[CPAP] New user, looking for tuning advice

[JoeyWallaby]

At this point my overall goal is to stay with a stable, and comfort-driven set of machine settings, and focus on mask experimentation and selection for now.  My biggest question as to what's actually happening in my sleep is whether the CA's are therapy-induced or are happening independent of therapy.

Maybe using EPR to see if CAs increase?

[wkf94025]

@Joey, most nights I have EPR on, at 3cm.  What is the general correlation between EPR and CA's?  More EPR = less CA, or vice versa?

[JoeyWallaby]

The theory is EPR causes increased respiratory efficiency, which in some people, causes CO2 washout (hypocapnia) that reduces respiratory drive, thus inducing CAs.

[Gideon]

Fortunately that is only the "Lucky Few"

[wkf94025]

The theory is EPR causes increased respiratory efficiency, which in some people, causes CO2 washout (hypocapnia) that reduces respiratory drive, thus inducing CAs

Very helpful.  And just to clarify, under this dynamic, the higher the EPR setting (e.g., 3cm) the more likely a CA?  Or is the theory that ANY EPR is likely to lead to induced CAs?

Fortunately that is only the "Lucky Few"

I don't understand that at all.

[jaswilliams]

Higher EPR = More CA’s if your susceptible to it, often fixed pressure and no EPR reduces CA’s for these people. It had no impact on my CA’s so an ASV was needed

[JoeyWallaby]

Only some people are effected. Dose (EPR level)/response (hypocapnia-induced CAs) curve depends on the person.

[Gideon]

Here is the theory.
A primary driver for breathing is pCO2 in the blood as sensed by Chemoreceptors.  many other signals are present but none others have a significant impact on reducing the drive to breathe.  When the pCO2 is 'high' this signals to take a breath.  When low this signal fails to fire thus causing a central apnea.  Not breathing the pCO2 builds back up and after an apneic period, a breath occurs.


It is the sensitivity to this parameter that actually determines who will actually suffer from central apnea.

A PAP machine almost always improves the efficiency of breathing, look at the increases in minute vent and tidal volume, especially with PS or EPR, and with this improvement oxygen, and CO2 exchange is improved with more Oxygen in the blood and too much CO2 washed out of the system..  Except in this case is not a bad thing. 

Traditional treatment here has been to reduce pressure variance and then decrease pressure to reduce central apnea which is accomplished by reducing the washout of CO2 with the reduction of PS / EPR.  Tradition treatment from the medical community has often, not always, been to throw a higher level machine at the patient which almost always fails. 

Obviously this only works with 'CO2 induced Central Apnea" which is most often called Treatment-Emergent Central Apnea.

EERS come to play as it is a method to somewhat elevate the pCO2 in the blood keeping the level above the threshold for causing an apneic event.

[wkf94025]

Thank you all for rapid and expert responses. So since my sleep study showed zero CA's, and a mix of 2/3 OA's and 1/3 H's totaling ~10 per hour without therapy, if initial therapy (4cm-20cm and EPR=3) eliminated virtually all OA's and H's, but CA's are now the predominant event type (AHI ranging from 2 to 10, averaging 3.7), does it seem I am one of those susceptible to therapy-induced CA's? If so, I am thinking my next settings should be raising min pressure a bit (5cm initially, then small steps upward), and turning EPR low/off. If exhale feels forced/uncomfortable, then gradually bring EPR back on. If CA's reduce or disappear with EPR low/off, and reappear as EPR is added, then I think that would confirm my CA's are therapy induced, and I want little if any EPR.

Correction or confirmation welcome.

[jaswilliams]

Increasing pressure wont do any thing for CA’s but a more suitable min pressure is 6 with an EPR of 2 you don’t have enough CA’s to worry about and will likely diminish over time as you get used to using your machine.