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Increase in AHI with Oxygen, but feel better
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u2canbuild Offline

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Machine: ResMed Air-Curve 10 ASV
Mask Type: Nasal pillows
Mask Make & Model: Sept 1 Nasal Pillows Swift FX
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CPAP Pressure: 3-8
CPAP Software: SleepyHead Other Software

Other Comments: 4 months AHI = 0.2 !! Adding 1.5 to 2 Liter O2

Sex: Male
Location: Central Massachusetts, USA

Post: #1
Increase in AHI with Oxygen, but feel better
I usually use an oxyen concentrator in addition to my CPAP but notice that my AHI is about 30% higher when adding oxygen, However I almost always feel better in the morning with oxygen and my SPO2 is steadier and higher.

I spent 8 days in florida with my CPAP but no oxygen added, I had some ok days and some very tired and confused days........

Upon return to home yesterday and using my usual 1.5 to 2.0 L 02 ............I had an AHI 3 times my usual............ but woke feeling clear, no headache and had a great day.


Anyone else experience this?

Any ideas on what may be happening and or suggestions?
03-05-2015 09:21 PM
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eseedhouse Offline

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Machine: ResMed Airsense 10 Autoset
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Other Comments: Also on supplemental O2 at 3L/min. while sleeping.

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Location: Victoria, British Columbia

Post: #2
RE: Increase in AHI with Oxygen, but feel better
Interesting. I noticed no change in my AHI when the oxygen was added into the mix. I definitely started feeling better, though.

Ed Seedhouse
VA7SDH

I am neither a Doctor, nor any other kind of medical professional.

Actually you know, it is what it isn't.
03-05-2015 10:24 PM
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AshSF Online

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Post: #3
RE: Increase in AHI with Oxygen, but feel better
I am guessing most of the increase in AHI is central apnea events. It probably happens because you are taking more enriched air thus your end tidal CO2 is being lowered. If your end tidal Co2 is lower than usual, the brain may make your skip a breath or two to increase your co2 level.

It can be explained due to 2 things:
1) Higher pressure support. In your machine, the EPR feature is a pressure support of 1, 2 or 3 cm h20. More PS means more CO2 washout leading to central events.
2) More oxygen enrichment leading to more O2 and less CO2.

You should talk to your sleep doc/pulmonologist to see if your O2 enrichment level needs to be titrated. Although if you are feeling great and AHI is less than 5, it may be just nitpicking.

Started APAP 4-20, Closed range to 7.5-14, then straight 8.0 w/ Aflex 3
RDI always below 1. But sleep much much better at straight pressure.
Started on F10, Tried Quattro Air successfully. Finally settled on P10.
03-06-2015 12:05 AM
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PsychoMike Offline

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Other Comments: asthma, cyclist upgraditis, just a little crazy (honest :D )

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Location: Alberta, Canada

Post: #4
RE: Increase in AHI with Oxygen, but feel better
Probably wouldn't hurt to look at the type and duration of events. I'm like AshSF...I'd guess the centrals went up. I'd also think that the length of the events would be important.

If the events are relatively short (i.e. 10-12 s) there might be some fine tuning to do...if they are larger, it may mean a bit more work. If you need the supplemental 02 at night, then you may also need to look at a different style of machine (like an ASV) to deal with the centrals.
03-06-2015 02:38 PM
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vsheline Offline

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Machine: S9 VPAP Adapt (USA Model# 36007, not better 36037 or 36067)
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Other Comments: Marfan Syndrome, chronic bradycardia, occasional Cheyne-Stokes Respiration

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Post: #5
RE: Increase in AHI with Oxygen, but feel better
(03-05-2015 09:21 PM)u2canbuild Wrote:  Any ideas on what may be happening and or suggestions?

(03-06-2015 12:05 AM)AshSF Wrote:  It can be explained due to 2 things:
1) Higher pressure support. In your machine, the EPR feature is a pressure support of 1, 2 or 3 cm h20. More PS means more CO2 washout leading to central events.
2) More oxygen enrichment leading to more O2 and less CO2.

