High HI - what would cause this?

allisonandrews · Post by **allisonandrews** » Mon Jan 28, 2008 10:30 am

Until Resmed comes out with Vista compatible software, I am stuck just using my LCD readout on my S8 Elite.

Last night's numbers:
Pressure - 8 (Titrated pressure = 9)
Leak - 0.0
AHI - 7.1
AI - 0.3
HI - 6.8

What do you think could cause my HI to be so high, yet my pressure stayed at 8? I know I was coughing a lot last night. Would this affect just the HI?

Country4ever · Post by **Country4ever** » Mon Jan 28, 2008 11:33 am

Hi allison,
I'm assuming you are on APAP? What is your lower pressure set at?
Do you lay in bed awake before you sleep and after you wake up with your machine on? Being awake can make your AHI look higher, even though you don't seem to be doing any abnormal breathing.
Let us know what your settings are.
I'm discovering that I have fewer hypopneas if I don't have too wide a range between my two pressures.

allisonandrews · Post by **allisonandrews** » Mon Jan 28, 2008 12:57 pm

Sorry, no just straight CPAP set at 9. I didn't put on my mask until a few minutes before I went to bed, but I did have a few strong coughing fits last night. It seems to be the only thing "different" from normal.

krousseau · Post by **krousseau** » Mon Jan 28, 2008 1:07 pm

The pressure needed to eliminate apneas is lowest, the pressure needed to eliminate hypopneas is higher, and the pressure to eliminate UARS is even higher. So the pressure you use to eliminate apneas may not be enough to eliminate hypopneas. When I tweak my pressures to reduce hypopneas I raise my lower number and keep my upper number 1-2 cm's H20 above my titrated number. I'd like to have my lower number even higher than I do and keep a narrow range but have problems with aerophagia. Am in process of moving to a BiPAP and going through some trials of other interventions to assure qualifying for reimbursement of the BiPAP.

I think being awake while on the machine would make your numbers average out LOWER since you are less likely to have breathing events while awake. Total events get averaged over awake time + sleep time instead of just sleep time.

DreamStalker · Post by **DreamStalker** » Mon Jan 28, 2008 1:57 pm

allisonandrews wrote:Until Resmed comes out with Vista compatible software, I am stuck just using my LCD readout on my S8 Elite.

Last night's numbers:
Pressure - 8 (Titrated pressure = 9)
Leak - 0.0
AHI - 7.1
AI - 0.3
HI - 6.8

What do you think could cause my HI to be so high, yet my pressure stayed at 8? I know I was coughing a lot last night. Would this affect just the HI?

Have you been abducted recently or did the aliens mess around with your machine settings?

Without the software, it is not possible to know if the coughing has anything to do with the HI value. Why are you using 8 cm if you were titrated at 9?

krousseau is right, you would need additional pressure to kill off residual HIs.

bigk · Post by **bigk** » Mon Jan 28, 2008 2:28 pm

Being awake while the machine is running will definitely raise the HI. Make sure you remove the mask when you wake up.

If you were titrated at 9, I don't understand why they set the machine to 8. That would also mean a higher HI.

allisonandrews · Post by **allisonandrews** » Mon Jan 28, 2008 3:14 pm

Machine is set at 9. The pressure number is something about the average pressure 95% of the time, etc. I have the EPR set at 2, which brings pressure down to 7 when I exhale. Perhaps I will move it to 1 and see what happens to my numbers.

DreamStalker · Post by **DreamStalker** » Mon Jan 28, 2008 3:20 pm

allisonandrews wrote:Machine is set at 9. The pressure number is something about the average pressure 95% of the time, etc. I have the EPR set at 2, which brings pressure down to 7 when I exhale. Perhaps I will move it to 1 and see what happens to my numbers.

Well that explains it ... If you have EPR on it will indeed show a pressure less than what the pressure is set at (average of 7 and 9 is 8 ).

Make sure that the numbers you posted are the average representative of at least a week's worth of data before going and changing things up. If it is you might want to bump your pressure up by 1 cm and get another week's worth of data before determining what to do next.

Good luck!

krousseau · Post by **krousseau** » Mon Jan 28, 2008 4:01 pm

Whatever caused the coughing may be the cause of the higher HI. Or the coughing may have caused some reactivity/higher resistance in your airways. Whatever--as DreamStalker indicated--one night isn't enough to see any trends. Watch it for at least a week. And be aware of continued coughing (as if you wouldn't be) and the possibility you are developing a URI.

allisonandrews · Post by **allisonandrews** » Mon Jan 28, 2008 4:09 pm

Okay, thanks for the suggestions. This was just a one night thing. Actually, it's been the only night I have worn the mask in a few days and the first time to go all night in about a week. (Recovering from illness + Adjusting to a new mask + too much partying this weekend to think about it.)

Coughing is left over from illness - just some congestion issues that haven't left yet. I'm still coughing a bit in the daytime as well.

Country4ever · Post by **Country4ever** » Mon Jan 28, 2008 4:10 pm

I believe it was Slinky who said that her AHI improved when she didn't use as much EPR, so I think you could try that.

Would Allison's readout say 8 with EPR, when the CPAP is set to 9? I was under the impression that with CPAP, its ALWAYS that pressure. I didn't think it was capable of being any other pressure than what it was set at.??

billbolton · Post by **billbolton** » Mon Jan 28, 2008 4:15 pm

allisonandrews wrote:Sorry, no just straight CPAP set at 9.

Firstly, do you have EPR enabled? If not, the pressure data readout of 8 is curious, but if you do have EPR enabled its OK.

Secondly, the event scoring algorithm is based on autonomous sleep breathing behaviour, so if you are aware you are coughing during the night, you weren't asleep at that time, and that would definitely have some impact on the scoring results.

Anecdotally, there are scattered user reports that coughing can really confuse the scoring alogrithms on all flow generators that capture event data, but there's nothing much published on that.

Cheers,

Bill

billbolton · Post by **billbolton** » Mon Jan 28, 2008 4:26 pm

krousseau wrote:I think being awake while on the machine would make your numbers average out LOWER since you are less likely to have breathing events while awake.

No.

When awake we vary our breathing considerably, even if we are not particularly aware of doing so. The scoring flow generaors only have "flow" related information available to process in terms of determining what is or isn't an "event".

For concious breathing, the air flow can be quite different from autonomous sleep breathing, so quite normal concious breathing can readily be scored as anomolous events in sleep breathing terms.

Cheers,

Bill

allisonandrews · Post by **allisonandrews** » Mon Jan 28, 2008 9:11 pm

I just thought of something else. I remember while I was trying to get comfortable that I noticed it getting a bit harder to breathe. (Not by much, but just enough change that I noticed it). Turns out I was laying on the tubing or had it kinked in back on one side. I readjusted and everything was fine. I suppose that could have messed with my numbers as well.

I heard there was supposed to be Vista capable software coming out sometime this summer... guess I will just have to bide my time until then and hope I am still able to obtain it at that time...

track · Post by **track** » Mon Jan 28, 2008 9:46 pm

If you are talking ONE NIGHTS results I wouldn't give it a second thought. All sorts of reasons why one night can vary from the norm. The key is has the higher trend been consistent over at least a weeks time. If not don't give it a second thought. Perhaps you turned on your back more then normal or you got into a deeper sleep than normal or etc etc.

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High HI - what would cause this?

High HI - what would cause this?

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