"please keep me updated about oximeters "
Sleep Apnea Forum Bringing Power to the Patient
New? Free Sign Up
Then check our Welcome Center to a Community Caring about Sleep Apnea diagnosis and Sleep Apnea treatment:
CPAP machines, Sleep Apnea surgery and dental appliances.
CPAP Supplies
Latest Activity
AHI vs. AI and HI
I was going to post in another thread about the usefulness of AHI, but I thought I'd start a separate one for this question.
My CPAP stats are pretty consistent, in that the AI numbers are fairly low, in the range of 0.0 to 0.5 on a typical night, though it's gone as high as 1.7.
On the other hand, the HI numbers are usually much higher, in the range of 5.0 to 11.5.
I can't seem to find any reason for the hugher HIs.
I originally thought it was due to leaks, which typically are around 0.4 to 0.6, but that doesn't seem to be the case.
Over the years I've taught myself to do deep breathing, and to slow my breathing down when I go to sleep, in order to relax.
Does anyone have an idea if this HI range is normal, or high?
If it's high, is there an explanation as to why it is high?
On a (possibly?) unrelated note, in the last week I've been feeling more tired during the day. I've started with a new mask, but I'm not sure if that has anything to do with it.
Thanks!
Views: 1609
Replies to This Discussion
-
Permalink Reply by Henning on
-
I agree with Jeff. Forget all about your HI
.
At a time I called ResMed with the same issue. They told me that my ResMed S8 Autoset II counts my HI's but they were treated. It was only my AI I should take care of.
ResMed is known to over count Hypopneas.
Henning
-
Permalink Reply by RockRpsgt on
-
Ok, so how can we accept that the algorithm only works for part of the problem? This makes no sense to me. A partially treated airway will stop throwing out apneas and begin tossing hypopneas.
-
-
A home machine is not a PSG. Just because a home machine estimates that you may have had a hypopnea does not mean you actually did have an event that would have been counted as one on a PSG. The machine only has one channel to monitor and uses a proprietary method of interpreting that channel.
It is all about flow limitation jnk. if the machine can't accurately determine hypopneas, then how can we trust it to be accurate on apneas? I understand that the machine is not as accurate as a PSG. My question is can it determine flow limitation or not? It does not sound like it can. This leads to even more questions on the validity of the Resmed auto-pap system.
The issue has nothing to do with treatment, though, Rock. It is only about how a machine REPORTS on itself. And it is better for a machine to give more information rather than less information.
Bad information is never good. No matter the amount. The issue has everything to do with treatment. People are spending the hard earned money to know this information.
-
-
Don't get hung up on the fact that a PSG has something IT calls a "hypopnea" and each brand of machine chooses something that it calls a "hypopnea." One is based on a complicated definition involving more than one channel of information. The other is based on interpretation of one channel. BOTH are useful information, as long as we are smart enough to keep in mind the differences.
This to me is part of the problem. A hypopnea is a hypopnea no matter how you look at it. The fact that one manufacturer defines it one way and another completely different only adds to the problem. A PSG only uses 2 channels to measure hypopnea, and one is built into the machine itself. By the way a PSG does not call a hypopnea anything. It is the job of the scoring tech to determine this.
The numbers are for trending, meaning that you use them to see if you are getting worse numbers or better numbers over time. The purpose of a home machine's information is trending, NOT judging success.
Would not watching to see if your numbers were getting better or worse be judging success?
-
-
Yes, the machine monitors changes in flow, and does so very, very well. In fact, it does it so well, that it may (as is the case with the S8) report changes in breathing that might be ignored in a sleep study.
The software will also count events such as sleep onset and arousal based events as well. Whiole I do not count any event as insignificant, there are some that should not be included in AHI.
-
Permalink Reply by Mary Z on
-
Thanks henning, Rock, and j n k, this is a big help in how I look at my numbers every morning. I can tend sometimes just to have a naturally low respiratory rate, which might account for a high AHI and a much lower AI.
-
Permalink Reply by Andy on
-
Hi all,
Thanks for all of the replies. I didn't realize this question would get so much good discussion!
I am still using my ResMed AutoSet II S8. However, it is not set to automatic, but is set to a fixed pressure.
