What is "good" AHI?

I know this question is akin to asking "how long is piece of string".

I was diagnosed w/ a AHI of 31 (severe). The second sleep study indicated my pressure should be 8 cm. Given the severe AHI, I was a little surprised my prescribed pressure was so low knowing machines run from 4 to 20-something. Have since figured out that non-CPAP AHA doesn't necessarily directly relate to the required pressure with CPAP.

After reading on this forum, I really wanted the M-Series Auto w/ Encore Pro to help me track progress and the C-Flex/Auto seemed like very nice features. My DME was ready to give me the bottom of the line M-Series, but I got my doctor to add the magic words "8 - 12 cm" on the script . I also had him add "with auto altitude adjustment" since I travel 80% of the time. Secretly, I knew if the DME/insurance balked at APAP, they would at least give me a M-Series Pro with C-Flex and Smart Card since the lower models didn’t include auto-altitude. The DME got me a M-Series Auto with no issues, but did pull me aside before his group training class and request that I ask questions about C-Flex and Auto afterwards in private. I think he didn’t want a revolt with the other patients once they figured out my machine was more advanced. Sorry, off topic.

My average AHI is 3-4 with a couple lows around 2 and occasionally a high around 7. What is a "good" AHI with CPAP? I imagine this will vary wildly between people, but how low of AHI could I expect if everything is perfect? In other words, if someone didn't have OSA and was in great health (no smoking, good weight, eat right, no drinking, blah, blah), what would their AHI run between? Zero? I could see young buck Joe Blow not having a Apnea event, but wouldn't everybody have an occasional Hypopnea event?

Or maybe what's more important, what is an upper AHI that I should be concerned about? At what point should I do some investigation?

The techie inside me enjoys tracking all the stats, but I don't want to "chase rabbits down holes" or fret unnecessarily.

Any AHI under 5 is great. That's considered normal. I like to shoot for zero, and I get them a couple of times a week. It really depends on how you feel. An AHI of 2 or more and I'm feeling it.

Brenda

Ditto what Brenda said. An AHI of 5.0 is considered "normal". W/in that range you would prefer to see the HIs outnumber the AIs rather than vice versa. And, of course, a 0.0 for BOTH would be .... Utopia? But pretty darn unlikely!!!!

Not to hijack this thread but can you guys tell me if I'm reading this right?

Compliance (h/d): 10h01min
Apneas : 6
Apneas/CA : 4
Hypopneas : 1
Hypopneas (FL): 1

So over the 10 hours, I had 10 AIs and 2 HIs, for a total AHI of a bit over 1? Which isn't bad?

What's the diff between the diff Apneas and diff Hypo's? I'd guess an Apnea/CA sounds worse to me then just a plain Apnea and yet I would expect that to count as worse in the overall "how bad is your apnea" guides.

My average AHI after 4 months was 5.2 with AI of 1.1 and HI of 4.1. Much of that four months was experimenting. I can see myself getting to 3- 4.0 average AHI but not to Zero.

[quote="MrPaul"]Not to hijack this thread but can you guys tell me if I'm reading this right?

Compliance (h/d): 10h01min
Apneas : 6
Apneas/CA : 4
Hypopneas : 1
Hypopneas (FL): 1

So over the 10 hours, I had 10 AIs and 2 HIs, for a total AHI of a bit over 1? Which isn't bad?

What's the diff between the diff Apneas and diff Hypo's? I'd guess an Apnea/CA sounds worse to me then just a plain Apnea and yet I would expect that to count as worse in the overall "how bad is your apnea" guides.

There filled it in. I'm pretty sure those are nightly numbers, not hourly, since there's a column right next to it that's labeled Index/h.

Here's that page of the report

MrPaul wrote:There filled it in. I'm pretty sure those are nightly numbers, not hourly, since there's a column right next to it that's labeled Index/h.

Here's that page of the report

Hi MrPaul,

Check your PM.

SithLord,

The issue of AHI is a little more complex than it looks.

