BIPAP AUTO-SV SETTINGS HELP

General Discussion on any topic relating to CPAP and/or Sleep Apnea.
CROWPAT
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BIPAP AUTO-SV SETTINGS HELP

Post by CROWPAT » Tue Nov 24, 2009 9:28 am

I have been on the SV machine for nearly two years with AHI averaging a bit over 2 once I dialed it in. In early mornings I was not breathing good so I decided the auto setting for BPM backup should be tweaked to force breathing during that period of about an hour before I really wake up. Last night I set it to 12 BPM backup and 2.5 (max) for inhalation time. Disaster. AI went to 19 and average patient triggered breaths went down to 85.6!

My normal settings are IPAP 14-22. EPAP 12. (Average Peak IPAP is 15.7 long term.) Avg Peak Flow 27-9. Avg Tidal Volume 545. Historical BPM is 14. Avg Patient Triggered Breaths are generally 99.7-99.9. Large Leaks are usually 0. Avg Leak generally matches the Quattro profile, but oddly is 40 with a large mask and 36 with a medium. Very few leaks with the Quattro if the seal and face are clean and face oil free.

Why did I change what was giving good numbers? Still tired after I am up for an hour or so, and my belief that I was not breathing well just before waking. Charts showed that many of my events occured during the last hour of sleep.

Anyone have any idea what is going on and what to change to get the Backup Rate Setting right? (If that is the problem)
Pat

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JohnBFisher
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Re: BIPAP AUTO-SV SETTINGS HELP

Post by JohnBFisher » Tue Nov 24, 2009 10:18 am

CROWPAT wrote:... Why did I change what was giving good numbers? Still tired after I am up for an hour or so, and my belief that I was not breathing well just before waking. Charts showed that many of my events occured during the last hour of sleep.

Anyone have any idea what is going on and what to change to get the Backup Rate Setting right? (If that is the problem)
I doubt I'm able to help much with the backup rate. I am waiting for an AutoSV unit myself.

Do you know what the backup rate was before you changed it? AUTO perhaps? You might want to change it back.

Why are you having problems? I suspect you have similar problems as I do. It appears that during light stages of sleep (usually when falling asleep or waking), I simply stop breathing. Though some central apneas during sleep transition are normal, for some of us the central apneas are constant. Anytime I fall asleep I stop breathing. Long enough that it forces my body to wake me. I can tell when I had problems during the waking side of it. I tend to wake with monster headaches. During my last sleep study with an AutoSV unit, I woke feeling more rested than I have in months (or since). I guess it is a good sign that I wanted to walk out the door with the unit the sleep lab had.

I am guessing the change in the backup rate caused your body to struggle more than it would otherwise. I found that sleeping with the unit it took me a couple hours to get used to the "follow the leader" feel of sleeping with the unit. Once I did, as I noted, I fell deeply asleep.

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CROWPAT
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Re: BIPAP AUTO-SV SETTINGS HELP

Post by CROWPAT » Tue Nov 24, 2009 11:09 am

It was on Auto before I made the change.
Pat

-SWS
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Re: BIPAP AUTO-SV SETTINGS HELP

Post by -SWS » Tue Nov 24, 2009 11:11 am

CROWPAT wrote:In the early mornings I was not breathing good so I decided the auto setting for BPM backup should be tweaked to force breathing during that period of about an hour before I really wake up.
Well, the morning hours can be very REM intensive. And REM-intensive sleep can sometimes mean more obstructions. You can't know for certain whether your morning spikes are based in central dysregulation or airway obstruction. Even if you observe a noticeable increase in PB, initial obstruction may well serve as your morning catalyst---triggering subsequent spells of central dysregulation or upheaval.

That's, in part, why the Respironics and even Resmed SV titration protocols have the clinicians attempt to address the complete obstructive component first---in the Respironics case, preferably with either CPAP (EPAP = IPAP_min) or with a minimally disruptive pair of BiLevel pressures (EPAP < IPAP_min). I would also point out that the Respironics BiPAP autoSV titration protocol has the clinician resort to manual backup rate only after all possible EPAP, IPAP_min, and IPAP_max adjustment attempts have been tried. With your average spontaneous BPM at 14, a manual backup rate of 12 is correct. However, when the clinician turns off auto backup rate as a last-ditch effort to regain central control, the Respironics titration protocol asks for an I_time ("inspiratory time") setting of somewhere in the ballpark of 1.2 seconds---but not shorter. Yours is more than double that recommendation.

