Is Mild Hypoxaemia incur from low APAP pressure ?

[ICEMAN]

Hi all , more so have just more a out of curiosity understandings? Questioning if say have No "Obstructive or Hypo Apneas' and only Central Apnea's, which I thought is with your brain just stopping the signal to breathe, then how does CPAP/APAP or even the other machines like is it BIAP ?  how do they treat the central ? as if getting CPR ?? as if its not as if any chest compressions ?



 Opp's  Please "KISS It "     Keep it Simple Stupid

[SarcasticDave94]

Central Apnea is going to be caused by a too low level of blood CO2. Sometimes a noob to PAP will get these CA as treatment emergent. This is signified as your likely due to flushing CO2 out faster than the body is used to, with it being a certain level.

If one had a majority of Central events in a diagnostic study the medicals should diagnose this as pre-existing CA and Titration for ASV should be ordered.

[Sleeprider]

Iceman, CPAP and bilevel machines without a backup rate cannot treat central apnea. The best device is an adaptive servo ventilator (ASV) which provides enough additional positive pressure during inspiration to fill the lungs in the absence of spontaneous effort. The algorithms of ASV differ between the manufacturers. Resmed (Aircurve 10 ASV) monitors the 3-minute moving minute vent and uses that as a ventilatory target, and Philips (Dreamstation Bipap Auto SV Advanced) targets teh 4-minute peak inspiratory flow. If you want to see more then here are a couple excellent resources for you to read that describe the machines and even how they differ:
http://www.masm.wildapricot.org/resource...Morgan.pdf
https://www.ncbi.nlm.nih.gov/pmc/article...mder-8-425

The problem is that in the U.S. Medicare an insurance companies make getting adanced PAP machines very difficult, and require patients to first fail CPAP and bilevel without backup rates. Even after that, there are a surprising number of doctors that don't understand ASV and prescribe ST (spontaneious timed) bilevel machines which do not have the variable pressure support, but operate on fixed pressures.

[SarcasticDave94]

Correct. Avoid the ST if at all possible. I didn't have to jump through that one to get ASV, but it was a tough long hard road from CPAP to ASV as it was.

[ICEMAN]

Central Apnea is going to be caused by a too low level of blood CO2. Sometimes a noob to PAP will get these CA as treatment emergent. This is signified as your likely due to flushing CO2 out faster than the body is used to, with it being a certain level.

If one had a majority of Central events in a diagnostic study the medicals should diagnose this as pre-existing CA and Titration for ASV should be ordered.

Thanks for reply Dave94, if you don't mind to more clarify?  Have I mixed up my understanding, or misinterpreting re your post. 

The last weeks I purposely reducing my APAP pressure's both  Min & Max pressure,  in a endeavor of my thinking to lowering my overall APAP pressure of Oxygen O2, as thinking that my present treatment may be oversupplying of O2 Oxygen? and may be contributing to high AHI of CA or Central's ?

So is your post is virtually saying the same thing? just worded different ? and still relates to having too much O2, which dose it then contributes to low level of Co2 Carbon-Dioxide, which causes a trigger to the brain to Stop breathing, due to the excess of  Oxygen O2 or thus alternative I presume is too low CO2?  

In addition for the above I purposely haven't Don't used comfort setting EPR, but may intend try using but without then increasing the APAP pressure ?



https://myapnea.org/forum/not-understand-epr-setting  
EPR works like low level BiPAP. As you breathe in the pressure increases and as you breathe out it decreases, which means that more air is moving in and out of your lungs than normal - the EPR is slightly augmenting your respiratory effort. This may sound all well and good, but there is a reason that you breathe the amount you do. Too little is a problem, we all know that, but too much can be a problem too. The extra breathing work done by EPR can be enough to hyperventilate you, sending your CO2 level too low which, in turn, causes central events.

[SevereApnea]

Iceman

I like to separate out pO2 (Oxygen) levels and CO2 (Carbon Dioxide) levels in my thinking.

The primary driver for respiration is high Carbon Dioxide (CO2) levels.

I did this when I first got my Oximeter attached to the CPAP machine:

I tried to hold my breath for as long as I could. At some point I *had* to breathe. My pO2 remained well above 91% (normal): the fact that I *had* to breathe means that my CO2 levels were climbing.

I did the same thing by breath-holding sequentially over many of minutes, my Oxygen stayed fine. But at some point I could not longer carry on, because high CO2 levels forced me to breath.

