BiPAP Auto SV settings questions

[BefuddledByPAP]

Been reading the forum on and off for several months and finally got registered a few days ago. I've learned a ton from y'all, but still have a boatload of questions. Have quite a story to tell as well, but I often have a lot of difficulty writing things down. So that will have to wait.

First up - and thanks to John and others who have already helped and encouraged me along these lines - a question regarding the function and settings of the Respironics BiPAP Auto SV (also called ResMED BiPAP Auto SV I recently found out - though there is no mention of ResMED on my machine or in the operating manuel, etc. ... very frustrating).

After two difficult sleep studies (initial AHI = 45, emerging central AHI = 125) my Rx/order was: "Auto SV, min. expiration = 11." That's all. The DME provider's RT said that the Dr. should have indicated a minimum inspiratory pressure as well. He also said that the minimum inspiratory pressure had to be higher than the minimum expiratory pressure, so he arbitrarily set it 12. He also set the maximum inspiratory pressure at 21 without explanation - though I have since learned this is normal practice.

Anyway, after a few months of only moderate improvement and increasingly intollerable side-effects, I purchased the Encore Viewer and Pro software and reader, a pulse/oximeter and the ZEO sleep recorder. Then I carefully and thoughtfully began to search for more effective settings on my own.

After some really difficult trials, I finally settled on Min E = 8, Min I = 8, Max I = 18. While this violates the "Min I must be greater than Min E rule," it seems to have eliminated the tendency of this machine to fight my breathing through much of the night. And with these settings, my average AHI is in the 4-6 range, my average periodic breathing is in the 2%-5% range, my SpO2 @ 2-3 events/95%, and pulse events 3-5, bpm = 55, low bpm usually in the upper 40's.

Is the machine functioning as it was designed with Min E = Min I ?

Is there another machine which would provide the same support AND allow me to access the breath-by-breath waveform data?

[CROWPAT]

The Bipap Auto SV is made by Respironics, not Resmed. Resmed makes a completely different SV machine - VPAP Auto-SV.
Your settings have turned yours into a CPAP Auto machine which is one of its' capabilities. When you have IP and EP set at the same number it is in CPAP mode. When you include a maximum IP along with the other two numbers being the same it is in Auto CPAP mode. Only when you have IP > EP and max IP about 10 higher than IP Min is it in SV mode. The fact that your AHI has improved dramatically raises the question of why you are on an SV machine. How are your leak numbers? If you have high leak numbers all data is void and you will have to start over with your self-titration.
Your machine is the most versatile machine out there. John (if the same one) helped me get mine right too, but he primarily uses an ASV.
Rise time is a comfort setting that makes the transition from EP to IP go smoother. Mine is set on 4, but you can set it from 1 to 5 for your own breathing comfort. If I set mine at 2 (for example) I am fighting the IP transition on the machine all night and do not sleep well, or get good therapy.
You show BPM (breaths per minute) as extraordinarily high numbers. Mine has been 14.3-15 for years. Did I misinterpret your original posting?
Cannot comment on wave form data as I have never been able to get it (or CA data for that matter) on either Viewer or Pro 2.4.
Pat

[-SWS]

Your settings have turned yours into a CPAP Auto machine which is one of its' capabilities. When you have IP and EP set at the same number it is in CPAP mode. When you include a maximum IP along with the other two numbers being the same it is in Auto CPAP mode. Only when you have IP > EP and max IP about 10 higher than IP Min is it in SV mode.

Hey, Crowpat... Good to see you! I respectfully disagree with your above comment.

Min E = 8, Min I = 8, Max I = 18.

Those settings are, indeed, legitimate Respironics auto servo ventilation settings. At those particular settings, the machine will: 1) deliver 8cm CPAP modality during those moments when no servo ventilation is needed, but 2) proportionally deliver an IPAP pressure between 8cm and 18cm when servo ventilation is needed (respiratory "undershoot" on your part). That's not what an ordinary APAP machine does.

While this violates the "Min I must be greater than Min E rule,"

There is no Respironics AutoSV rule stating that. Are you sure you have an AutoSV by Respironics? Substitute the words "greater than or equal to" for the Respironics BiPAP autoSV.

[quote=""BefuddledByPAP"]Is the machine functioning as it was designed with Min E = Min I ? [/quote] If that really is a Respironics AutoSV and it's set up as you stated above, you are running your machine in one of the Respironics recommended modes. And Respironics even purports that mode to address central apneas and periodic breathing.

[Banned]

When you include a maximum IP along with the other two numbers being the same it is in Auto CPAP mode. Only when you have IP > EP and max IP about 10 higher than IP Min is it in SV mode.
Pat

Close, Crowpat, but incorrect.
When you include maximum IPAP along with the other two numbers being the same it is in CPAP mode with ASV (not Auto CPAP mode).

Banned

[BefuddledByPAP]

Pat,

Thanks for your reply. Sorry it takes me so long to respond. Fuzzy brain and slow typing ... And sorry about the "ResMED" reference - I meant RemStar. I didn't realize until recently (when I couldn't find my machine on the forum registration pull-down menu) that Respironics and RemStar were one and the same. Too many models and acronyms for me to keep track of.