Again, as a friendly reminder: turning autobackup rate off is supposed to be a last-tier method according to the Respironics titration protocol. My understanding is that getting a manual backup rate set up just right in CSDB/CompSAS cases can be extremely difficult for even experienced technicians during a PSG.

CROWPAT wrote:Anyone have any idea what is going on and what to change to get the Backup Rate Setting right? (If that is the problem)
A couple other experiments (with backup=auto) might entail: 1) moving IPAP_min closer to IPAP_peak average, and/or 2) moving EPAP closer to IPAP_peak average.

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by CROWPAT » Tue Nov 24, 2009 11:20 am

SWS, thanks much for your usual great input. I think I need to write this off as a failed experiment and return the machine to auto.
Pat

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by Banned » Tue Nov 24, 2009 6:11 pm

I wouldn't necessarily call it a 'failed experiment'. Yes, it is easy to lulled back into into the "See your doctor, or Put it back on AUTO", mantra, but lets face it, you have an inquisitive mind. Probably more-so than any other BiPAP Auto SV user I've heard on this board. So let me bore you with my experience with manually dialing in BPM, inspiration Time (Ti), and Rise Time (RT) successfully on both AVAPS and a BiPAP Auto SV without a Dr's titration.

I learned how to set a manual BPM while logging 500 hours on AVAPS (which has no 'AUTO' BPM function) and 350 hours on a BiPAP Auto SV (where I still use a manual BPM because I find it more comfortable than when in "Auto' mode). On both machines with a manual dialed-in BPM, I'm at 0 AHi. It's not magic.

The literature says to set your BPM to 2-3 BPM below your Resting BPM. You would assume that setting your BPM for 12 would suffice since it is 2 BPM below your average BPM of 14. Your assumption is incorrect. at an average 14 BPM you will need to manually set your BPM for 10 maximum, probably more comfortable at 8. My Average BPM is 16 to 17,

Your problem is 12 BPM was forcing an EPAP-IPAP switch for you too soon.

To make matters worse, your Inspiration Time of 2.5sec was way too long (As SWS noted).

And you did not tell us where you had RT set at.

I would hope (since you seem to have an inquisitive mind) that you might try these manual settings and see if you do any better.

1. Set BPM to 10. Set BPM to less than 10 if you experience the machine is EPAP/IPAP switching too fast.
2. Set Ti at 1.8 (minimum). If the machine feels like it is switching from IPAP to EPAP too fast, than increase Ti in .1 increments. No offense to SWS, but there aren't many otherwise healthy (though over-weight/obese men with or without diabetes) who can breathe with as fast a Ti of 1.2sec.
3. Set RT to 2 or 3 if your breathing is 'obstructive' in nature. set RT to 4 or 5 if your breathing is 'restrictive' in nature. If you are unsure if your breazthing is obstructive of restive, set RT at 3.

Anyway, If your're happy on Auto, no need to respond. If you try something different, let us know. We could all learn from you.

Banned
AVAPS: PC AVAPS, EPAP 15, IPAP Min 19, IPAP Max 25, Vt 520ml, BPM 10, Ti 1.8sec, RT 2 (Garage)
BiPAP Auto SV: EPAP 9, IPAP Min 14, IPAP Max 25, BPM 10, Ti 2sec, RT 2 (Travel Machine)
VPAP Adapt SV: EEP 10.4, Min PS 4.4 (Every Day)
Mask: Quattro

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by Banned » Tue Nov 24, 2009 6:28 pm

-SWS wrote:[
Again, as a friendly reminder: turning autobackup rate off is supposed to be a last-tier method according to the Respironics titration protocol. My understanding is that getting a manual backup rate set up just right in CSDB/CompSAS cases can be extremely difficult for even experienced technicians during a PSG.
SWS,

I won't dispute that Respironics included that protocol for the sake of simplicity and expedience. But if you have any rational/argument that BPM, Inspiration Time, and Rise Times are any more than comfort settings, I'm all ears.