My main aim with CPAP at the moment is to still have some CA.
This means my CO2 is not too high. 
If I experience headache, palpitations, feel sweaty when I wake up and I see had Zero CA I can assume that either my CO2 was normal or was too high.

I feel better on waking up if I have some events, both OSA and CA.

Also, what I found by trying to reduce my pressures to silly low levels (below my titrated pressures) is that I would experience what is called air starvation.
At that point I *have* to remove the mask (what I call the GT*MO moment = Get The Mask Off). I then have to spend some time (even hours) playing catch-up breathing before I can go back to sleep. I have no proof, but suspect this is due to high CO2 levels, and having to breathe this off.

I have stopped using my pulse oximeter while sleeping, because I found my O2 levels were always 92 - 98% while sleeping and did not correlate with feeling bad the next day.

If I have slept too long with pressures that are marginally low, then although I don't get to the point of GT*MO, I will have a bad headache all day and experience what I call Air Hunger: having to take long deep breathes for hours and hours, blowing off CO2 and correcting pH levels.

I am learning to not worry too much about the "science" behind all this: just what makes me feel good or bad when I wake up.

In other words: you can't really have too high Oxygen levels unless you are on supplemental Oxygen treatment. But you can have too high CO2 levels if your CPAP pressures are not optimal.

Hope this helps.

[SarcasticDave94]

Yes don't consider oxygen level in a cause for CA discussion. It's strictly CO2 levels that's involved.

Since you don't have EPR involved, maybe lowering Max pressure may affect CA some, but I'd not think the Min pressure needs edited or you'll bring back Obstructive events.

[ICEMAN]

Thanks SevereApnea & Dave for your response, knowledge, comments. I previously thought that APAP pressure could be often contributing factor, and then incur the Brain telling to stop breathing as is taking in to much O2, so previous understanding some truth but bit to simplicity?  is it,  but i think slowly getting my head around it for layman! 

https://www.sleephealthfoundation.org.au/central-sleep-apnea.html
What causes Central Sleep Apnea?
The brain may be slow to respond to changes in oxygen and carbon dioxide levels in the blood when breathing slows down. This may occur in people who have had sleep apnea for a long time. This is due to blunting of the breathing reflex. CSA may also be due to a slow circulation from heart failure having an effect on the normal breathing reflex pathway. This causes a pattern of over-breathing and then under-breathing (periodic breathing) or stopping breathing. Other causes of this pattern of CSA include some drugs (e.g. narcotics such as morphine) or having cerebrovascular disease (e.g. a stroke). These affect the breathing control centres in the brain.
CSA can also be due to weakness of the muscles that make the lungs expand and contract, such as in neuromuscular disorders like polio. It can be also be caused by an abnormality in the shape of the chest wall or the lungs being too stiff. This can lead to under breathing, called hypoventilation. CSA can disturb your sleep. It can also make your body retain carbon dioxide. This can lead to morning headaches or confusion.

https://www.sleepapnea.org/untreated-sleep-apnea-and-stroke-stroke-awareness-month/
Central sleep apnea (CSA)

This form of sleep apnea is far less common but no less dangerous. It is caused by a misfiring of signals between the brain and breathing apparatus as one sleeps.
The person with CSA may lie there, not breathing as they sleep, making zero effort to breathe, until the brain notices increases in carbon dioxide in the bloodstream (which collect when there a lapse in exhalation). Then the brain signals the body to reawaken through the release of stress hormones so that breathing can be restarted consciously.
People with CSA may also gasp for air after long periods of not breathing and will experience problems with insomnia, broken sleep, nightmares, daytime fatigue, and hypertension as well.

[ICEMAN]

Yes don't consider oxygen level in a cause for CA discussion. It's strictly CO2 levels that's involved.

Since you don't have EPR involved, maybe lowering Max pressure may affect CA some, but I'd not think the Min pressure needs edited or you'll bring back Obstructive events.

Oh yes Dave that part I did understand, my intention of lowering pressure with curiosity if would lower my CA but to obviously intended to monitor in a balance to not also impact other events.

A also thoughts and maybe more so early days of CAPA " Brick's" and and bit less controlled since APAP ? as in concern Apnea's changing own pressure "especially increasing pressure" and DR's "or some "  frowning on Apneas taking some control knowledge management of own Sleep health, with Ability/ Capability.