(08-23-2014, 10:30 PM)kfujioka Wrote: I thought the 12/7 means the air I breathe in is 12 and the pressure is only 7 when I exhale. So when I changed it to 10/5 it meant the air I breathe in is 10 and when I exhale it is 5. Is that right on a bipap machine? (I am very new to this.)
Hi kfujiokam welcome to the forum!
Yes, if you have a straight bi-level prescription your machine may be set to operate in BiLevel therapy mode, and you would be right about the prescription being always 12 for inhale and always 7 for exhale. And in BiLevel mode, changing IPAP to 10 and EPAP to 5 would mean always 10 for inhale and always 5 for exhale.
In bi-level machines, a name for the difference between EPAP and IPAP is Pressure Support (PS). So one could also describe your prescription by saying your EPAP setting is 7 and your PS setting is 5, and this would mean that your IPAP was 7 plus 5 (which adds to 12).
Actually, your PRS1 (Philips Respironics System One) BiPAP Auto machine has 3 therapy modes to choose from:
1. CPAP mode (one fixed pressure all night)
2. BiLevel mode (EPAP sets exhale pressure and IPAP sets inhale pressure)
3. AutoB mode (Auto BiLevel mode, which has settings for Min EPAP, Max EPAP, Min Pressure Support, Max Pressure Support, and Max IPAP)
In AutoB mode, the exhale pressure EPAP is slowly automatically adjusted by the machine, raising EPAP above its Min EPAP setting only as much as needed to avoid/reduce obstructive events such as obstructive apneas, hypopneas, Flow Limitation and snoring.
In AutoB mode, as the EPAP is slowly automatically adjusted higher or lower (always staying within the limits of Min EPAP and Max EPAP), the present inhale pressure (IPAP) is always the sum of the present exhale pressure (EPAP) plus the present amount of boost called Pressure Support (PS):
IPAP = EPAP + PS
In AutoB mode, Pressure Support is given a range (Min PS and Max PS) for how much the pressure can be boosted above EPAP during inhale. The machine will automatically (but very slowly) adjust PS within this range to further minimize obstructive Flow Limitation while allowing EPAP to stay as low as feasible.
In AutoB mode, the Max IPAP setting limits how high IPAP is allowed to go, so the Max IPAP setting should be set at least as high as the MAX EPAP setting plus the Min PS setting.
Obstructive Sleep Apneas is usually highly positional, with the worst position usually being when we are in the "supine" position (flat on our back). If you take precautions to stay off your back while you are asleep, the pressure needed to treat your obstructive sleep apnea will be lower.
You may want to ask your doctor to change your prescription to specify a range for EPAP and a range for PS, and the modified prescription might be much easier for you to fall asleep with.
For example, you could ask your doctor to consider prescribing:
Min EPAP: 5 or a little lower
Max EPAP: 7 or a little higher
Min PS: 3 or a little lower
Max PS: 5 or a little higher
Max IPAP: sum of Max EPAP plus Max PS
In any case, you might find it is more comfortable for you if you adjust the Bi-Flex setting to zero (off) or 1 or 2 or 3. Many patients find that the larger the setting for flex is, the easier it is to exhale.