BIPAP AUTO-SV SETTINGS HELP

Happy to see that the two of you agree to disagree. It was getting a bit testy.
Last night was weird with the new settings. The first 4 hours or so yielded AHI=0. The last four hours were not pretty. AHI for the night was 7 with 5 AI. Tidal volume stayed about normal at 543 and peak flow 27.7. BPM was low for me at 96.3, but much better than the original post on this topic. Leaks were normal at 41 with large quattro. (I usually get 36 with the medium quattro - no knowledge why the two sizes differ in average leak.)

Peak IPAP was 16.4 while my long term average is about 15.7. No PB.

I am guessing, but my wife noticed that I seem to always wake up on my back (supine). My data has always shown that most apneas and hypopneas occur when I am on my back. Tennis balls, pillows, etc. never worked to keep me on my side.

Banned - any chance I could call you or email you will scans of some of the daily detail data? Don't know where to go from here.

PKNUT1197@AOL.COM

Just want to add 0.2 c worth re Rise Time.

That Rise Time is not 5 millsecs Banned but 500 millisecs (half a second).

People who set their machines to max Rise Time without an Resp Therapist's advice can be misled into thinking they have just made their machine 'most' comfortable but as SWS painstakingly pointed out, they are in fact reducing the available tidal volume & that in turn reduces their nominal airflow & oxygenation. Doing that in combination with changing the BPM to manual & without well thought out I:E settings is surely going to guarantee messed up respiration.

Banned I am hearing clearly that you have a very intimate understanding of your machines & also what works for you but you must also be aware that you can train yourself to get used to odd settings even when some odd settings are not doing long term good (such as setting Rise Time to its max period of time).

But as always, a discussion like this sure gets one thinking

DSM

CROWPAT wrote: Banned - any chance I could call you or email you will scans of some of the daily detail data? Don't know where to go from here.

Crowpat,

Please put your scans of your daily data on this thread for all to see and perhaps venture their opinions so you can reap maximum input and benefit. I do not know how to post a scan, but I'm sure DSM or others can let you know how to do it. I look forward to seeing your data on this thread!

Thanks,
Banned

dsm wrote: Banned I am hearing clearly that you have a very intimate understanding of your machines & also what works for you but you must also be aware that you can train yourself to get used to odd settings even when some odd settings are not doing long term good (such as setting Rise Time to its max period of time).

But as always, a discussion like this sure gets one thinking

So let's assume that a person trains themselves to odd BPM, Ti, RT, EPAP, or IPAP settings and they still yield 0 AHi. Where might be the long-term harm?

Banned

Banned wrote:

dsm wrote: Banned I am hearing clearly that you have a very intimate understanding of your machines & also what works for you but you must also be aware that you can train yourself to get used to odd settings even when some odd settings are not doing long term good (such as setting Rise Time to its max period of time).

But as always, a discussion like this sure gets one thinking

So let's assume that a person trains themselves to odd BPM, Ti, RT, EPAP, or IPAP settings and they still yield 0 AHi. Where might be the long-term harm?

Banned

Banned

I agree that 0 AHI is a *great* target but am sure we would all agree it doesn't tell the full story. Someone can have 0 AHI and still have their tidal volume sub optimal (e.g. such as having set their Rise Time too long).

Cheers

DSM

Snippets from Encore Viewer are lousy resolution, but here they are: top one is a fairly normal but better than average night. Bottom one is last night with Backup Rate at 10, etc. I will leave these up on one of my sites for a few days.
http://www.afsashoot.com/PAT1.html

Crowpat

There are enough apneas there for me to wonder if the epap is set adequately. Leak looks acceptable so epap gets the spotlight.

Also, (although faint in the images) I see the SV algorithm seems to be active pretty well all the time. That could be it attempting
to use SV to clear obstructive apneas, or it responding to central apneas ? - if responding to centrals I might expect to see more
hypopneas than are showing.

On further looking at the chart
Epap = 12 IPAPmin = 14 (Hmmm epap shd be ok at that)

So what is causing those apneas & are they obstructive or central ? (the BPM might be a clue)

Cheers

DSM

I have mostly obstructive apneas, but DO have centrals. That is why I switched to the SV versus the APAP. I have generally had a low HI regardless of machine or settings, but the AI varies quite a bit with changes in the pressure settings. It took me several months to settle on the 12/14 base numbers with backup set to auto.

