Need help with ASV

[moresleep]

The earliest model Respironics Bipap Auto SV does not have Auto Bipap functionality; the two latest models do.

That would not be "Auto Bipap" in the Classic Algorithic Sense, in that all obstructive events would need to be managed by EPAP; in the CAS, IPAP (or PS) plays a significant role in the management of hypopneas and flow limitation (Popt).

The advertising literature, including that of our sponsor, describes the Auto SV Advanced as being capable of an Auto Bipap mode: "The BiPAP AutoSV Advanced now comes with an Auto-titrating algorithm that allowing the device to operate like an Auto CPAP or Auto Bilevel device." I don't know anything about the algorithym used, but those most likely vary considerably from machine-to-machine, anyway.

[NotMuffy]

The earliest model Respironics Bipap Auto SV does not have Auto Bipap functionality; the two latest models do.

That would not be "Auto Bipap" in the Classic Algorithmic Sense, in that all obstructive events would need to be managed by EPAP; in the CAS, IPAP (or PS) plays a significant role in the management of hypopneas and flow limitation (Popt).

The advertising literature, including that of our sponsor, describes the Auto SV Advanced as being capable of an Auto Bipap mode: "The BiPAP AutoSV Advanced now comes with an Auto-titrating algorithm that allowing the device to operate like an Auto CPAP or Auto Bilevel device."

However, the need (or choice) of moving to bilevel or autobilevel therapy is frequently based on seeking greater comfort while insuring effective therapy. This is achieved by setting EPAP at the lowest possible level (that which overcomes all obstructive apneas and addresses vibratory snores), then attacking other events (obstructive hypopneas and RERAs (algorithmically presumed as flow limitations) with IPAP.

This approach cannot be accomplished with the settings you describe.

I don't know anything about the algorithym used, but those most likely vary considerably from machine-to-machine, anyway.

Yes they do, which should prompt people to exercise their due diligence before selecting a machine.

[robysue]

That would not be "Auto Bipap" in the Classic Algorithic Sense, in that all obstructive events would need to be managed by EPAP; in the CAS, IPAP (or PS) plays a significant role in the management of hypopneas and flow limitation (Popt).

and

However, the need (or choice) of moving to bilevel or autobilevel therapy is frequently based on seeking greater comfort while insuring effective therapy. This is achieved by setting EPAP at the lowest possible level (that which overcomes all obstructive apneas and addresses vibratory snores), then attacking other events (obstructive hypopneas and RERAs (algorithmically presumed as flow limitations) with IPAP.

This does describe how the PR System One BiPAP Auto works (except for one twist). The PS setting on the System One is the maximum IPAP-EPAP allowed. Pressure levels work as follows:

• At the start of the night:
  • EPAP = min EPAP and IPAP = EPAP + 2
  Pressures are INCREASED as follows:
  • When the machine detects hypopneas, RERAs, and flow limitations:
    • If IPAP - EPAP < PS, JUST the IPAP is increased---until the problem is resolved OR IPAP-EPAP = PS OR IPAP reaches the max IPAP setting.
    • If IPAP - EPAP = PS, then BOTH the IPAP and EPAP are increased---until the problem is resolved OR IPAP reaches the max IPAP setting.
    • If IPAP = max IPAP, then neither IPAP nor EPAP is increased.
    When the machine detects OAs and vibratory snores:
    • If IPAP - EPAP > 2, JUST the EPAP is increased---until the problems is resolved OR IPAP-EPAP = 2 is reached.
    • If IPAP - EPAP = 2, BOTH the IPAP and EPAP are increased---until the problem is resolved OR IPAP reaches the max IPAP setting.
    • If IPAP - EPAP = 2 AND IPAP = max IPAP, then neither IPAP nor EPAP is increased.
  It is important to note too, that the PR System One does use the Resprionics "hunt and peck" algorithm for raising the pressure periodically to see if the wave flow improves (as defined by that mysterious Popt variable) even in the absence of events. The hunt and peck algorithm ONLY raises the IPAP pressure, however. It does NOT affect EPAP if IPAP - EPAP < PS.

