(06-21-2014 04:35 PM)jcarerra Wrote: So here is the question...
1. can someone briefly explain the major differences/functions of
a. Auto (Resmed Autoset an example)
b. Bi-Level (same as BiPAP?)
c. Bi-Level Auto
Auto PAPs have one pressure level that varies from the min pressure setting
and max pressure setting
in response to OAs, Hs, snoring and flow limitations. APAPs are billed under the same insurance code as plain old CPAPs are both billed under the same HCPC code, namely E0601. APAPs and CPAPs are both prescribed for plain vanilla OSA.
Bi-level machines include the Resmed S9 VPAP S and the PR System One BiPAP Pro. These machines have two distinct therapeutic pressure settings. The IPAP pressure is the pressure delivered during the inhalations. The EPAP pressure is the pressure delivered during the exhalations. The difference between the IPAP and EPAP is typically around 4-5 cm, but it can be as little as 1 cm or as much as 8-10cm (or more).
NOTE about Resmed Machines: If the PS = 0, 1, 2, or 3, a Resmed S9 VPAP S will act and behave very similarly to an S9 Elite with the EPR set to 0, 1, 2, or 3 respectively. There's a small (but potentially significant) difference in how the pressure is raised back up for the inhalations, however. The Elite will start raising the pressure just before the inhalation starts (at the very tail end of the exhalation), whereas the VPAP S will wait until it is sure the inhalation has started. Most people cannot feel this difference. So the major difference between an S9 Elite and a bi-level machine is that the difference between IPAP and EPAP can be greater than 3 cm.
Bi-level auto machines are like bi-levels in that they deliver a distinctly different pressure on inhale (IPAP) and on exhale (EPAP). But the IPAP and EPAP pressures are allowed to vary during the night in response to OAs, Hs, snoring, and flow limitations. The difference between IPAP and EPAP is called the pressure support
or PS for short. Exactly how the IPAP and EPAP pressures vary depends on both the brand of bi-level used and the PS setting(s).
On a Resmed S9 VPAP Auto, there are three critical therapeutic settings:
The S9 VPAP Auto increases/decreases the EPAP and IPAP at the same time all night long, and the PS setting is simply how far apart the two pressure levels are. In other words:
min IPAP = min EPAP + PS
max EPAP = max IPAP - PS
And all night long, the EPAP is allowed to range from min EPAP
to max IPAP - PS
and the IPAP is allowed to range from min EPAP + PS
to max IPAP
. At all points during the night IPAP - EPAP = PS.
On a PR System One BiPAP Auto, things work a bit differently. The IPAP and EPAP are allowed to vary independently of each other. This requires four therapeutic settings:
The minimum IPAP = min EPAP + min PS and the maximum EPAP = max IPAP - min PS. EPAP (but not IPAP) is increased for clusters of OAs and snoring. IPAP (but not EPAP) is increased for clusters of Hs, RERAs, and flow limitations. In other words, the IPAP and EPAP are allowed to vary independent of each other as long as
min PS < IPAP - EPAP < max PS
In other words, the difference between IPAP and EPAP must stay between the min PS
and max PS
settings. So if IPAP - EPAP = min PS
needs to be increased, both IPAP and EPAP will be increased. Likewise, if IPAP - EPAP = max PS
needs to be increased, both IPAP and EPAP will be increased.
NOTE 1: By setting min PS = max PS
on a PR System One BiPAP Auto, you can make the BiPAP Auto behave very similarly to the Resmed S9 VPAP Auto. There is no way to make a Resmed S9 VPAP Auto behave like a System One BiPAP when min PS
and max PS
are different numbers.
