why is less than 5 AHIs the magic number?

[nmevan]

greetings

I was clocked at 53 AHIs per hour during my sleep study

wouldn't anything less while using my auto bipap machine be beneficial?

I'm down to averaging 5.3 AHIs per hour

why is less than 5 the holy grail?

thanks

evan

[cflame1]

If you get less than 5 AHI on a sleep study, then insurance won't pay for treatment usually.

[nmevan]

aside from the insurance aspect...

I've read several times on the forum that one cannot feel fully rested unless their AHIs are less than 5...some say even less than 2

what's up with that?

evan

[JohnBFisher]

It essentially has to do with conconcept of diminishing returns. The basic idea of diminishing returns is that to address the basic issue we put x amount of work into the system. That will resolve all but a small number of issues. To solve those remaining issues takes a LOT more effort.

So it is with people and apnea. To resolve most apneas CPAP works. For some people we need to move to BiPAP. And it requires moving to more and more sophisticated and costly technology to reduce the apneas further than the 5 per hour.

And remember, we are living beings - subject to lots of variability. Not machines. So it is perfectly normal for most people to have an apnea every now and then. Perhaps it's as a result of rousing enough to be lightly awake. Then as you drift back asleep you have apneas. Or perhaps it's a result of sleeping on your back. Or perhaps it's from tossing and turning.

Some are fine. Many are not. So, why 5 per hour? I don't know if there's a hard and fast reason other than that amount means a few are allowed, but not so many that it severely disrupts sleep. 5 or less means that you have less than one every 10 minutes. 6 or more means that you averaged an apnea once every 10 minutes.

Other than that reasoning (for the frequency and the fact that some are perfectly normal), I am not certain there is a specific reason for 5 as the boundary. However, it does seem to help differentiate between those who suffer the impact of apnea and those who do not.

[elena88]

most people who are really into it I have seen try to keep their ahi under two or one if they can..

they can FEEL the difference..

how do you feel?

I cant feel the difference between 0.0 or 8.0 but most everyone else can so they work on getting low numbers..

[Janknitz]

Remember the Cosby episode "Why did we only have four children?" "Because we didn't want five." (that was before they added the character of the older daughter who had been "away at college").

Five is a bit of an arbitrary number. If you look at scales determining apnea, 0-5 is considered "no apnea". So it's an arbitrary designation for "normal". They had to set it somewhere. 10 is too high, 2 is too low since some of the so-called "normal" population will have AHI's higher than 2 but less than 5.

The big difference is how you feel, but you are not feeling different one way or another. I don't know what to say about that. I had 77 AHI on testing (and I thought it was one of my "better" nights, LOL.). I don't feel dramatically different at less than 1.0 AHI, but I do feel better. I've never had an 8 or a 12, so I don't know how I'd feel then. Seems like it should be better than 77, but who knows. Shrugging my shoulders here.

The theory, I guess, is that you are not damaging your body at less than 5, but when you get over that limit you may be, even if you don't feel it. Just like blood pressure. The numbers for "normal" are somewhat arbitrary, but it's something to shoot for, because statistically you will have less sequelae the closer you are to the arbitary "normal". Remember, you do not necessarily feel the ill effects of the damage high BP is doing to you, but it's damaging you just the same. I think SA is a lot like that. By the time you notice the symptoms, a LOT of damage has already been done.

[kempo]

I have been at it now for over 4 months. Every once in a while I know it's going to be over 5 before I look. I am usually between 1.5 and 3.5. Three days ago when I woke up I knew by the way I sleep and by the way I felt it was going to be over 5 and sure enough it was 8.2. I didn't really feel that bad. I just didn't feel I had enough rest.

Anyways, If I were you I wouldn't panic with a 5.3. I would just continue to make minor adjustments.

[jonquiljo]

I dunno ... I am usually between 0.0 and 1.0 - generally closer to 0.3. When I have a 0.6 or higher night, I feel like crap the next day. But I am usually lucky to get 6 1/2 hours sleep - so perhaps I am pushing it??

I think all of this is arbitrary. The AHI of 5 is an insurance number and I expect that most people with an AHI of 5 could benefit from going closer to 1 - or even 0.

[Laurie1041]

Hi Evan,

I am all about evidence-based practice and statistical analysis of data. But that's my background and preference. Some go with the flow and some question why. Your questions are excellent and make people think and maybe ask themselves, "Why? Where's the evidence?"

I think your doctor will be thrilled with your results. I am still searching, but as of yet, I have not found 1 journal article that mentions that 5 AHI's is the magic number. Instead, I direct you to the Medscape interview with Christian Lattieri, M.D. who states, "CPAP is the most effective and most widely used treatment for OSA, and approximately 95% of people will have a 90%-95% reduction in their apnea hypopnea index.

For the vast majority of people, this provides adequate therapy.

So I believe you have met this goal. At your next appointment, I would ask your doctor what his or her goal is with respect to AHI reduction. Also, if you are having difficulty with the pressure setting of 13 cms, you may want to talk to your doctor more sooner than later. You could certainly ask the good folks on this forum if they have found ways in which to manage high pressures. Start a new topic, if you would like. I think there are probably several different solutions to this problem. All the best, Laurie

[billbolton]

I don't have the citation handy (though I have cited it previously).... anyway, the 5.0 or lower number being the normal sleep range is based on published standards from at least one of the members of the World Federation of Sleep Research & Sleep Medicine Societies (probably by the American Academy of Sleep Medicine) and is backed by substantial clinical research.

Perhaps someone with more time than I have right now can chase it up

Cheers,

Bill

[idamtnboy]

"Just because!"

Seriously, like the others have said it's most likely somewhat arbitrary based on diminishing returns as John explains above.

[LinkC]

John and Bill have it pretty well pegged. While it's not entirely "arbitrary" (i.e. there's some thought behind it), getting your AHI </=5 AHI is considered "effective therapy" by the industry. It's a goal to shoot for.

That being said, many of us set a personal goal of ALARA (As Low As Reasonably Achievable).

[SleepingUgly]

I honestly read somewhere (don't remember where) that a couple of the big wigs couldn't agree, so they compromised on 5. I don't know if that source was reliable or not. Even if 5 was determined by research, it is always 5 +/- something, as we can't measure anything perfectly. So if you felt great at 5.3, I certainly would not obsess about the difference between 5 and 5.3.

[The Guest]

An AHI of 5 or less is within the normal sleep range. There are a few other physiological reasons for apneas beside obstruction. For example the normal transition from wake to sleep often results in a central apnea. This might cause an arousal to breath and of course when you go back to sleep that transition causes another central apnea. Any time you wake up throughout the night you likely will have one or two of these 'sleep onset central apneas.' Often when we turn over our breathing pauses and this can cause apnea. Occasional leg/arm movements and teeth grinding may cause apneas. Or they might cause you to wake up and again have sleep onset centrals. These are normal parts of sleep until they reach a number that is too much for you individually, generally above 5 per hour.

[jlk]

Hey, are we talking 5 per hour or 5 per night? I know I am doing good, but with .3 on resscan 3.11 per night, I must be doing great. Sorry for those with 5 or more per hour, sounds like some tinkering is in order. I have .7/.8 once or twice a week, usually mixed apneas, can't figure out exact cause. My main problem at this point is waking up after3-5 hours, if my mind starts the day, sleep don't happen for the rest of the night. Part of my problem is late night snacks, just ate about a pint of really good (hot!) home-made salsa, going to pay for that in more ways than one! Looks like a tylenol pm night. john