Banned
AVAPS: PC AVAPS, EPAP 15, IPAP Min 19, IPAP Max 25, Vt 520ml, BPM 10, Ti 1.8sec, RT 2 (Garage)
BiPAP Auto SV: EPAP 9, IPAP Min 14, IPAP Max 25, BPM 10, Ti 2sec, RT 2 (Travel Machine)
VPAP Adapt SV: EEP 10.4, Min PS 4.4 (Every Day)
Mask: Quattro

CROWPAT
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Re: BIPAP AUTO-SV SETTINGS HELP

Post by CROWPAT » Tue Nov 24, 2009 6:30 pm

Banned, I am really happy that you viewed and responded. Your opinions always make sense to me. My RT is at 5 right now - it just feels better to me.
Tonight I will try your BPM and T(i) recommendations, but leave RT at 5 and see what happens. I have the feeling that using a fixed BPM backup rate instead of auto may cure the late night events, or reduce them, and improve my AHI. I'll let you kow what happens.
Pat

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by -SWS » Tue Nov 24, 2009 9:00 pm

Banned wrote:But if you have any rational/argument that BPM, Inspiration Time, and Rise Times are any more than comfort settings, I'm all ears.
No disrespect to you, Banned, but you're pulling my leg, right? Sadly, I don't think you are.

Forget about the fact that the Respironics titration protocol very clearly tells clinicians to address only persistent central dysregulation with manual BPM and an I-time at 1.2 seconds. Forget that they fail to mention I-time as having anything to do with "patient comfort" as you say. Forget about manufacturer-protocol tier levels and the other methodology as well...

CROWPAT tells us above (as have many others on this message board) that changing only BPM can significantly induce a higher AHI. Where's your rationale in ignoring BPM changes' adverse effects on respiration and instead calling BPM setting a "comfort only" parameter?

And you call a rise time of 5 seconds with a spontaneous BPM of 14 a "comfort only" effect? Seriously? Let's see... with a spontaneous I:E ratio of 1:1 while breathing @14 BPM, human inhalation takes 2.14 seconds. And you're advocating that a rise time setting that takes .5 seconds to reach peak IPAP pressure for an inhalation cycle that lasts only 2.14 seconds is a darn good "comfort only" measure?

Better yet, take a common spontaneous-breathing ratio of 1:2 (I:E) @ CROWPAT's spontaneous 14 BPM. In this highly common-ratio, each human inhalation cycle takes 1.43 seconds instead. And you're telling CROWPAT an IPAP ascent slope that takes a whopping .5 seconds to deliver IPAP in the confines of that 1.43 second inhalation cycle makes sense---- because rise time is only a "comfort setting"? (edited to reflect 0.5s rise times instead of 5s at rt=5---please see post below).
CROWPAT wrote: Banned, I am really happy that you viewed and responded. Your opinions always make sense to me. My RT is at 5 right now - it just feels better to me. Tonight I will try your BPM and T(i) recommendations..
No offense to you or Banned. But it's threads with rotten advice like this that make perfectly good sense to non-technical readers that probably scare the hell out of the medical community who read along. At the very least, that kind of advice lends patient message boards like ours low credibility for illogically dial-winging complicated machines like yours.
CROWPAT wrote:Banned...Your opinions always make sense to me.
I won't blame you for not knowing any better. But that's one very unsettling quote IMHO.

My apologies for the bluntness. Good luck, CROWPAT. My apologies, Banned.
Last edited by -SWS on Tue Nov 24, 2009 10:18 pm, edited 1 time in total.

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by Banned » Tue Nov 24, 2009 10:17 pm

-SWS wrote:My apologies, Banned.
No apologies necessary, SWS. I totally agree with some of what you said. We can add a disclaimer for non-technical readers and the medical community that says do not try this at home. Actually it was the sleep medicine community that scared the hell out of me, hence the surname, Banned.

I (like you) do not think that BPM is the issue for this gentleman not reaching 0 AHi. However, I believe everyone with a manual back-uo rate machine should know the basics of setting there own BPM parameters, if they are thus inclined. Obviously, not setting BPM parameters properly will lead to AHi . My point (and I don't think the medical community would necessarily disagree) is that once BPM parameters are set properly for the individual, the act of breathing is a comfort setting. Differentiated from EPAP and IPAP which are sleep therapy settings.