NOTE 2 about Resmed Machines: If the PS = 0, 1, 2, or 3, a Resmed S9 VPAP Auto will act and behave very similarly to an S9 AutoSet with the EPR set to 0, 1, 2, or 3 respectively. There's a small (but potentially significant) difference in how the pressure is raised back up for the inhalations, however. The AutoSet will start raising the pressure just before the inhalation starts (at the very tail end of the exhalation), whereas the VPAP Auto will wait until it is sure the inhalation has started. Most people cannot feel this difference. So the major difference between an S9 AutoSet and a bi-level auto machine is that the difference between IPAP and EPAP can be greater than 3 cm.
Quote:and when does one need a. vs b. vs c.?
A script that specifies "CPAP at n
cm" can be filled by any E0601 machine, although a DME that is willing to sell an APAP will set the APAP up in straight CPAP mode.
Bi-level and bi-level auto machines are both billed under the HCPC billing code E0470. A script that reads "CPAP at n
cm" or "APAP min
cm" is NOT enough for a DME to legally sell you a bi-levle or bi-level auto machine.
Both E0601 machines and E0470 machines are used to treat plain vanilla OSA. E0470 machines, however, are usually prescribed only when the patient is having certain kinds of difficulties with PAP therapy.
E0470 (Bi-level and bi-level auto) machines are typically prescribed for one of the following reasons:
- Patient has failed to respond to CPAP/APAP for some reason, but moving the patient to an even more expensive ST or ASV machine is not (yet) medically warranted. In other words, the patient's AHI has not yet come down to the normal range, but it's not clear the problem is CompSA. Among other things, the bi-levels can deliver up to 25 cm of pressure, whereas APAPs can only deliver up to 20 cm of pressure.
- Patient is unable to tolerate CPAP/APAP for some reason, and there is reason to believe the switch to bi-level may help. Typical "can't tolerate" reasons are severe aerophagia at pressures required to keep the OSA under control and inability to exhale against the pressure comfortably even though exhale relief is set at its maximum.
- Patient needs at least 15cm of pressure to contol the OSA in an in lab titration study and the tech has reason to believe the high pressure is causing additional sleep disturbances. Techs can switch to a bi-level titration in this case, and if the patient does better on bi-level, then bi-level may be the first machine recommended.
- Patient has central sleep apnea or complex sleep apnea, but the insurance company first requires the patient to try (and "fail") CPAP/APAP/Bi-level before the insurance company is willing to authorize a more expensive ST or ASV machine. The rationale is not quite as cruel as it sounds: Some people with CompSA don't need the full support that an ST or ASV machine provides---i.e. after using an appropriately set bi-level for several weeks, the problems with centrals resolve themselves and the person does fine on bi-level.
Quote:2. Also, My mind cannot see the difference in bi-level as opposed to the exhale pressure reduction function that is an "added" feature in many models.
It's a matter of degree. If you are using a bilevel with a PS setting of 1,2, or 3 cm, then it can be argued that a Resmed S9 AutoSet should do the job. However, I can attest that I'm that rare patient where the S9 AutoSet was not the best choice even though my typical PS on my BiPAP Auto is often right around 3cm.
In my case, the Resmed S9 AutoSet (with EPR = 3) triggered severe aerophagia when I first started in CPAP mode with my (original) titrated pressure of 9cm. (So effectively I was using a machine similar to a bi-level set with IPAP = 9 and EPAP = 6.) My AHI values were fantastic (always below 1.0) and my leak line was fabulous. But the severe aerophagia triggered a whole cascade of negative affects on my sleep and the quality of my life took a sharp nose dive in the first two weeks I was on CPAP. The PA who was in charge of my treatment ordered a switch to APAP (wide open) for a week of titration to see whether my pressure could be reduced.
