnostic study).
b. The duration of the ≥30% drop in signal excursion is ≥10 seconds.
c. There is a ≥ 4% oxygen desaturation from pre-event baseline.

Again, https://aasm.org/aasm-clarifies-hypopne ... -criteria/

[Arlene1963]

I believe you are correct, Arlene, without looking it up, that ResMed uses 50%, at least for older machines. The AASM (American Academy of Sleep Medicine) recommends scoring a hypopnea with a 30% reduction in flow in conjunction with a corresponding oxygen desaturation of 3 or 4%. See https://aasm.org/aasm-clarifies-hypopne ... -criteria/
The information I have regarding ResMed criteria is somewhat dated. It is possible that newer machines (Airsense and Aircurve models) use different scoring criteria. ResMed implies they report in accordance with AASM guideline, but I can't verify that.

Thanks, Jay. I wasn't sure and couldn't find the info online.

Based on the info in this prospective clinical trial planned by ResMed it seems that the Airsense 10 Autoset for Her uses the 30% criterion as per AASM guidelines. So yes, newer machines might use the 30% reduction in flow.

https://clinicaltrials.gov/ct2/show/NCT03043703

Interesting study. Wish I could participate.

[Jay Aitchsee]

Yes, Arlene, ResMed says (in reference to their Airview system) that they use AASM criteria for scoring: https://airview.resmed.com/resources/we ... g_AMER.pdf and I'm guessing the newer machines use 30%.

I don't care to participate in the study https://clinicaltrials.gov/ct2/show/NCT03043703, but I would like to know the outcome. Essentially, it looks as if they are testing the ability of ResMed to accurately detect RERA. If they can, it should make the OP of this thread (and others) happy Since ResMed is sponsoring the study, they must feel confident in their ability.

[Arlene1963]

YSince ResMed is sponsoring the study, they must feel confident in their ability.

Spot-on!!!

[Jay Aitchsee]

So, XX, RDI = Apneas + Hypopneas + RERAs per hour of sleep.
But RERAs by definition end in an arousal.
I agree that RDI is an important index. But how do we measure RERA at home? And what if we could measure it? What is the treatment for RERA? What are you suggesting, XX?

(Moved from the Einstein thread)

[Not Fade]

the point is that even if you cant measure it
RDI is the important number not AHI

LMAO. If you can't measure it, how can it be important?

What we can do in this forum is work to get our AHI low, address comorbidities and use good sleep hygiene/lifestyle. If our Epworth Sleepiness Scale score is still poor, another lab sleep study may be helpful.

I find your constant rantings about RDI to be counterproductive to the great work this forum has a history of.

You won't stop. But, karma will get you at some point.

[Guest]

just because ResMed does not care to record RERAs does not mean that other devices can not. Philips is doing that, Weinmann / Loewenstein as well - and that for a very long time.
Who actually cares about if there was a real "arousal"? If the breahting pattern looks disturbed there was something going on, which could lead to an arousal - no need to make a full EEG. Take care of the RERA detected by the machine - the rest falls in place.

UARS is however the name of a disease NOT an event or any kind of breathing disturbance - there is even a lot of "talk" about doctors / scientists around how this can be measured. (to do that "correctly" you would have to intubate the patient)

But I really don't understand the point you are trying to make. (And from the looks of it I am not alone with that)
Are just trying to say, that depending on the underlying disease the metrics do change? - that is no new info.

You make a lot of yada,yada about what "metric" should be applied next if the other ones do not reflect the subjective feeling .. to what end actually?
Are you just looking for some sort of proof or medical name to your feeling - or to what end exactly are you doing this kind of stuff?

ResMed sucks at scoring anything at all - if you want to self-diagnose yourself just with the equipment at hand get yourself a machine that is capable of scoring all the necessary events - or at the very least gives you access to unfiltered flow-data.
If you just want treatment stick with the ResMed-Device.

If you got lost until here: WHAT exactly do you want? - you have been asked a couple of times in what context your yada,yada is or should be?
Without any context this whole thread is just a waste of time and nothing more than (really bad!) noise!

[TASmart]

The Resmed airsense 10 auto does record reras as best it can by looking at the airflow. I believe that the ResMed ASV does the same based on xxyzx's complaint that he can not see why the event is flagged in some cases.

[Guest]

stays the same - ResMed is for treatment not for diagnosis! (they do suck at showing anything - it is always fine with ResMed ... no matter what or how you bad you do)

[Guest]

are you saying resmed diddles the flow data? it looks real on sleepyhead.

How do you believe the devices capture EXACTLY the respiratory flow? (HOW EXACTLY!)

But I still don't get your point about the truth of AHI. If you get diagnosed with a sleep related breathing disorder / disease AHI (or RDI if you like - but it is the same!) is the metric to use. The magnitude of the breathing issues can however be measured by the ODI (that is your SPO2).
If the AHI is "fixed" so is the ODI. (the other way around is just false!)

Just because you have a SRBD does not mean you are otherwise healthy - does not make the AHI less important.
If you have UARS your AHI / RDI (or ODI for that matter) is of no importance as that is a total different disease. You have an arousal long before an event even gets scored.

Sleep deprivation results in death! Really - believe it or not. There is a reason why it is not allowed by the geneva convention.

[Guest]

i would expect resmed uses analog sensors to monitor the flow and samples them to record digital samples that sleepyhead plots
air flow is so slow that a modest sampling rate ensures perfect recreation of the flow according to nyquists theorem

Actually I expected as much.

Let me rephrase the question:
If your masks vents about 40 liters per minute and you can have some changing leaks on top of that and your normal respiratory flow is about 7.5 liters per minute.

How EXACTLY would the machine "measure" your respiratory flow (to YOUR believe)? (explain it to me like I am 4 years old)

[CapnLoki]

...
AHI can be 'fixed' but not mean that spo2 desats are fixed

AHi is only important wrt OA and its treatment but is still a crude measure of effectiveness

i would expect resmed uses analog sensors to monitor the flow and samples them to record digital samples that sleepyhead plots
air flow is so slow that a modest sampling rate ensures perfect recreation of the flow according to nyquists theorem

You seem to be saying that RERAs cause desaturation, but that runs counter to Sleep Medicine Pearls, Berry & Wagner 2014
https://www.amazon.com/Sleep-Medicine-P ... 1455770515
which points out the since RERA are like Hypopneas that don't meet the full definition, the primary difference is that RERAs don't cause desats.
"If the AASM acceptable definition of hypopnea (drop in flow >4% desaturation) is used, most RERA event do not meet the criteria to be scored as hypopnea because of the absence of an associated oxygen desaturation or required severity." It goes on to say the RERA are still significant because they cause daytime fatigue.

This does not rule out the possibility that a particular RERA does cause a desat but is not a hypopnea for another reason, but does state clearly that this is not common,

This seems to directly contradict your claim that RERA's cause desats and lowering AHI does not prevent this.

[ChicagoGranny]

(explain it to me like I am 4 years old)

Good luck with that. His habit is to explain things like he is four years old.

[Guest]

are you saying resmed diddles the flow data? it looks real on sleepyhead.

How EXACTLY would the machine "measure" your respiratory flow (to YOUR believe)? (explain it to me like I am 4 years old)

you tell me how it does it

Is this just some troll thread for you or are you actually interested in something?

What is your mumbling now about RERAs? YOU said you can have desats if the AHI is 0 - what else is there than RERAs? What you said effectively means, that to your believe RERAs are causing desaturations.