Importance of AHI

[pine3874]

Is AHI the only data one has to be concered with as long as it is <5?

[HoseCrusher]

It depends on if you are talking about sleep study scored AHI or xPAP machine scored AHI...

If both are less than 5, then you are no longer experiencing obstructive sleep apnea.

[LSAT]

You should be concerned with your O2 levels, but if your AHI is < 5 chances are the O2 is ok.

[ameriken]

Is AHI the only data one has to be concered with as long as it is <5?

Watch the leak rate because large leaks will throw off the therapy and the data.

[robysue]

Other things to watch:

Total sleep time: If you are not sleeping with the mask on having the mask on is not helping as much as it should.

Sleep efficiency = (time asleep)/(time in bed): If this is consistently below 80 o 85r%, chances are you won't feel all that rested.

Neither of these are technically OSA-related, but if you're experiencing night after night of insomnia when on xPAP, then chances are you're not getting maximum benefit (in terms of restful, restorative sleep) from you CPAP machine.


And though it cannot be quantified, there's the all important qualitative data generated by: How do you feel day after day and night after night?

[avi123]

Is AHI the only data one has to be concerned with as long as it is <5?

Not really. Some one could have an AHI of 10 to 15 (epecially from our home CPAPs vs PSGs) and feel fine and someone else with an AHI below 5 who feel sicker than hell.

Check this:

http://www.respiratoryreviews.com/sep02 ... Index.html

and this:

http://www.thehealthcarecenter.com/apne ... index.html


Controlling the following comorbidities is MORE important:


http://www.resmed.com/us/clinicians/abo ... clinicians

[Cuda]

I agree with Ameriken, leaks seem the number one thing to look at. My summary on the machine may say AHI 5 or less but looking at the detailed data I can show massive leaks all night long and the machine is not recording any events. I do not trust the cpap numbers at all with leaks over the recommended amount.

[archangle]

AHI is probably the best single number to look at. I can't think of a better single number to look at.

On this board, we tend to berate the overemphasis "the system" seems to put on AHI, because it's only part of the story. To me, the biggest drawback of AHI is that it rates all apneas the same. For instance, an 11 second apnea counts the same as a 120 second apnea. The effect on your body is not the same.

I think everyone should get a fully data capable machine and use the free software to look at their data occasionally. Looking at the waveforms for your events gives you a lot of info if you put some thought into it.

[DoriC]

Right now and until someone comes up with a different standard, an AHI <5.0 is considered adequate therapy although most people need it lower most of the time to feel really rested. I don't see how anyone can feel fine having 10-15 events per hour with inadequate therapy. The machine can compensate for some leaks but when there's too much the AHI cannot be relied on. I have personally observed my husband having some events while his mask was really leaking before I could get to help him adjust his mask, and the data did not score them.

[moresleep]

For all the reasons stated above AHI is not always a reliable indicater of how one is doing on CPAP. If it were me (and it has been), if I had an AHI <5 and still had trouble sleeping or displayed daytime symptoms, I would (1) check for mask leaks and get those under control, and, if still not doing ok (2) get a recording oximeter and look at the graphs to see if O2 and heart beat stayed within acceptable ranges. Unfortuantely, after that, it gets complicated

[avi123]

I agree with Ameriken, leaks seem the number one thing to look at. My summary on the machine may say AHI 5 or less but looking at the detailed data I can show massive leaks all night long and the machine is not recording any events. I do not trust the cpap numbers at all with leaks over the recommended amount.

Reply:


In your case by using an S9 Autoset you don't need to be concerend with mask leaks if it's below 24 L/min. The Rescan graphs show the leaks all along the time that the machine is on. Even if you run into "massive leaks" the machine will analyze the event as "Unknown".

See here a Rescan graph from an A9 Autoset that shows several "Unknowns" events due to mask leaks that I created on purpose:

The following "Unknown" events (yellow flags) were created on an S9 Autoset in CPAP mode by allwoing my mask to leak:



The AHI graph shows a value of 14.6 which includes the 3.5 Unknowns b/c of the leaks.

In the following case the "Unknown" events (yellow) were due to unitentional leaks. But I know not to relate to them.