Banned wrote: Thanks for that bit of arbitrary ASV knowledge!

Absolutely nothing arbitrary there, good sir. Maximizing perceived comfort can sometimes literally undercut treatment objectives. An extreme example: no CPAP at all is faaaaar more comfortable than therapeutic CPAP pressures in very many cases.

Banned, your other comment was that CROWPAT's average tidal volume seemed okay'ish with a rise time of 5. I think that kind of average tidal flow analysis is much better for sustained ventilatory problems like COPD, hypoventilation, etc.---problems where flow averages are truly tell-tale. CSDB/CompSAS, on the other hand, is a disorder where small and transient flow/pressure deltas can cause problems that are unpredictable and disproportionate. On that same note...

Does anybody remember this thread where Kolchak got his AHI down to below 2 with that final tweak of changing rise time from 5 to 3?
viewtopic.php?f=1&t=32951&p=280896&hili ... me#p280896

Kolchak wrote: FYI - after changing the rise time to 3 my AHI droped down to 2! Think I'm set up perfectly now.

That turned out to be more than just a comfort setting.

And, Banned, backup rate and T(i) settings are never primarily comfort settings. Sir Banned, if you have medical literature to the contrary... I'm the one who's all ears this time.

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CROWPAT wrote:It took me several months to settle on the 12/14 base numbers with backup set to auto.

Okay. I assume that's what brings you to wanting to explore a manual backup rate this time around instead of EPAP and IPAP settings.

Do you mind my asking exactly what happened to your sleep data and quality of sleep when you experimentally set IPAP_min to IPAP_peak average? Also wondering what happened when you experimentally set EPAP around IPAP_peak average? My assumption is that you've already been up and down that road in your past experiments.

CROWPAT wrote:Snippets from Encore Viewer are lousy resolution, but here they are: top one is a fairly normal but better than average night. Bottom one is last night with Backup Rate at 10, etc.

Do you happen to have a graph handy that shows us what you were hoping to fix: an average or even worse-than-average night, but while using auto BPM instead of 10?

I never tried setting Ipap min to Ipap avg as that would have yielded a pressure far above what I have found workable for me, nor did I try the other. There is no question that I have centrals when Ipap or Epap is above 14 or so. My original CPAP setting was 13 so when I bought an APAP I changed many settings over several months trying to get a week of data before making another change. I found that I did best at 11-13 on the low end and around 17-18 on the high end. When I bought the SV I again tried many different settings, but always with the high end 10 above whatever Ipap I selected. Your comments on rise time settings was interesting and all new to me. I have always been concerned that my Tidal Volume was lower than other people at around 540 or so. If max rise time setting inhibits tidal volume as I understood you to say then I need to lower that setting to get more volume and better oxygenation.

In short, I have had years of CPAP/APAP/SV use, but never changed settings until I found this board. Thereafter, I have been fairly agressive in trying to minimize my AHI along with leaks. I felt I was quite successful when my AHI stayed in the 2.0 area over several months and leaks were very low to none for almost all nights when my face and mask seals were clean/not oily.

I have never felt that surge of daytime energy that some others (including several local friends) experienced from machine use. That is why I started this thread. Numerous doctors have tried to find a solution (other than CPAP) and none have been successful.

If I am barking up the wrong tree by fooling around with manual backup settings I want to know it, and I will go back to the auto backup settings along with lowering the rise time from max and live with the AHI of 2 or so.

My thanks to each of you for taking the time to comment and offer information as well as advice.

Crowpat

Be sure that experimenting can be a way forward for many of us & that the settings your are adjusting are thus far ones that you can survive the consequences of. What I hope you are getting out of the discussion (just as I am) is a broader understanding of what some of these settings mean and are there for and can do.

For example, as I understand it, the very long rise time setting is there to be used for people with lung problems (COPD) where a more aggressive (but otherwise acceptable) rise time causes them both discomfort and other complications. But, the cost for extending rise time is reduced airflow. But, that can often be compensated for with other adjustments (epap-ipap gap & BPM timing etc: ). Cpap therapy is often a juggling act between the different settings & their side effects.