Hi u2canbuild,

Most patients find that their OSA is strongly positional. If your sleeping position away from home was mostly on your side and if at home you tend to spend more time sleeping on your back, this could explain the higher AHI at home, but only if the increase is from obstructive events rather than central apneas.


Hi AshSF,

Actually, studies have shown that adding O2 tends to reduce the frequency of central apneas, although not by much.

This kinda makes sense if you think about it from the following perspective.

When the air we are breathing is enriched with more O2, this increases the amount of O2 in our blood, so we are able to use more O2, which leads to more CO2 (used O2) in our blood, not less.

So I think it is a misunderstanding that supplementing with O2 will tend to lower our CO2.

Take care,
--- Vaughn

Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment. The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies - not on matters concerning treatment for Sleep Apnea. I think it is now too late to change the name of the group but I think Voting Member group would perhaps have been a more descriptive name for the group.
(This post was last modified: 03-07-2015 09:56 PM by vsheline.)
03-07-2015 03:44 AM
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AshSF Online

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Machine: PRS1 D560TS
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Mask Make & Model: ResMed P10, Bkup: Airfit F10 & Quattro Air
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Other Comments: Using APAP mode with fixed pressure

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Post: #6
RE: Increase in AHI with Oxygen, but feel better
(03-07-2015 03:44 AM)vsheline Wrote:  
(03-05-2015 09:21 PM)u2canbuild Wrote:  Any ideas on what may be happening and or suggestions?

(03-06-2015 12:05 AM)AshSF Wrote:  It can be explained due to 2 things:
1) Higher pressure support. In your machine, the EPR feature is a pressure support of 1, 2 or 3 cm h20. More PS means more CO2 washout leading to central events.
2) More oxygen enrichment leading to more O2 and less CO2.

Hi u2canbuild,

Most patients find that their OSA is strongly positional. If your sleeping position away from home was mostly on your side and if at home you tend to spend more time sleeping on your back, this could explain the higher AHI at home, but only if the increase is from obstructive events rather than central apneas.


Hi AshSF,

Actually, studies have shown that adding O2 tends to reduce the frequency of central apneas, although not by much.

This kinda makes sense if you think about it from the following point of view.

When the air we are breathing is enriched with more O2, this increases the amount of O2 in our blood, so we are able to use more O2, which leads to more CO2 (used O2) in our blood, not less.

So I think it is a misunderstanding that supplementing with O2 will tend to lower our CO2.

Take care,
--- Vaughn

Hi Vaughn: Thanks for the clarification.

Started APAP 4-20, Closed range to 7.5-14, then straight 8.0 w/ Aflex 3
RDI always below 1. But sleep much much better at straight pressure.
Started on F10, Tried Quattro Air successfully. Finally settled on P10.
03-07-2015 08:17 PM
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PsychoMike Offline

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Posts: 551
Joined: Aug 2013

Machine: ResMed S9 AutoSet
Mask Type: Other
Mask Make & Model: Varies with mood, ResMed F10 is my primary
Humidifier: ResMed H5i
CPAP Pressure: 12-17
CPAP Software: SleepyHead

Other Comments: asthma, cyclist upgraditis, just a little crazy (honest :D )

Sex: Male
Location: Alberta, Canada

Post: #7
RE: Increase in AHI with Oxygen, but feel better
Vaughn, I can't fault your logic for the average user. But I still wonder about the supplemental O2 that u2canbuild is on. If it is at all related to emphysema or COPD, it could be the issue.

For most folks, the level of CO2 drives their breathing and that production is fairly constant. For someone with a hypoxic drive, it is the level of O2 that drives the breathing...dropping O2 level vs. increasing CO2 levels like in normal folks. In that case, like in COPD, when you add supplemental oxygen, it decreases the breathing rate as the hypoxic drive isn't getting the same trigger...that would lead to more centrals.

I'm not doc, but I thought I'd float that one out there Wink
03-10-2015 01:07 PM
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