" An optimal minimum IPAP-EPAP differential is 4 cm H2O"

[Shin Ryoku]

Hi all, new member here, recently self-diagnosed with OSA and finding my way with the help of great info from here and some of the other forums.


I was reading these guidelines: http://jcsm.aasm.org/articles/040210.pdf

And noticed that my current APAP settings of 15-20 cm H20 put me at a pressure level where consideration of a change to BPAP is recommended:

"If there are continued obstructive respiratory events at 15 cm H2 O of CPAP during the titration study, the patient may be switched to BPAP."


Furthermore, there is this comment regarding BPAP:

" An optimal minimum IPAP-EPAP differential is 4 cm H2O"


The level evidence provided for those recommendations has not been graded, nor has the evidence been summarized in any detail, so I am left wondering whether I should spring for a BPAP machine (I am doing this all out of pocket), and whether I would be better off with PS 4 than I am now with EPR 3.


Here is my data from last night as an example.  I feel great and have no residual OSA symptoms to speak of.




Those early in the night clusters of OAs seem common for me.  I'm guessing that they correlate with REM sleep.  

I have only been on CPAP for a few weeks total now and have been working on optimal gear and improving sleep hygiene as well as weight loss (the eternal struggle), so it's possible that my results will improve over time without further increasing my pressure settings.


I really don't mind buying a BPAP if there is a good reason to do so.  Fwiw, comfort has not been an issue for me.  I am very comfortable at the current settings.

[Walla Walla]

You don't need a BPAP. You have no need for a PS of 4 or more. The EPR you have now should be giving you plenty of exhale comfort.

I'd bump your Min pressure up 1cm though.

[Shin Ryoku]

Are the two recommendations I quoted based solely on achieving comfort, or is there some health benefit to having a higher PS when working with larger pressures? I have no asthma, COPD, or anything like that.

[Gideon]

Agree with Walla Walla.  Going to a PS of 4 with comfort is "proof" that a BiPAP/BiLevel machine is good for you because a CPAP machine cannot deliver that combination.  My BiPAP was covered fully by my insurance and my current machine was in early stages of failure (still good for a backup), and at the time I was throwing 11-15 AHI fairly consistently on a maxed out APAP.  I went with the BiPAP to have the capability of a higher pressure.  Again, you do not need that.

Another thing to keep in mind is that it is the EPAP (IPAP - EPR) that splints your airway for obstructive events.  To raise EPAP you can raise your IPAP thus the recommendation above.


edit
I'll add that a higher EPR, the lower the EPAP, lessening the airway splinting ability of your APAP.
CPAP settings are based on IPAP but BiPAP/BiLevel settings are based od EPAP pressures

Fred

[Sleeprider]

The findings you linked assume CPAP at single pressure, or EPAP equal to IPAP above 15 cm. You do reach those pressures, and frankly if your current minimum pressure was 18 with EPR 3 (18/15) you would be fully in-line with those suggestions and guidance. You currently reach pressures of 20/17, so I think you would definitely benefit from bilevel from both comfort and efficacy. Your current minimum pressure is 15/12 and Walla's suggestion to increase that pressure seems a reasonable short-term step. I think if you put minimum pressure at 17 (17/14), you would have an idea of why the 4 cm pressure is recommended as more comfortable at higher pressures. If these OA events are common for you, that might be worth a try.

I got my first BiPAP on Craigslist for $350, and it was a very low-hours PRS1 760. Since you are working out of pocket, a lightly used machine would give you an opportunity to decide if it is worth going all in on your next new machine.

[Walla Walla]

There is one thing about increasing pressure support. Sometimes the amount of pressure support you can increase by is also determined by your susceptibility to CA events. For example if I start going over 4 cm on my pressure support I start to pick up CA events. Of course this differs from person to person as many people go well above 4cm PS without a problem. Just something to keep in the back of your head.

[Shin Ryoku]

Is there any advantage of 18/14 to 18/15 besides improved comfort?

[Sleeprider]

Not necessarily. If you read the titration guidelines, the EPAP is used for control of OA and PS is used for hypopnea, flow limitation, snores and maybe RERA. Pressure support can increase tidal volume and minute vent which reduces carbon dioxide, however oxygenation is primarily a function of Positive End Expiratory Pressure (PEEP), and that is essentially the minimum EPAP. The bilevel has a great deal of flexibility in what it treats and comfort level, however as noted above, some people are sensitive to pressure support and respond to PS with central apnea. We have used

[ajack]

I can tell you my story.
honestly you aren't going to notice a difference between ps3 and ps 4 on a bpap, you will notice a difference between a cpap and bpap, because of the breathe shaping. Ti and rise time.

I was bouncing around 20 and found switching to a bpap was more comfortable. With your pressures, ( you only had a bad half hour) I would hire a Bpap for a month and see what you think. You can probably get a secondhand one for less than the price of the rental..It doesn't need to be auto, a manual will be fine. Just make sure it can use a SD card, so sleepyhead can give the data to adjust as you go.

[Shin Ryoku]

Your current minimum pressure is 15/12 and Walla's suggestion to increase that pressure seems a reasonable short-term step.  I think if you put minimum pressure at 17 (17/14), you would have an idea of why the 4 cm pressure is recommended as more comfortable at higher pressures.  If these OA events are common for you, that might be worth a try.

I went to 16/13 last night and had the results shown below.  Honestly, the pressure doesn't bother me in the slightest.  I don't even notice a difference from regular breathing.  Tonight I will try 17/14.