Tec5 wrote: ↑Sat Nov 12, 2022 5:52 pm
To Rubicon:
1. What is AI ?
Arousal index = (number of arousals)/(hours of sleep). In the context of what's being discussed by Thumper1947 in
his post upstream we can assume the arousals being talked about are spontaneous arousals rather than ones associated with sleep disordered breathing (including snoring) and periodic limb movements.
Tec5 wrote: ↑Sat Nov 12, 2022 5:52 pm
2. What “ad” are you talking about?
The second link in
Thumper1947's post upstream goes to the website for a dentist advertising his services for maxillofacial procedures, including those advertised as "the ideal treatment for snoring and obstructive sleep apnea" among other things.
Tec5 wrote: ↑Sat Nov 12, 2022 5:52 pm
3. What does this have to do with equipping CPaPs with an oximeter sensor?
To the best of my knowledge, Rubicon hasn't written anything (pro or con) about whether CPAPs should be equipped with an oximeter sensor somehow built into them. His posts are solely aimed at legitimately questioning the claim by Thumper1947 that a spontaneous arousal index of 27 may be considered normal in folks over 60.
I will add: The whole idea of trying to use oximeter data to "tease out" whether a specific "arousal" in CPAP data is a spontaneous arousal or a respiratory related arousal is a bit ridiculous: While we may
infer that an arousal has likely occurred based on what's going on with the respiratory rate and flow rate, we cannot actually
prove an arousal has occurred because a CPAP has no EEG data. And while some breathing patterns are likely to scream out "spontaneous arousal" to people who look at flow rate data for a living (i.e. PSG techs), CPAPs have never been designed to flag spontaneous arousals. Moreover, the way CPAPs attempt to score RERAs is, itself, controversial specifically because the machine's programming is inferring both that arousal likely happened and that there was increasing respiratory effort before that inferred arousal occurred.
CPAPs are designed to flag breathing patterns in the flow rate data that are associated with known sleep disordered breathing problems. Since both apneas and hypopneas are associated with significant reductions in flow rate, CPAP machines are programmed to identify the places where the flow rate has dropped by a substantial amount. This is pretty easy for a CPAP machine to do since the flow rate can easily be measured.
Getting back on topic: Resmed and PR use different criteria for scoring hypopneas, and neither company's definition of when a hypopnea is scored is an exact duplicate of the flow rate part of the AASM definitions. (See notes at end of post.) It's also worth noting that neither Resmed nor PR claim that the data recorded by their machines is identical to, or close to identical to, what would be scored on an in-lab PSG. Rather, they say the CPAP data should be used primarily for trending information and the AHI numbers are
estimates of what the true numbers would be.
The OP in this thread posed the idea that CPAPs should have an integrated oximeter of some sort and that they should use the oximeter data along with the flow rate data to score hypopneas, presumably to eliminate the hypopneas that can get scored during periods when you are awake or when you are dozing lightly and the missing EEG data would show that you are not fully asleep. I believe the OP's idea is that if there is a drop in flow rate while you are awake, it won't have an associated O2 desat, but if you are asleep and you have a "real" hypopnea, there will be an associated O2 desat. Hence integrating an oximeter into the CPAP machine ought to weed out "false positive" events from the number of events used to calculate the AHI.
My counter position has been---and continues to be---that using oximeter data to decide which hypopneas are "real" and which are "false positives" is misleading: A real hypopnea scored under AASM H3a does not require an O2 desat in order to be scored. Hence only including hypopnea-type events in a CPAP's calculation of an AHI only if an integrated oximeter shows there is a corresponding O2 desat is guaranteed to miss every single "hypopnea with arousal"---i.e a hypopnea scored under H3a that has an arousal but no O2 desat.
----------------
Notes: Criteria for scoring hypopneas
Resmed.
Glossary of Sleep Apnea Terms:
Hypopnea is a partial blockage of the airway (shallow breathing). During a hypopnea, breathing is reduced by
50% for 10 seconds or longer.
Philips Respirionics.
Interpretation guide for Encore software compliance reports:
Hypopnea(H): defined by a
40% reduction in airflow for at least 10 seconds.
AASM.
AASM clarifies hypopnea scoring criteria:
- Recommended (H3a)
1A. Score a respiratory event as a hypopnea if ALL of the following criteria are met:
- 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).
- The duration of the ≥30% drop in signal excursion is ≥10 seconds.
- There is a ≥3% oxygen desaturation from pre-event baseline and/or the event is associated with an arousal.
OR
- Acceptable (H4a)
1B. Score a respiratory event as a hypopnea if ALL of the following criteria are met:
- 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).
- The duration of the ≥30% drop in signal excursion is ≥10 seconds.
- There is a ≥ 4% oxygen desaturation from pre-event baseline.
Please note that the criterion involving arousals is included in 1A and excluded from 1B.
