AHI stuck at 0.0?

[archangle]

I have many nights where I have an AHI of 0.0. Most other nights it registers a 0.2. I mentioned this to my DME and he told me he was not surprised since the doctor had diagnosed me with respiratory arousals not induced by apneas. He (the DME) said that AHI cannot measure those. Is he giving me a line? (I've only been at this for 3+ weeks now so I'm still new and gullible). I did google respiratory arousals and AHI and did find articles that said the two are unrelated, and therefore AHI's do not reflect respiratory arousals. I meet with my actual sleep doctor next week and will consult with him.

Your machine can probably register RERAs, but they don't fall under "AHI." AHI only includes certain events.

You probably need to use the software to see RERAs.

[Otter]

I have many nights where I have an AHI of 0.0. Most other nights it registers a 0.2. I mentioned this to my DME and he told me he was not surprised since the doctor had diagnosed me with respiratory arousals not induced by apneas. He (the DME) said that AHI cannot measure those. Is he giving me a line?

No. While many DMEs spread disinformation either through honest ignorance or for less wholesome reasons, it is true that your machine can't measure RERAs (respiratory effort related arousals). The PR1 tries to, but given that it can't actually measure either respiratory effort or arousal, I'd take the results with a lot of salt.

[Mike6977]

The S9 units are able to determine if you're asleep or not based upon your airflow numbers as demonstrated by the wave form of your flow.


Sleeping Waveform:





Awake Waveform:

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When I first awaken, I've tried holding my breath for more than 10 seconds, either on the inhale or after the exhale.

Then I stay still for 5 minutes, continuing my slow, sleepy breathing patterns even though I am awake.

For me, in ResScan, such bogus "events" are consistently recorded as apneas on both my S9 and S9 Auto.

So, by my experience, I'd say no, the machine can't reliably tell if you're awake or asleep.

_____________________________________________________________________________________________________________

it is true that your machine can't measure RERAs (respiratory effort related arousals).

But I think that watching your flow at close resolution can (2 seconds or less), can help you establish a likely pattern, not very granular, but perhaps enough to consider changing your pressure management.

It may also be useful in establishing better sleep hygiene (i.e. regular aerobic exercise).

I wake up 2 to 3 times during the night. When this happens, I get up, have light snack, read or watch TV, a break typically lasting 30 to 40 minutes. Then I try to go back to sleep.

Reviewing the flow at close resolution the next morning, it seems possible to get a "feel" as the waveform moves from the top example (sleep) to the form more closely resembling the more sinusoidal example (awake).

You can look at sub-clinical obstructive or central events ( <10 seconds ) seeing the flow flatlining, immediately followed by the distinctive ResMed FOT "squiggle".

It's interesting to see how your breathing pattern does/ or doesn't change after those sc events.

The most obvious example for me is waking up right after such a sub-clinical apnea. Would that qualify as a RERA?

Or are RERAs limited to EOG, EEG, and EMG measured changes in sleep depth (following a change in readings from flow and/or the thoracic and/or abdominal belts), that don't result in a full awakening, but may result in sleep fragmentation?

[kongjie]

Thanks to everyone for the numerous replies. The old turn it off and on trick worked. I don't know why I didn't do this first before posting as it seems as every element of our lives gets chipped that it is the first step in diagnosing problems. Except with airplanes, I suppose.

[Otter]

it is true that your machine can't measure RERAs (respiratory effort related arousals).

But I think that watching your flow at close resolution can (2 seconds or less), can help you establish a likely pattern, not very granular, but perhaps enough to consider changing your pressure management.

What does a RERA look like in flow data?

[Mark184]

Newbie chiming in again. Good to hear the confirmation about AHI and RERA's. As I mentioned before, when I spoke to my DME and was alarmed that I was getting lots of 0.0 AHI's, he said the S9 data, even viewed in Rescan does not provide data that conclusivley indicates RERA's at all, but he told me that the flow rate can be viewed as a direct response indicator. I'm just repeating what he told me. I see the doc next week, and I'll certainly be asking for more info. These posts are quite helpful. Thanks everyone!

[archangle]

What does a RERA look like in flow data?

Good question. I don't see anything that looks obvious when I look at my waveforms.

[Mike6977]

What does a RERA look like in flow data?

Good question. I don't see anything that looks obvious when I look at my waveforms.

Never said anything about "obvious", quite the opposite:

can help you establish a likely pattern, not very granular

For me, a RERA looks like a sub-clinical obstuctive or central (and I deduce, not know for sure, an increase in respiratory effort), followed by a change to sinosodal, followed by me waking up. I'd say waking up is "an arousal from sleep", yes?

http://emedicine.medscape.com/article/295807-overview

I didn't say I could definitively read respiratory effort caused shift-level changes in my REM or non REM sleep (that didn't lead to an immediate awakening) just from my flow chart. I'd need a sleep lab study to do that. Didn't mean to leave that impression.

[Slartybartfast]

Maybe the word "infer" would be useful. One can infer from the data, specifically the flow peak shape, whether the user is asleep or awake following an event. The machine can't tell that, but someone who knows what the waveforms look like can make an educated guess, or inference, as to what the state of the CPAPee might be. It's not definite, but lacking an EEG lead, it's the best one can do.

FWIW, I get a 0.0 about once/week, with others being 0.1, 0.2, 0.5. The 0.0s seem to coincide with zero leakage rate nights. On nights when my mask leaks a little and I can't get it adjusted just right the AHI seems to run a little higher. I think in my sleep part of me is aware that the leak needs fixing but I don't care quite enough to wake up and make it right, and that reflects in how I feel the next day.

[Mike6977]

Maybe the word "infer" would be useful. One can infer from the data, specifically the flow peak shape, whether the user is asleep or awake following an event. The machine can't tell that, but someone who knows what the waveforms look like can make an educated guess, or inference, as to what the state of the CPAPee might be. It's not definite, but lacking an EEG lead, it's the best one can do.

Like I was saying, but a sleazy combination of being better worded and much more concise.

FWIW, I get a 0.0 about once/week

No joke: I sometimes get 0.0s when I've had too many Tullamore Dews just before sleeping; it's against conventional wisdom and completely counter-intuitive, but somehow true.

The 0.0s seem to coincide with zero leakage rate nights.

And for me, mask leakage is the bane of my SDB management. I'm going to try scuba diver's silicone on my Activa LT, see if that helps.