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Low SpO2 Levels when using Bi-Pap Machine
My wife has COPD and uses a bi-pap machine at night. She recently bought a oximeter watch with an audible alarm. She set the alarm @ 84 SpO2 and the alarm goes off 4-5 times an hour. She uses a full face mask and has the O2 set on 4 Liters.

If she takes the bi-pap machine off and just uses her nasal cannula and sets the O2 on her usual 3 Liters then she is able to sleep through the night with no alarms. The O2 level never drops below 84.

What causes a bi-pap machine to cut the oxygen off?

She has had the bi-pap tested by two separate companies and they say it is functioning properly. They gave advice to raise the ipap/epap to 24/19 and use 5 L of O2 but this does not seem to have any impact except to give her a tremendous headache. Levels continuously drop below 84 and down into the mid-70's

Any advice appreciated. Her pulmonologist suggested the 24/19 after a recent sleep study and offers no advice. Says she has a lung disease and learn to live with it.
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Here's a wild guess. The O2 is being introduced into the CPAP flow. The CPAP pressure is rather high, so the mask vents considerable flow.
In essence venting a large percentage of the added O2 to atmosphere.

I'm don't think sleeping with only the cannula is a good idea.

Perhaps a second medical opinion should be sought?

This is out of the realm of questions received about CPAP. It's truly a job for a doctor or other medical professional.

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JustMongo passed away in August 2017
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Maybe the hypoxia's are due to central apnoeas induced by the BiPap?
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The bi-pap machine has a "gadget" connected to the output flow with a swivel on it. I connect the oxygen tubing to the swivel on the gadget and the bi-pap hose to the other end. In essence the bi-pap ...a spacer with oxygen swivel ...mask hose. I don't know any other way to connect the oxygen.
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Hi carlechols,
WELCOME! to the forum.!
Hang in there for more answers to your questions.
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(04-13-2016, 04:37 PM)Carbon Wrote: Maybe the hypoxia's are due to central apnoeas induced by the BiPap?

That would be easy enough to find out.

The real question is the purpose of the bipap machine. If it's being used to treat obstructive sleep apnea it seems it would be needed to keep the oxygen level above 84. On the other hand, if the apneas and hypopneas cause enough repeated arousals I suppose it could keep the oxygen level above 84. It would ruin the night's sleep though, and you'd experience symptoms from that that not only ruin the quality of your life, they can lead to an early death or a stroke.
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(04-13-2016, 04:37 PM)Carbon Wrote: Maybe the hypoxia's are due to central apnoeas induced by the BiPap?

How many CAs is she having and how long are they???

I think you need a new doctor.
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I also think you should get another opinion. My family member doesn't need his bipap at all if he has oxygen fed by canula. Seems to me her overall quality of life is superior with oxygen only.
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Okay BiLevel and COPD here, no O2.
I had headaches and was told that I was retaining CO2. I did not have to change the therapy pressures to "fix" this
I use a Resmed machine, so I can only talk about my personal machine.
I was mainly hypopnea with a few OA and more centrals, the machine removed all the hypopneas and 90% of the OA.
now for the breathing and comfort stuff.
again I don't know what these things are called on your wife's machine or what features are available, I am guessing that there is something similar.

On Resmed there is a inhale time setting and a trigger level. There is a chart on how to set these for COPD users. BUT for me that was the exact opposite of what I needed.

There is a bar on the screen that shows pressure during my breathing, starts at min and goes to max and then drops back quickly. I could sit there and watch the bar progress and it would drop off BEFORE I had stopped inhaling. On the Resmed this is the TiMax setting, what is the maximum time the machine will let you inhale. Default was 2.0 seconds. I changed it to 3.0 seconds and it "seemed" fine. Then After no improvement overnight I looked at sleephead and noticed that my breathing slowed down overnight. adjusted to 3.4 and it was much better. Recently I changed to 3.7 seconds and am oh so much better. I also changed my trigger to high sensitivity to make sure it caught even slight inhales.

COPD and sleep apnea are two different things and both need to be treated. I do not suggest that your wife stops using CPAP because of her COPD and quality of life. Tune up the therapy so she can treat both. My DME and Sleep Doctor were of zero help in doing this. Doctor finally said that I had his permission to change any and all setting on my own, he had given up.

Don't give up, test different settings and my guess is that as long as the apneas are behaving, then you don't need to change therapy settings to get things sorted out.

Oh and running more O2 into the mask does not make your wife inhale it or help her to expel the CO2.
Keep posting with progress.
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(04-14-2016, 12:44 PM)PoolQ Wrote: On the Resmed this is the TiMax setting, what is the maximum time the machine will let you inhale.

Permit me to rephrase that. TiMax is the maximum time the machine will stay at IPAP pressure; not the maximum time it will let you inhale. The machine may switch from IPAP to EPAP pressure; but you may still be inhaling.

Now, let me add a caution to changing default timing parameters -- these parameters are best left at default. Anyone who wants to tweak them needs to fully understand what these parameters do; and that they do so at their own risk.

What worked for PoolQ is not a solution for everyone with COPD.

Admin Note:
JustMongo passed away in August 2017
Click HERE to read his Memorial Thread

~ Rest in Peace ~
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