It makes sense that the setting I indicated (Min I = Min E) would equate to Auto CPAP.

However, on this setting, if I stop breathing for about six seconds or so, the machine still gives me what feels like the same "I'm taking this breath for you / pulse of air" that I feel when I have the Min I > Min E. Also the Daily Details generated pressure profiles for both settings appear consistent. And the average peak IPAP is also very consistent at 2 to 2.5 above the Min EPAP (again, per the Daily Details readout).

Is all this consistent with Auto CPAP? Is it possible that the SV capability functions independently of BiPAP?

My Rise Time setting is 2. I spent considerable time finding my comfort zone there as well.

The bpm I am referring to is heartbeats per minute per the pulse-oximeter. My breaths-per-minute average is about the same as yours ... about 13.5. It ranges from about 9 to 16. BTW, I should note too that my breaths-per-minute setting on the machine is "Auto." I guess you figured that.

Again thanks for your insight and comments.

Paul

[-SWS]

It makes sense that the setting I indicated (Min I = Min E) would equate to Auto CPAP.

No, sorry... But it does not make sense.

Auto CPAP delivers gradually-changing STATIC pressure. By stark contrast the settings you have deliver highly dynamic and proportional IPAP when your individual breaths happen to "undershoot". That's servo ventilation.


In the red box to the left we see the Respironics autoSV machine delivering SV mode on the top line. In your case IPAP delivery fluctuates, per breath, between 8cm and 18cm during SV-mode moments. In the narrow, red box just to the right of that, we see the machine delivering CPAP pressure only (EPAP=IPAPmin) because respiratory undershoot did not occur. In your case, that's exactly 8cm getting delivered during those CPAP moments.

So your machine is correctly set up to do what we see in the picture above: 1) deliver CPAP mode when there is no respiratory "undershoot", but 2) deliver SV mode when there is "undershoot" in the patient's breathing.

That's one servo ventilation mode recommended by Respironics.

[CROWPAT]

SWS and Banned have lectured me for years. They both know more about this machine than I ever will so I am happy to be corrected and defer to them.
I tried 11/11/22, 12/12/22, and 13/13/22 for about ten days each and found that the 12/14/22 settings I came up with over time gave me better long term numbers.
Pat

[BefuddledByPAP]

Thank you so much SWS, Banned and CrowPat,

Your explanation makes perfect sense. Wish I had been able to get this question out and answered months ago. For me, the I = E setting is as effective as I > E and the awful pounding/forced breathing is no more. Would love to know what there is about my breathing architecture which causes the machine to respond that way. Anyway, taking the Doctor's and RT's word as gospel is a lesson learned.

Again, any suggestions on how I might be able to get a look at my waveform data without another sleep study?

[-SWS]

Again, any suggestions on how I might be able to get a look at my waveform data without another sleep study?

BBP, unfortunately your machine model does not offer the detailed flow waveform graphs typical of the PR System 1 or the S9 models.

Is there another machine which would provide the same support AND allow me to access the breath-by-breath waveform data?

Not yet for SV machines... Some day soon I hope.

[Banned]

Is there another machine which would provide the same support AND allow me to access the breath-by-breath waveform data?

Not yet for SV machines... Some day soon I hope.

Enter PR System 1 ASV

[JohnBFisher]

Is there another machine which would provide the same support AND allow me to access the breath-by-breath waveform data?

Not yet for SV machines... Some day soon I hope.

Enter PR System 1 ASV

Agreed. Either the Respironics PR System 1 ASV or the ResMed S9 based ASV, both of which I understand are in the works. But for the forseeable future the current crop of machines do not produce the detailed data.

[JohnBFisher]

Glad you were able to resolve your username issue. Also am glad to see that you got such wonderful answers (as usual) from -SWS. As he noted, you have your machine in CPAP mode with the ASV assist when you fail to breathe. You noted:

... After some really difficult trials, I finally settled on Min E = 8, Min I = 8, Max I = 18. While this violates the "Min I must be greater than Min E rule," it seems to have eliminated the tendency of this machine to fight my breathing through much of the night. And with these settings, my average AHI is in the 4-6 range, my average periodic breathing is in the 2%-5% range, my SpO2 @ 2-3 events/95%, and pulse events 3-5, bpm = 55, low bpm usually in the upper 40's. ...

You CLEARLY found some settings that work well for you. Good for you! Eventually you may want to let your doctor know about the changes in the pressure. But be certain to provide information about the before and after results (via graphs). Also when you do any follow up sleep studies, let them know the current settings. That way if they want to tweak they can START from what you currently use.

As I noted, the current bumper crop of ASV machines (from Respironics and Resmed) does not provide the breath by breath detailed data. There is a significant lag time behind the current technologies for the ASV machines. Though the technology behind the ASV machines helped drive technology that has since been incorporated into the CPAP and BiPAP machines, the cost to develop ASV machines means that the development cycle is longer for ASV machines. (These machines have to go through the same regulatory approval process, but have far fewer potential customers. Thus, the cost to develop can not be spread across as many units.)

So, here's hoping you continue to have such good results!