New sleep study results

Tec5 wrote: ↑

Thu Jun 30, 2022 6:16 pm

The discussion on "accuracy" of Resmed ApneaLink is tangential to the information that Sanjay provided, and does not serve to illustrate the information he provided.

I disagree. My point is that ApneaLink airflow channel provides an excellent signal. The only time it wouldn't work is if there's nasal occlusion. Using a chin strap (or whatever he did) changed the testing criteria from signal accuracy to treatment option.

Assuming all the other variables remained constant (body position, sleep quality, scoring technician input (or did they simply AutoScore), etc.

Sanjay1976 wrote: ↑

Tue Jun 28, 2022 2:41 pm

Someone asked what the results of the studys were:
First Study (with mouth open
OAI 1.4
Hi 11.3
CAI 0.15
O2 93

Repeat (moth closed)
OAI 0.9
Hi 2.2
CAI 0.2
O2 94

Scan the entire results of both studies in. Let's look at desaturation index (among other things).

Pugsy wrote: ↑

Wed Jun 29, 2022 10:07 pm

And the first post that got derailed with all the nastiness ...

AC chose to poke the bear with a stick, and then is taken aback when her head gets bitten off?

Regardless, I apologize for my my response.

Rubicon wrote: ↑

Fri Jul 01, 2022 3:53 am

My point is that ApneaLink airflow channel provides an excellent signal. The only time it wouldn't work is if there's nasal occlusion. Using a chin strap (or whatever he did) changed the testing criteria from signal accuracy to treatment option.

We simply do not know if "they auto scored"?

I have no dispute with you over the excellence of Apnealink signal of nasal airflow. I will accept that the nasal prongs will transmit differential pressures to a sensor that accurately deduces the airflow at the nasal passages. I acknowledge that (even without "proof").

What I am concerned about is if that nasal only airflow correctly represents the airflow through both the oral and nasal pathways and therefore correctly reports the total ventilation to the lungs.

Let me try an analogy: On a vacuum sweeper the suction created by the blower fan creates an airflow at the sweeper head. This airflow is fairly consistant from moment to moment. However there is also a hole in the sweeper hose that allows the airflow at the sweeper head to be varied by open and closing that hole. (for example if one wanted to vacuum curtains, to avoid sucking the curtain into the sweeper). The vacuum's fan provides the overall suction (analogous to the expansion of the chest cavity), and vacuum breaker (hole in the hose) allows the airflow at the sweeper head to be varied (analogous to opening an alternate air pathway - the mouth). Measurement of only one of these airpathways (IF THE ALTERNATE PATHWAY IS IN PLAY) only provides a partial picture of the total airflow.

I am NOT trying to suggest that the measurement of air flow (by ApneaLinlk or others) at the nostrils is inaccurate, what I'm suggesting is that the total airflow may be inaccurate IF an alternate air passage is in play. This may be particularly significant if that alternate air passage is opened intermittently - because IMO that would open the potential for intermittent suggestions of hypopnea.

Example - for five minutes all airflow passes across the nasal cannula, then for the next three breaths, the mouth opens a new airway, the recorded nasal airflow drops and is scored as a hypopnea, BUT in actuality is only temporary diminishment of nasal airflow. This process might be repeated over and over leading to an accumulation of false hypopneas over a session.

There exists an easy correcting for this - ensure that the alternate airway (oral) is not available, or as you suggested sense BOTH nasal and oral airways for patients to admit to occasional nocturnal mouth breating.

Tec5 wrote: ↑

Sun Jul 03, 2022 9:13 am

We simply do not know if "they auto scored"?

Yes I made that point. Was there something else?

Let me try an analogy: On a vacuum sweeper the suction created by the blower fan creates an airflow at the sweeper head. This airflow is fairly consistant from moment to moment. However there is also a hole in the sweeper hose that allows the airflow at the sweeper head to be varied by open and closing that hole. (for example if one wanted to vacuum curtains, to avoid sucking the curtain into the sweeper). The vacuum's fan provides the overall suction (analogous to the expansion of the chest cavity), and vacuum breaker (hole in the hose) allows the airflow at the sweeper head to be varied (analogous to opening an alternate air pathway - the mouth). Measurement of only one of these airpathways (IF THE ALTERNATE PATHWAY IS IN PLAY) only provides a partial picture of the total airflow.

Maybe so, but that's irrelevant. The actual value (whether you're looking at volume or pressure) is academic because one is only looking at breaths relative to each other. Indeed, the waveforms are enlarged to the point where they can be effectively analyzed (see Auto-Fit in Oscar).

...This may be particularly significant if that alternate air passage is opened intermittently - because IMO that would open the potential for intermittent suggestions of hypopnea.

Example - for five minutes all airflow passes across the nasal cannula, then for the next three breaths, the mouth opens a new airway, the recorded nasal airflow drops and is scored as a hypopnea, BUT in actuality is only temporary diminishment of nasal airflow. This process might be repeated over and over leading to an accumulation of false hypopneas over a session.

So

1. That's pretty much impossible;

2. If it did occur then that would be something that needed looking at (because it's impossible); and

3. Hypopneas require an arousal and/or a desaturation to be scored as such. Consequently your scenario wouldn't be scored as hypopneas, they would be scored as FLBs.

Rubicon wrote: ↑

Sun Jul 03, 2022 9:39 am

Hypopneas require an arousal and/or a desaturation to be scored as such.

I respect that you administered (and scored?) thousands of sleep studies. So perhaps a bit of an explanation might be in order to understand your statement on scoring hypopneas.

As most home equipment (Dreamstation/Airsense) does not identify arousals or desaturations, the scoring of hypopneas as reported in OSCAR reports would not qualify as a hypopnea by AASM standards, Is that correct?

Said another way, the identification of a hypopnea on home equipment might suggest a hypopnea, but requires an further identification of a following arousal and or desaturation to be really classified as a hypopnea event.

All of which would lead me to suggest that flow, and desaturation, and EEG signals, read by a qualified technician is needed to clearly identify a hypopnea event.
Home equipment may overstate hypopnea events.

Tec5 wrote: ↑

Mon Jul 04, 2022 10:57 am

Said another way, the identification of a hypopnea on home equipment might suggest a hypopnea, but requires an further identification of a following arousal and or desaturation to be really classified as a hypopnea event.

As well as an EEG to make sure they're asleep. You'd be surprised at the amount of people who show up here thinking they have uncontrolled OSA, but it's simply bad sleep and SWJ.

All of which would lead me to suggest that flow, and desaturation, and EEG signals, read by a qualified technician is needed to clearly identify a hypopnea event.
Home equipment may overstate hypopnea events.

Depends on which scoring rule you use. Medicare doesn't allow the use of arousals to determine hypopneas, so all you need is a flow waveform, a pulse oximeter and the assumption that you're asleep. To your point, however, home equipment may overstate events in cases of events that are post-arousal, sleep onset, phasic REM and/or simply wake.

Hence the value in having a professional (like yourself) assess the available data.