I understand that IPAP is the higher level of a bi-level machine.  That EPAP, and CPAP are the same numbers, that EPAP is on bi-level machines.

My sleep Dr. told me that the higher level was the CPAP and that the lower EPAP level did not matter because your airway did not obstruct during exhalation. What is the truth???


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CPAP only has one pressure and has no relation to IPAP/EPAP except as a starting point during titration. BiPAP has 2- IPAP on inhale which is higher and EPAP on exhale which is lower. I'm on BiPAP ST for CSA but have read a lot on BiPAP use for OSA and my understanding is that they titrate IPAP to eliminate apnea and EPAP to eliminate hyponeas. Here is a titration guideline for OSA  that might help: http://www.ent.health.ufl.edu/Forms/cpap2000.pdf

Hi Guys!
Actually, I do believe that it is the other way around, you have to fix the apneas with the EPAP, or baseline pressure, first.  If the airway is not open, then increasing the IPAP would not help address an apnea, because the machine could not sense an inspiratory effort and respond.  But as long as there is any kind of flow, as you see in a hypopnea, then you can blast through it with the IPAP.
Haku, while the explanation offered by your physician that obstruction does not occur during exhalation is basically correct (this is what allows C-Flex to work), proper EPAP setting is critical in OSA treatment.  If the EPAP setting does not completely eliminate apneas (not necessarily hypopneas, RERAs, snores, etc.) BiPAP simply will not work.  It will simply sit there waiting for an effort that it cannot see.
So in your case, if your ideal CPAP was 14 cmH20, you could only use BiPAP of 14/7 if all your apneas were gone at 7.  If it took 14 cmH2O to get rid of all your apneas, then your BiPAP would have to be at least 16/14.  Since you had mostly hypopneas, chances are that your EPAP setting is functional.  The point is, though, EPAP selection is not arbitrary, it's based on the point where apneas are eliminated, or at least turned into hypopneas.
sleepydave

Sorry for the dumb question but what is a hypopneas?


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Hi Haku!
The definition of a hypopnea varies a bit, but generally, it's a 50-80% reduction in breathing, with a desaturation and/or an arousal.  There is at least some movement, so the BiPAP will be able to pick up effort and respond.
BTW, I agree with Christine that CPAP and EPAP are not the same thing, but in explaining the differences of CPAP and BiPAP to patients, I will often asssociate them very closely, as in:
"You are sitting here now breathing with no support, a supplemental pressure of 0.  We are going to add pressure to your airway to inflate and support the unstable airway, for example, to 5 cmH2O.  In both CPAP and BiPAP, this becomes your baseline pressure.  In BiPAP, however, when you inhale, the machine will give you additional support, adding some extra presssure.  This gives you a second level of pressure.  The first level, CPAP, becomes EPAP, and the second level is called IPAP.  Two levels of support, ergo, Bi-Level."
Sometimes offering the explanation in this way makes it a little more clear.
sleepydave