APAP was less uncomfortable and at the end of the titration, the PA agreed to simply switch me to APAP with a range of 4-8 cm. EPR was still set at 3, and what this meant was that both IPAP and EPAP started at 4cm. As events or snoring or flow limitations occurred, the IPAP increased, first to 5, then to 6 and then to 7. When the IPAP = 7, the EPAP was still at 4cm. When IPAP was bumped up to 8, the EPAP increased to 5. My AHI was not quite so great, but it was still very good (AHI mostly between 1.0 and 2.5), but the aerophagia continued to be a problem on most nights and the CPAP-induced insomnia was growing fat and strong. Moreover, I was pretty constantly aware of the slight increase in pressure towards the end of my exhalations when the IPAP > 4 and I constantly felt as though the machine was rushing me to inhale before I was done exhaling.
About 2 months into my PAP nightmare, the doc and PA talked with each other (but not me), and at my next semi-emergency meeting with the PA, she said all they'd been able to come up with was the idea of seeing if I'd do any better on bi-level than APAP.
My first bi-level titration resulted in a script for bilevel at IPAP = 8; EPAP = 6. Which is a really weird bilevel script since PS = 2. For a whole lot of reasons that I don't want to get into here, I wound up with a PR System One (Series 50) BiPAP Auto set in fixed bilevel mode with IPAP = 8; EPAP = 6.
The difference in comfort was remarkable. With the BiPAP, I could tolerate being awake in the middle of the night for more than 10-15 minutes without throwing a screaming hissy-fit at hubby about how deeply uncomfortable (and unfair!!!!) all this PAP mess was.
I continued to have some problems with aerophagia and a lot of problems with generally very restless sleep, lots of bedtime insomina, and lots of sleep maintenance insomia. The PA sent me back to the lab for another bi-level titration, that resulted in a script for IPAP 7; EPAP = 4. My stomach could tolerate that without any aerophagia, and my sleep was marginally better (I was also doing hard core CBT-I for the insomnia). But, unfortunately, the titration night was a "good" night OSA-wise, and at home the AHI was bouncing all over the place with a fair number of AHI > 3.5 and 4. And the machine was scoring a lot of snoring. And hubby was confirming the snoring.
And that's when I wound up being switched to Bi-level Auto with the crazy settings that I still use: Min EPAP = 4, Max IPAP = 8, min PS = 2, max PS = 4. Most nights the IPAP is at 8 for most of the night; my EPAP usually stays between 4 and 5, but occasionally gets bumped up to 6 for 30-60 minute stretches. And the stomach can tolerate all this, and my sleep is ranges from "half-decent" to "decent" in terms of the insomnia.
Quote:3. Finally, I have an opportunity, assuming things progress, to get at a terrific price a Respironics 750p which I think is
"Respironics PR System One REMstar BiPAP Auto w/ Bi-Flex"
(does 750p automatically equal precisely and totally that? Or are some 750p's not bi-flex, or not Auto, or not BiPAP, for example?)
The 750p is the exact machine I use. It is the slightly older Series 50 System One BiPAP Auto. It has no heated hose option. The humidifer cannot be preheated. The LCD does not have 1-day data available. And the min PS = 2
in Auto mode cannot be changed. But those are really the only things different between the 750 BiPAP Auto and the 760 BiPAP Auto.
The "p" in the model name indicates it was originally bundled with a (Series 50) System One Humidifier, as I recall.
The 750p System One BiPAP Auto can be run in:
- Fixed CPAP mode
- Fixed bilevel mode
- Auto bilevel mode
Because min PS = 2
there is no way to effectively turn the 750p into an APAP, although setting the (max) PS = 2 will mean that it will run very similar to the S9 AutoSet with EPR = 2.
It's also worth pointing out that the Flex systems on the PR machines are not like the Resmed EPR system. The Flex systems do drop the pressure at the beginning of each exhalation, but the drop is NOT by a fixed amount. The size of the drop depends on the forcefulness of the exhalation. And even with Flex = 3 and a very forceful exhalation, the pressure is probably only going to drop by 1.5-2.0 cm. The pressure increase starts sooner in Flex than it does for EPR.
All that said, the 750p is a really nice machine. If it's a good price and you want to see what bi-level feels like with a PS = 4 or 5, it's worth considering.