You are certainly helping yourself by discussing your goals & allowing us to explore what is taking place.

DSM

CROWPAT wrote: If I am barking up the wrong tree by fooling around with manual backup settings I want to know it, and I will go back to the auto backup settings along with lowering the rise time from max and live with the AHI of 2 or so.

Hi CROWPAT,

You do not have to live with an AHi of 2 or so.

Please consider SWS's recommendation of returning to AUTO BPM for now. In any event, RT 5 is probably not appropriate (as SWS and dsm suggest). You are more than likely obstructive, and not restrictive. Table the manual BPM for now and go back to AUTO.

The real concern (to which SWS and dsm have also eluded) is that your EPAP 12/IPAP Min 14 spread of 2 cmh20 is highly suspect. I do not know if it is a Respironics protocol, but the sleep medicine community is in agreement that effective bi-level therapy begins with a minimum EPAP to IPAP spread of 4cmH20.

I begin all of bilevel self titrations with a minimum 4 cmH2O EPAP/IPAP Min spread. I have never considered or attempted a lower than 4 cmH2O EPAP/IPAP Min spread. For me, that sleep medicine recommendation has always worked perfectly, consistently, and with numerous exotic Bi-level machines. To me, the minimum Bi-level 4 cmH2O EPAP/IPAP Min spread is the one single, most useful, piece of advise the sleep medicine community can ever give you. You will find many ill informed people on this board who own a BiPAP Auto SV who are either ignorant or choose to ignore that recommendation.

To effectively reduce your AHi I think you need to focus on increasing your EPAP/IPAP Min spread so the machine has more latitude to address all of your apnea components. If you would, please consider providing us a look at one night worth of data with the following settings:

1. EPAP 12cmH20
2. IPAP Min 15cmH20
3. BPM AUTO

You will still not be at the recommended 4 cmH20, but you will know if it is step in the right direction. I'm sure you can see where I'm headed with this.
There are many opportunities to get to that "magic" 4 cmH2O spread.

What I have done on both the AVAPS, BiPAP Auto SV, and VPAP Adapt SV is address the AHi components as close as I can while maintaining that all-important 4 cmH20 Bi-Level EPAP/ IPAP Min spread. Than, if you still miss the mark, you can try dialing in a manual back-up rate to see if there is any improvement.

Banned

Last night with rise at 5 instead of 6(max) was not very comfortable to me. AHI 5, AP 2, peak flow 28.3, tidal volume down to 525, avg BPM 14.4, patient triggered breaths at 98.3, and avg leak on target at 41.0. I have not had a good night since I started this fixed BU Rate experiment.

I looked at nearly a year's worth of data and found that I only tried an E/Ipap separation of 3 once. I have been on 12/14 with Ipap Max at 22 for almost the entrie year with AHI average by month at just over 2. I did not record my data on a spreadsheet for earlier use of the SV machine.

I will try the 3 unit separation tonight at 12/15, but think that Ipap(min) number is too high for comfort. You said that that would give the machine more room to move pressure, but I don't see how since Epap is fixed and only Ipap varies.

CROWPAT wrote: I will try the 3 unit separation tonight at 12/15, but think that Ipap(min) number is too high for comfort. You said that that would give the machine more room to move pressure, but I don't see how since Epap is fixed and only Ipap varies.

I understand that IPAP Min 15 maybe more 'uncomfortable'. The other option for tonight is EPAP 11 and IPAP Min 14. Either way, you will want to experiment with those two pressures. Many people (including dsm) use a EPAP/IPAP Min separation of 3 cmH20 on their BiPAP Auto SVs. It probably comes from their previous EPR/C-Flex experiences during their CPAP days. I have never heard of anyone using only two cmH2O separation on a Bilevel machine. That would be getting pretty close to traditional CPAP therapy, with the caveat that you can perhaps still address centrals.

Banned

Banned, note that my original and following titrations with CPAP were for 13 to clear obstructive apneas. Good to know that my Ipap/Epap separation of 2 is not common. I will change the SV again to 11/14 for tonight with rise at 5 and give it a go. Will post results for all of you.