Now, it makes sense that the unit treats the HI, and subsequently reports the HI as well. That's somewhat confusing, in a way, since I'd expect that if it treated something it wouldn't still count it.
Of course, it's a valid approach-- if they tell us that's what they're doing!
So, even after all of this, I'm not sure if you're saying that the HI reported has also (likely) been treated, given that my machine is set to fixed?
I have not been worrying about the HI numbers all along, because somebody had mentioned that they're not as important to me as the AI numbers.
I'm happy that the AI numbers are failrly low, of course.
I guess the next question would be: How much variation in AI numbers is reasonable. They do tend to jump around from night to night...
-
-
No where in any of my post did I compare the machine data to the PSG data. jnk you are the one hung up on this. There is no comparison. One is a software based algorithm, and the other is a computer based study monitored by a human. My point is that the machines should look at events the same across the board. A hypopnea on a Resmed should be defined in exactly the same way on a Respironics, or any other machine. There is no reason why Judy should get different results from a respironics than from her Resmed, or vice versa. We are taught that both machines do the same job. If you had your PSG scored by 2 different labs and got 2 different results you would be pretty confused.
j n k said:Trending information is what it is. It is not directly comparable to info from a PSG or another brand of machine.
It really is not a "problem" that different definitions are used, as long as you take the time to learn the definitions and act accordingly.
Desats and arousals are not monitored by home machines. The point is, that's OK, because they don't need to be. One channel (flow) is good enough for trending.
Just don't take that one-channel trending data and attempt to use it to compare with a PSG or another brand (or in ResMed's case, newer model of the same brand) of machine, and everything will be fine.
:-)
-
-
I am sorry to have ever doubted you jnk. I keep forgetting that you are the one that study these things everyday. I did not assume anything, or I did I realize that your opinion that I was comparing anything made it so. I did intentionally compare the PSG and the home data in my last response. I find it funny that you are so quick to point out the faults of the labs, techs, and docs. Yet when someone points out the fault of the machines you get so defensive. I think it is time for me to take a break from sleepguide.
-
-
Andy, (also for Jeff and Rock)
When you use your APAP with a fixed pressure, I am not sure that your "Hypopneas" are treated. I think you should talk with your sleep doctor. IMO it is better with APAP settings.
But the whole discussion about ResMed and AHI is more complex than that. My first post in this discussion was the short one.
Although ResMed S8 counts HI then ResMed don't use the term “Hypopneas” in their algorithm. They use instead the terms "flow limitation, snore and apnea, where the" flow limitation "is the closest they come Hypopneas.
Here is a link to an article from ResMed (introduced by Judy)
http://www.sleepguide.com/profiles/blogs/resmeds-development-of-the
In a different context, I have heard the term "partial Hypopnea" instead of the term "flow limitation." Maybe that's why ResMed counts more HI.
Another Interesting information is that ResMed S8 NOT responds to apneas when the pressure is above 10 cmH2O.
Henning
Andy said:Hi all,
Thanks for all of the replies. I didn't realize this question would get so much good discussion!
I am still using my ResMed AutoSet II S8. However, it is not set to automatic, but is set to a fixed pressure.
Now, it makes sense that the unit treats the HI, and subsequently reports the HI as well. That's somewhat confusing, in a way, since I'd expect that if it treated something it wouldn't still count it.
Of course, it's a valid approach-- if they tell us that's what they're doing!
So, even after all of this, I'm not sure if you're saying that the HI reported has also (likely) been treated, given that my machine is set to fixed?
I have not been worrying about the HI numbers all along, because somebody had mentioned that they're not as important to me as the AI numbers.
I'm happy that the AI numbers are failrly low, of course.
I guess the next question would be: How much variation in AI numbers is reasonable. They do tend to jump around from night to night...
-
Permalink Reply by Judy on
-
ROCK HINKLE!!!!!! You dang well better NOT take a vacation from sleep guide!!!!! We ALL need you. Including jnk who thinks as highly of you as the rest of us do. Gracious, you must be overtired today. So .... I'm sending you lots of ((((hugs)))) and giving you an order to get your bottom to bed and get some sleep.
© 2025 Created by The SleepGuide Crew.
Powered by