AHI is made up of two parts ...
1) The AI (Apnea Index) these are 'events' scored as Apneas (blocks)
2) The HI (Hypopnea Index) these are 'events' scored as breathing reducing by 50% in 10 secs (some clinics argue that to be a true Hypopnes, an SpO2 destauration must also be present - a desat is normally taken to be SpO2 % dropping by 4% in 10 secs)

Then there are 'Flow Limitations' these are like Hypopnea wannabees - breathing reduces but not enough to be scored as a Hypopnea.

The other problem is that no two brands of Auto are likely to score you the same. Their algorithms differ enough that there is no real common science to the AHI numbers produced. Thus, the AHI score incl AI & HI components, should always be treated as relative to the brand of machine you haev & not always the same as a similar number from another brand of machine.

For example, Respironics machines may score AI of say 2.5 & HI of 0.8 when for the same person during that same period of sleep, a Resmed machine may score an AI of 0.9 & a HI of 3.0. Both differ quite a bit over their interpretation of HI in particular.

That in itself is not a problem, it just means that AHI (AI + HI) scores are best compared with the same brand of Auto and progress best measured against the same brand.

Some interesting effects re sleep & cpap are that many people when they 1st go to sleep, go through an approx 30+ mins of adapting to sleep & sometimes stopping breathing for periods of 10-15 seconds. This is pretty normal. If someone yawns, they may stop breathing afterwards for 10+ secs & yet there is nothing wrong, but that slowdown may be scored as a Hypopnea. Some machines allow the RT to set a delay (settling period) where the machine ignores events for a period of time. This is in recognition of how the 1st hour can skew the overall AHI score with essentially false data.

Good luck

DSM

SithLord, any AHI under 5.0 is doing fine, and would be "normal." "Normal" people (don't need treatment for OSA) can have a few events each night, including some central apneas and be getting normal, refreshing sleep.

That doesn't mean other things can't disturb sleep. Med side effects, other underlying health problems, poor sleep hygiene, etc. You can have arousals that knock you out of whatever stage of sleep you're in at the moment...arousals that have nothing to do with an apnea or hypopnea.

So, a low AHI isn't everything involved with getting good, restful sleep. But getting OSA under control is definitely important, and an AHI under 5 is good.

There's no particular extra benefit in getting an AHI of zero, other than the fun of seeing that occasionally on the data. I feel just as rested at AHI's of 1, 2, 3 (and even 6 one night!) as I do when I see zero.

SithLord wrote:The DME got me a M-Series Auto with no issues, but did pull me aside before his group training class and request that I ask questions about C-Flex and Auto afterwards in private. I think he didn’t want a revolt with the other patients once they figured out my machine was more advanced.

ROTFL!!! Yup, he didn't want a revolt on his hands. He wanted the cattle to leave peacefully.

Mr. Paul,

So over the 10 hours, I had 10 AIs and 2 HIs, for a total AHI of a bit over 1? Which isn't bad?

That's the correct interpretation. I wonder if your settings should be tweaked a bit to lower your Apneas. I'm no expert, but if your apneas are occurring when your pressure maxes out, then maybe a higher upper limit would allow the GoodKnight to eliminate them. Just a thought.
Cathy

dsm wrote: Some interesting effects re sleep & cpap are that many people when they 1st go to sleep, go through an approx 30+ mins of adapting to sleep & sometimes stopping breathing for periods of 10-15 seconds. This is pretty normal. If someone yawns, they may stop breathing afterwards for 10+ secs & yet there is nothing wrong, but that slowdown may be scored as a Hypopnea. Some machines allow the RT to set a delay (settling period) where the machine ignores events for a period of time. This is in recognition of how the 1st hour can skew the overall AHI score with essentially false data.

DSM,

It's interesting to see that since most of my events happen at the very beginning of the night. Then settle down about an hour into sleep with very few events! Well, that makes me feel better

Linda

FWIW, my OAI is approx. 1 of the total 3-4 AHI. Which seems like the more important index compared to HI.

Some machines allow the RT to set a delay (settling period) where the machine ignores events for a period of time.

Interesting. Does anyone know if the M-Series ramp function doesn't collect data during the period?