[Treatment] Is AHI misleading?

[SamWong2012]

I downloaded my VPAP smart card data with Rescan and did an analysis. The summary reports seem OK, my AHI ranges from 3 to 8, but when I look at the details (event, AHI diagrams), I have many "events" that last from 10 seconds to 50 seconds throughout the nights. AHI is averaged over 6-8 hours, I wonder if AHI in the summary report is misleading. I attached a file in MS word 2007 docx format (a typical night's data) to show my questions: Is AHI misleading? Is my VPAP therapy really working?

[PaulaO2]

Why do you say the AHI is averaged out of 6-8hrs?

The AHI is the total events divided by the number of hrs slept. In this report, that would be 8.54 hrs. So to reverse math it, 7.1 x 8.54 = 60.654 events that night. Is that what the other reports say?

There are a lot of people who feel we put too much emphasis on the AHI. That it's not the only thing involved in determining adequate sleep was reached.

How do you feel? Do you feel rested?

If you do, then yes, the VPAP is working. If you do not, then either it is not working or there is something else going on.

[Rritch]

I downloaded my VPAP smart card data with Rescan and did an analysis. The summary reports seem OK, my AHI ranges from 3 to 8, but when I look at the details (event, AHI diagrams), I have many "events" that last from 10 seconds to 50 seconds throughout the nights. AHI is averaged over 6-8 hours, I wonder if AHI in the summary report is misleading. I attached a file in MS word 2007 docx format (a typical night's data) to show my questions: Is AHI misleading? Is my VPAP therapy really working?

Sam,

an AHI of 5 or less is considered normal. If you have having typical AHI in the 7 range that would still be considered mild OSA. You may want to consider talking with your Dr. about making adjustments to your treatment to try to reduce your AHI further.

[Sleepster]

AHI is averaged over 6-8 hours, I wonder if AHI in the summary report is misleading.

The AHI can be misleading. It's the (average) number of apneas or hypopneas per hour. To count, each of these events must last for at least 10 seconds.

The issue is whether or not these events are associated with an arousal, or a significant drop in blood oxygen level, or both. You would need more equipment, such as that used in a sleep study, to answer these questions.

The important thing is that you monitor your AHI and report to your doctor any concerns you have. If CPAP therapy cannot get your AHI below 5, or if you're still not feeling well after several months of therapy, you should discuss with your doctor the possibility of another sleep study.

[jdireton]

Sam,

I agree with everyone that the first question is "How do I feel?" That said, a pulse oximeter can be a great additional source of information. I have found when I have long duration events (> 20 seconds), the O2 sat still gets really low (~70). Luckily, these are infrequent but I can correlate the "bad mornings" with longer or quick multiple events.

I'd like to see how the O2 sats are without CPAP but I'm not brave enough to go a night without it!

[zonk]

Is AHI misleading? Is my VPAP therapy really working?

Prof Colin Sullivan the inventor of CPAP doesn't regard AHI useful and he said the following;
Probably the best indicator of SDB, however, is simply the response to continuous positive airway pressure (CPAP) treatment.
"It really is a no-brainer," Dr. Sullivan remarked, pointing out that CPAP administration is especially easy with the newer devices that automatically set the appropriate amount of positive pressure.

[Dawei]

Sam--Comments above make some good points in my view. Along with what others have already said, I can tell you that since recently starting to use an AutoSet (first on loan and now one of my own), I have seen that I have an unexpectedly wide variation of sleep experiences over time. One night can produce an AHI of 2 and the following night it might be several notches higher, even up to something around 12! I'm beginning to learn that things like mental/emotional state as well as the number of hours of sleep as well as the time of evening when I go to bed all seem to somehow have an influence on how mentally relaxed I am and possibly this affects my AHI numbers for that night.
This is possibly why the sleep doc I see wants to see my AHI numbers for a period of time, not just for one, two or a few nights' sleep.

[SamWong2012]

Why do you say the AHI is averaged out of 6-8hrs?

The AHI is the total events divided by the number of hrs slept. In this report, that would be 8.54 hrs. So to reverse math it, 7.1 x 8.54 = 60.654 events that night. Is that what the other reports say?

There are a lot of people who feel we put too much emphasis on the AHI. That it's not the only thing involved in determining adequate sleep was reached.

How do you feel? Do you feel rested?

If you do, then yes, the VPAP is working. If you do not, then either it is not working or there is something else going on.

Do I feel rested? Sometimes I feel very well, but not all the time. I cannot draw any correlations between low AHI levels and feeling well. I am thinking about getting a pulse oximeter, as recommended by a few members. I see some finger pulse oximeter on sale for $50, can I use them? I appreciate some inputs on the subject. Thanks

[PaulaO2]

Oximeters are good but only if it can record the data and let you view it on your computer. Several of us have the CMS-50D which is available from Supplier 19.

http://www.apneaboard.com/forums/Thread-...plier-List

It is a very cheap model but it works. I've not had any issues. The software has given some people grief.

http://www.apneaboard.com/wiki/index.php...SleepyHead

http://www.apneaboard.com/wiki/index.php...2_software (still in progress but enough there)

[JumpStart]

.... Several of us have the CMS-50D which is available from Supplier 19.

I believe Paula means the CMS-50D Plus, which is the non-medical device. The CMS-50D is the FDA approved item, which is more expensive. I think.