New BiPAP, still having long periods of low oxygen

[phlamingo]

Hi all,

I started using a CPAP a year ago after years of having untreated OSA. When I started having severe fatigue last fall but didn't receive any help from doctors, I bought an overnight oximeter in hopes of learning something useful. What I learned is that during about half of my nights, my oxygen drops below 88% for a solid 30 to 45 minutes. My sleep doctor was not concerned, nor did she think it was causing my fatigue. (Recently received a diagnosis of ME/CFS - Chronic Fatigue Syndrome which explains that) Based on this group's helpful suggestions, I went to a new doctor (but I don't like her, either). She reluctantly agreed to order another sleep study to evaluate need for a BiPap and supplemental oxygen. That was in June, and I started using a ResMed AirCurve 10 VAuto a month ago with oxygen bleed-in at 1 liter/min.

I really like the BiPAP - I don't feel like I'm struggling for air like I did before (with the AirSense 10 AutoSet, 16 to 20 cm) and my avg. AHI is 0.35. But I don't think the BiPAP or the added oxygen are helping with my low oxygen. Below are screenshots from last night which was my worst low oxygen night yet (avg 89%, 92 minutes under 88%, min 79%).

Thoughts? Should I be going to a different specialist, since this does not seem to be related to sleep apnea?

Thanks!

   
   
   

[Sleeprider]

The BiPAP is doing its job, but your low oxygen is not being helped by such a low oxygen feed rate. That 1-L/min might work with a cannula, but certainly not with a CPAP or BPAP at your pressures. I wrote a wiki you should look at http://www.apneaboard.com/wiki/index.php..._with_CPAP The point of an oxygen bleed is to increase the fraction of inspired oxygen (FiO2%), but when applied through a positive pressure device, you have to account for the very high dilution of air flowing through the PAP to prevent rebreathing of expired air. In your case, with pressure 14/8 and a full face mask, the VPAP is flowing approximately 40 L/min of dilution air mixed with your 1-L/min of oxygen That is not going to get much increase of FiO2.

Ambient air contains 21% oxygen and without any supplemental oxygen, we generally breathe a FiO2 of 21%. People with oxygen deficiencies need to be titratated to determine their FiO2 requirement to maintain a satisfactory SpO2, although trial and error is also a titration method. We don't know what that target is for you, but it may be anywhere from 30-60%. We could then calculate what feed-rate of oxygen would be required to meet your FiO2 with BPAP at the pressure and mask type you are using. This actually takes someone who understands oxygen bleeds and gases, and given your oxygen prescription, I'd say you don't have that person working for you.