The S9 VPAP Auto, on the other hand, uses the PS setting as the fixed difference between IPAP and EPAP. In other words, on the S9 VPAP Auto, it works like this:

• At the start of the night:
  • EPAP = min EPAP AND IPAP = min EPAP + PS
  Pressures are increased as follows: When the machine detects OAs, hypopneas, flow limitations, and vibratory snores:
  • If IPAP < max IPAP, then both IPAP and EPAP are raised (so IPAP - EPAP = PS at all times)
  • If IPAP = max IPAP, then neither IPAP nor EPAP are increased.

So a pair of questions to NotMuffy:

1) Does this mean that the Resmed S9 VPAP Auto algorithm is the "Classic Bi-level Algorithm" and the PR System One BiPAP Auto's algorithm is attempting to better mimic what actually goes on in a bi-level titration study?

2) Which in your opinion is more likely to provide more comfort for a person who is being switched to BiPAP Auto primarily for comfort reasons? (I.e.for folks can't seem to sleep with straight CPAP/APAP and/or has serious aerophagia problems with straight CPAP/APAP even with pressure relief turned on.)

I don't know anything about the algorithym used, but those most likely vary considerably from machine-to-machine, anyway.

Yes they do, which should prompt people to exercise their due diligence before selecting a machine.

Ah, yes, but how is the user who is facing a choice between the S9 VPAP Auto and the PR System One BiPAP Auto supposed to exercise that due diligence: DMEs won't typically allow you to try out the blower for 15 or 20 minutes before you make the decision.

[NotMuffy]

Does this mean that the Resmed S9 VPAP Auto algorithm is the "Classic Bi-level Algorithm" and the PR System One BiPAP Auto's algorithm is attempting to better mimic what actually goes on in a bi-level titration study?

I think the term "Classic Bi-Level Algorithm" should be reserved for the original Respironics AutoBipap.

It's underlying approach is (was) in keeping with the current AASM Clinical Guidelines:

http://www.aasmnet.org/Resources/clinic ... 040210.pdf

Which in your opinion is more likely to provide more comfort for a person who is being switched to BiPAP Auto primarily for comfort reasons? (I.e.for folks can't seem to sleep with straight CPAP/APAP and/or has serious aerophagia problems with straight CPAP/APAP even with pressure relief turned on.)

Aerophagia (and certainly "serious aerophagia") would more appropriately be termed a "complication" of xPAP Therapy. I believe "comfort measures" would pertain to "those adjuncts that improve the ability to tolerate xPAP during Wake". Chances are that if a person is fine with therapy during Wake and Pressure Approach is reasonable, nothing that the algorithm does during the night should disturb sleep.

If it does, or one thinks it does, I would be looking for a "Sleep Problem" instead of a "Sleep-Related Breathing Problem".

As an aside, there are certainly plenty of other "Comfort Measures" built into this technology. For instance, it may simply be the "Easy Breathe" waveform in ResMed machines that allow increased compliance in patients that claim ASV technology is the Deal Maker (and if we are saying that Comfort Measures are a Wake Phenomenon, then that most certainly should be the case).

...but how is the user who is facing a choice between the S9 VPAP Auto and the PR System One BiPAP Auto supposed to exercise that due diligence: DMEs won't typically allow you to try out the blower for 15 or 20 minutes before you make the decision.

• If someone is reading this, then they can read enough around here to make a reasonably informed decision.
• I would challenge anyone to show objectively that one machine is so superior to all others that the decision becomes a no-brainer (and that includes off-label use of ASV advocated by one poster, who basically says "Well, it works, but it's Magic, so I can't tell you.").
• I think it's important to stress that point so people won't think "Omigod! I don't have a Lexus GL500 xPAP so I'm going to die!"
• I believe there is opportunity to try out machines from a DME if you do it prior to actually committing to the DME ("Say, I'm thinking on using your company. Can I suck on your machines for a while?")
• TS, 15-20 minutes may not be sufficient to completely evaluate a machine.
• TS about TS, I have to admit there have been some waveforms where after 3 breaths I've said "Whoa, I think you've got something here!"
• Does Johnny have a return policy?

[NotMuffy]

I would challenge anyone to show objectively that one machine is so superior to all others that the decision becomes a no-brainer...

TS3, I suppose there are a few rocks out there.

[NotMuffy]

And on that note, this chiliaphobe is headed down to the store for 50 pounds of sugar and a hundred rolls of toilet paper to get ready for Irene!

See ya!