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RE: SPO2 drops to 89% when lying down.. - tiredmonkey - 11-14-2017
Basically you inhale air with 21% oxygen (O2) , your lungs puts it in your blood stream and goes to your heart, your heart pumps oxygen rich blood to all your tissues via arterial system.. you then burn that oxygen and produce carbon dioxide (CO2) as a by-product (think like exhaust fumes as a by-product of combustion in your car).. that CO2 needs to come out because its toxic to you, so it goes from the tissues into the venus (oxyen poor) blood stream and back to the heart which pumps it back to your lungs so you can breathe it out..
So - the idea is that if you have slow long deep breathes, you maximize the amount of CO2 that can be diffused into your lungs and can be expelled and maximize the time for he O2 to be diffused back into the lungs so have decent amount of O2 to take back to your tissues..
The premise of high pressure supplied by a PAP machine on inhalation allows you to draw maximum amount of air coming in (O2) and clear obstructions.. then if you drop the pressure on exhalation, you can minimize the exhalation effort and maximize the amount of air you breathe out, thus also getting rid of as much CO2 as you can..
if you breathe really shallow (hypoventilation) you dont expell enough CO2 and you dont uptake enough O2 so you get double whammy of not enough O2 levels and high CO2 levels in your arterial blood that goes to your tissues., both of which is not good.. you starve your tissues of oxygen and you increase your CO2 toxicity levels.. shallow breathing is bad, but not breathing due to obstruction or otherwise radically and exponentially makes this worse..
There is a much more technical explanation of diffusion of the partial pressures of gasses into and out of a medium to reach equilibrium and how O2 / CO2 gas exchange works in lungs, blood, tissues, etc.. but thats waaaay too much information
RE: SPO2 drops to 89% when lying down.. - trish6hundred - 11-14-2017
Hi tiredmonkey,
WELCOME! to the forum.!
Good luck with CPAP therapy.
RE: SPO2 drops to 89% when lying down.. - tiredmonkey - 11-14-2017
RE: SPO2 drops to 89% when lying down.. - Sleep2Snore - 11-14-2017
Yes, the only thing is you have to get the O2 past your throat and into your lungs first, so you need a CPAP or something else to keep your throat open or the tongue out of the back of your neck and you should be fine. Unless you shallow breath a lot or stop breathing for periods of time (some people do) central apnea, this is not fully understood. It is when your airway is clear but you do not breath.
I used to do this and then wake up with a jump, heart pounding like a jack hammer
screaming for breath. 
Good luck with your CPAP treatment.
RE: SPO2 drops to 89% when lying down.. - Sleeprider - 11-14-2017
(11-14-2017, 12:31 PM)tiredmonkey Wrote: Thanks!!
Thats exactly why it has me pondering.. im 5-11 and 170lb.. so not super scrawny, but not obese by a long shot..
Just weird that its only when horizontal it dips..
During apnea, the CPAP does not produce a backup breath and stays at it's set pressure. In the case of Resmed it is at EPAP pressure based on CPAP pressure minus EPR. Philips machines are always at CPAP pressure except during the transition from inhale to exhale. With complex apnea, you probably need adaptive servo ventilation (Resmed Aircurve 10 ASV or Philips Dreamstation Auto SV Advanced). What is your AHI?
RE: SPO2 drops to 89% when lying down.. - Sleeprider - 11-14-2017
(11-14-2017, 01:24 PM)Walla Walla Wrote: jerry1967,
I'm not an expert on it. I believe the idea is to allow a large gap between the inhale and exhale to make it easier to exhale the air. That allows a larger exchange of O2 for CO2.
If I'm wrong somebody please correct me.
Based on fundamental ventilation principles, EPAP or Positive End Expiratory Pressure (PEEP), is primarily responsible for oxygenation, and pressure support improves minute vent and reduces CO2.
When we talk about complex apnea, those two approaches can be at odds, because both pressure and pressure support can increase central apnea. The fundamental problem being CPAP and BiPAP without backup rate are good for treating obstructive apnea, but are not generally effective in complex and central apnea. Simple bilevel can indeed improve ventilation volume, but can cause centrals in those prone to that problem.
RE: SPO2 drops to 89% when lying down.. - tiredmonkey - 11-14-2017
(11-14-2017, 08:21 PM)Sleeprider Wrote:(11-14-2017, 12:31 PM)tiredmonkey Wrote: Thanks!!
Thats exactly why it has me pondering.. im 5-11 and 170lb.. so not super scrawny, but not obese by a long shot..
Just weird that its only when horizontal it dips..
During apnea, the CPAP does not produce a backup breath and stays at it's set pressure. In the case of Resmed it is at EPAP pressure based on CPAP pressure minus EPR. Philips machines are always at CPAP pressure except during the transition from inhale to exhale. With complex apnea, you probably need adaptive servo ventilation (Resmed Aircurve 10 ASV or Philips Dreamstation Auto SV Advanced). What is your AHI?
So from my understanding, the Philips does this "pressure pulse" to check if it is Clear Airway or Obstructive Apnea, but you'r right, I dont think it does anything beyond reporting it (i.e. it doesnt increase pressure to force a breath)..
My apneas are mostly CA with only a few OA events.. I have quite a few more Hypopneas though..
I've Only started treatment a week ago and AHI is kind of still of all over the place jumps around between 3 and 7 with majority being Hypo.. And ontop of it all, I got a cold the weekend and I could not use it with my nasal mask.
My puzzlement really just came from this weird SPO2 drop when lying down in general.. not when sleeping with CPAP, just in general when lying horizontal and watching TV without mask, it does that.. my breathing is normal while lying down, I think..
RE: SPO2 drops to 89% when lying down.. - tylereckert - 01-04-2018
Quick question Jerry, did you ever find a solution to your oxygen levels falling while lying down? My levels are doing the same. They are 95-98 while standing or sitting upright, but are 88-92 while reclining or lying down. No doctors have yet been able to find a reason for this and it is beginning to concern me. Thanks.
RE: SPO2 drops to 89% when lying down.. - tiredmonkey - 01-04-2018
Nope - no idea.. still happens.. when I am on my back, wide awake, breathing normally, it drops to 87%
I dont feel out of breath my heart rate is down to about 57-60 and im relaxed breathing normally..
So - NO idea.... I even bought another different brand oximetry meter just in case mine was reading wrong.. but they both read the same..
RE: SPO2 drops to 89% when lying down.. - stanleydean - 01-04-2018
Hi tiredmonkey,
This is an interesting discussion. The thing I'm wondering is what is your O2 level doing when you are sleeping with your CPAP. I didn't get whether you were using a recording oximeter that can be used while sleeping or a one shot meter. If what you are reporting takes place while awake and without CPAP then there is something else going on that should be checked out by your doctor and maybe by a pulmonoligist. But it would be good to know what's happening while sleeping, both with and without CPAP. My pulmonoligist sent me home with a recording oximeter, he calls it a "poor man's sleep study". And also, as soon as you can, post some SleepyHead data.
Good luck and keep us posted,
Stan