Banned
AVAPS: PC AVAPS, EPAP 15, IPAP Min 19, IPAP Max 25, Vt 520ml, BPM 10, Ti 1.8sec, RT 2 (Garage)
BiPAP Auto SV: EPAP 9, IPAP Min 14, IPAP Max 25, BPM 10, Ti 2sec, RT 2 (Travel Machine)
VPAP Adapt SV: EEP 10.4, Min PS 4.4 (Every Day)
Mask: Quattro

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by -SWS » Tue Nov 24, 2009 10:38 pm

Banned, I just had to edit a typo correction into the rise time calculations above---since rt=0 through rt=5 reflect tenths of a second. However, the point is that aside from rise time impacting patient comfort, rise time also impacts tidal volume for any given IPAP/EPAP pair of values.
Results:

Rise Time

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

V_{T} 404.2 400.5 399.9 398.8 400.1 393.5 391.4 386.9

(S.D.) (0.3) (1.1) (0.4) (0.4) (0.4) (0.2) (0. (0.2)

Flow 0.231 0.226 0.235 0.221 0.222 0.203 0.208 0.186

(S.D.)(.001) (.010) (.011) (.005) (.004) (.004) (.002) (.010)

Conclusions: The study data suggest that longer rise time values produce smaller patient V_{t}S at a given IPAP/EPAP setting.
http://www.rcjournal.com/abstracts/1996/?id=A00001265

And neuromuscular effort required or Work of Breathing (WOB) is actually increased when a comfortable but lengthy rise time is selected :
WOB in Joules / L at: PRT 0 PRT 0.2 PRT 0.4 PRT 0.6
PS 10 (VT = 300) 0.04 0.08 0.08 0.13
PS 30 0.02 0.03 0.07 0.19?
PS 10 (VT = 600) 0.12 0.24 0.33 0.42
PS 30 0.04 0.09 0.13 0.16

Conclusion: PRT increases WOB at low level PS and high VT demand or when PRT markedly increases TI/TTOT beyond patient demand.
http://www.rcjournal.com/abstracts/1999/?id=A00000497 Above perceived comfort and alleviation of required respiratory muscular-effort are two diametrically opposed objectives for rise time.

So rise time is really more than just a comfort feature. It's a clearly a ventilatory parameter as well.


Also, I'd like to reintroduce those physiologic contraindication factors that can make arbitrary SV pressure adjustments potentially risky:
Patients without a spontaneous respiratory drive
• Existing respiratory failure (failure to treat; risk of increased work of breathing due either to incomplete reversal of
upper airway obstruction or to breathing at high lung volume, leading to worsening respiratory failure)
• Pneumothorax or pneumomediastinum
• Emphysematous bullae or a past history of pneumothorax (risk of pneumothorax)
• Acute decompensated cardiac failure or hypotension, particularly if associated with intravascular volume depletion
(risk of further hypotension or reduction in cardiac output)
• Massive epistaxis or previous history of massive epistaxis (risk of recurrence)
• Pneumoencephalus, recent trauma or surgery (e.g., pituitary or nasal) that may have produced cranio-
nasopharyngeal fistula (risk of entry of air or other material into the cranial cavity)
8 Acute sinusitis, otitis media, or perforated ear drum
• Acute or unstable cardiac failure
• Nocturnal or resting angina (risk of infarction or arrhythmias)
• Unstable arrhythmias
• Severely obtunded or heavily sedated patients
• At risk for aspiration of gastric contents
• Impaired ability to clear secretions
If patients are dehydrated or volume depleted, or have persistent atrial fibrillation, their cardiac filling pressures may be
low. In these cases, as with any CPAP or ventilatory support, use of the device may lead to a dangerous reduction in cardiac
output. The device should not be used in patients who are dehydrated or volume depleted, and should be used with extreme
care in patients with atrial fibrillation.
The cardiac factors in particular---either diagnosed or even occult--- can be adversely affected by arbitrary ASV pressure adjustments. The point is that caution is always in order, and because you have never personally heard of anyone suffering adverse physical affects from arbitrary ASV pressure experiments is not at all to say you are aware of actuarial numbers.

With that said, I acknowledge that patients are routinely left with adverse machine settings by their clinicians, and given the instructions to report in for a follow-up a year later. Or worse yet, we get set-it-and-forget-it patients who are never told to report back in---despite bad machine settings/data. An absolute patient dilemma IMHO.
Last edited by -SWS on Tue Nov 24, 2009 10:53 pm, edited 1 time in total.

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by Banned » Tue Nov 24, 2009 10:53 pm

-SWS wrote:The cardiac factors in particular---either diagnosed or occult--- can be adversely affected by arbitrary ASV pressure adjustments. The point is that caution is always in order, and because you have never personally heard of anyone suffering adverse physical affects from arbitrary ASV pressure experiments is not at all to say you are aware of actuarial numbers.
But, suppose arbitrary ASV pressure adjustments result in 0 AHi. Are cardio or adverse physical affects increased?

I love you, man!

Banned
AVAPS: PC AVAPS, EPAP 15, IPAP Min 19, IPAP Max 25, Vt 520ml, BPM 10, Ti 1.8sec, RT 2 (Garage)
BiPAP Auto SV: EPAP 9, IPAP Min 14, IPAP Max 25, BPM 10, Ti 2sec, RT 2 (Travel Machine)
VPAP Adapt SV: EEP 10.4, Min PS 4.4 (Every Day)
Mask: Quattro

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by -SWS » Tue Nov 24, 2009 11:09 pm

Banned wrote:
-SWS wrote:The cardiac factors in particular---either diagnosed or occult--- can be adversely affected by arbitrary ASV pressure adjustments. The point is that caution is always in order, and because you have never personally heard of anyone suffering adverse physical affects from arbitrary ASV pressure experiments is not at all to say you are aware of actuarial numbers.
But, suppose arbitrary ASV pressure adjustments result in 0 AHi. Are cardio or adverse physical affects increased?

I love you, man!

Banned
Well, if AHI represents apneas/hour and one apnea takes infinite hours... who in their right mind wants that AHI of 0? Hence the words of caution: proceed with great care.

But yeah... I agree with the objective of the far better 0 AHI scenario you have in mind. That is clearly better than some of the horrendous machine settings and AHI values that patients on these message boards routinely report in with. I don't blame anyone for methodically trying to save their own health and life given the clinical neglect and even incompetence that CPAP users routinely report into the message boards with. A veritable patient life-and-limb dilemma---one that's reported on all apnea message boards regularly...

In the meantime, the FDA is addressing this mess by cracking down on small things like humidifier and mask prescriptions. God forbid that a patient---who has already been granted a CPAP machine---should get their hands on a compliance-making humidifier or comfortable mask without going through a prescription gauntlet---one that clearly favors the status-quo brick-and-mortar DME business arrangements regarding traditional prescription hand offs.

The best solution IMHO is to search for a good doctor or clinician to work with...

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by Banned » Tue Nov 24, 2009 11:32 pm

-SWS wrote:Banned, I just had to edit a typo correction into the rise time calculations above---since rt=0 through rt=5 reflect tenths of a second. However, the point is that aside from rise time impacting patient comfort, rise time also impacts tidal volume for any given IPAP/EPAP pair of values.
Results:

Rise Time
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Conclusions: The study data suggest that longer rise time values produce smaller patient V_{t}S at a given IPAP/EPAP setting.
http://www.rcjournal.com/abstracts/1996/?id=A00001265

And neuromuscular effort required or Work of Breathing (WOB) is actually increased when a comfortable but lengthy rise time is selected :
The point is that caution is al[/quote]

Interesting stuff, SWS,

Our guy says he likes a Rise Time (RT)\ of 5 millisec which results in his seemingly 'normal' tidal Volume of 545. I'm sure he doesn't have a clue whether he is 'obstructive' or 'restrictive'. I used to think I was restrictive and used to use a RT of 5 millisec. Then I read one of your posts, perhaps a year ago and decided I was 'Obstructive'. Talk about dial-wingin.. I changed my RT to 2 millisec (obstructive) and have never looked back. Thanks for that bit of arbitrary ASV knowledge!

Banned
AVAPS: PC AVAPS, EPAP 15, IPAP Min 19, IPAP Max 25, Vt 520ml, BPM 10, Ti 1.8sec, RT 2 (Garage)
BiPAP Auto SV: EPAP 9, IPAP Min 14, IPAP Max 25, BPM 10, Ti 2sec, RT 2 (Travel Machine)
VPAP Adapt SV: EEP 10.4, Min PS 4.4 (Every Day)
Mask: Quattro

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Re: BIPAP AUTO-SV SETTINGS HELP

Post by -SWS » Wed Nov 25, 2009 12:31 pm

Banned, I'm so glad you got your login working...

Again, CROWPAT, good luck with your experiments! Please be careful.