VPAP user: Some unusual efficacy results

[McSleepy]

After unsuccessfully trying a Respironics PR System One for a couple of weeks, I was given a ResMed VPAP Auto 25. The initial settings were EPAP 7 and IPAP 15 (I had a history of using a Respironics BiPAP Pro at EPAP 10, w/BiFlex of -3, and IPAP of 17) and over a few days I had an AHI of around 35 with an AI of around 25. Yesterday, after seeing the DME, the EPAP was changed to 10 (and the trigger sensitivity was increased to "high"). Last night I had an AHI of 0.4 and an AI of 0.0! Now, I just emailed the DME and I'd like to throw this quickly here before he calls me, without getting into details: all is not good. Not counting that I don't feel comfortable with those settings (I'm used to the nice drop from the BiFlex) and the aerophagia, some of the other numbers are disturbing (which they were not before yesterday). The tidal volume, as reported by the "Efficacy" menu of the Auto 25, is between 240 and 820 mL/min (the latter is closer to my normal TV; yes, my vital capacity is huge - nearly 7L), the respiratory rate is 16-42 (!), and the minute ventilation is 7.3 - 14.8 L (!) Oh, and there are no leaks (the reported number is 0.1L/s). What do you think about that? I think the DME only cares about AHI and I couldn't give him any statistics if he said this is all good and I should stay with those numbers. What do you, guys, measure normally?
McSleepy

[roster]

McSleepy, Let me suggest you enter "edit this message" and change the subject to "VPAP User Needs Help". VPAP users and experts are a minority on the forum and this will help get their attention more quickly. Good luck.

[robysue]

McSleepy,

I won't comment on most of the numbers 'cause I don't know enough about your situation. i'm in the process of going from the S9 Auto to the PR S1 BiPAP Auto so I'm also getting used to a new set of data numbers though. And I understand enough about the leak stuff to maybe make a comment on it.

Does the ResMed VPAP Auto 25 have a mask setting like the S9 does? If so, then the intentional mask flow is automatically subtracted off of the leak data before it's reported in ResScan. And that would explain why your leak data is at or near 0 L/sec.

As to how and why the other data would look so wildly different with the new settings and why there's such a wide range in some of the data's values, I haven't the foggiest idea. I would report the aerophagia problems to your sleep doctor as well as the DME. That could easily be explained by the increase in the EPAP/IPAP settings in my opinion.

You also say you're missing the Bi-Flex from the PR S1 BiPAP. Have you turned on EPR on the VPAP? If you try EPR with setting equal to 3, it might give you something similar to what you had with the Bi-Flex set to 3. But it won't be exactly the same because the EPR = 3 will be "exhale relief pressure" at a fixed -3cm---in other words at the beginning of each exhalation phase, the pressure will temporarily be reduced to EPAP-3cm and then be increased back up to EPAP by half-way through the exhalation phase of the breath. Pressure will be increased up to IPAP once you start your inhale and the Ti setting controls how fast the pressure goes from EPAP to IPAP if I recall correctly.

[McSleepy]

Does the ResMed VPAP Auto 25 have a mask setting like the S9 does? If so, then the intentional mask flow is automatically subtracted off of the leak data before it's reported in ResScan. And that would explain why your leak data is at or near 0 L/sec.

Yes, it does, and it is set to “Swift”, which is very similar to my Breeze (same size pillows). I have looked at waveforms before and the leak has always been very small – my modifications and stomach-sleeping style generally ensure a tight seal.

As to how and why the other data would look so wildly different with the new settings and why there's such a wide range in some of the data's values, I haven't the foggiest idea. I would report the aerophagia problems to your sleep doctor as well as the DME. That could easily be explained by the increase in the EPAP/IPAP settings in my opinion.

I have reported the aerophagia in that email. But it’s not that unusual – I’ve had that periodically: when you’re at 15cm, you can expect it to happen once in a while. I’m just trying to tell me DME that with the EPAP at a lower setting I didn’t have it, even though the IPAP has remained the same.

You also say you're missing the Bi-Flex from the PR S1 BiPAP. Have you turned on EPR on the VPAP? If you try EPR with setting equal to 3, it might give you something similar to what you had with the Bi-Flex set to 3. But it won't be exactly the same because the EPR = 3 will be "exhale relief pressure" at a fixed -3cm---in other words at the beginning of each exhalation phase, the pressure will temporarily be reduced to EPAP-3cm and then be increased back up to EPAP by half-way through the exhalation phase of the breath. Pressure will be increased up to IPAP once you start your inhale and the Ti setting controls how fast the pressure goes from EPAP to IPAP if I recall correctly.

Unfortunately, the EPR is only available in constant-pressure mode on the Auto 25, not in VPAP. We have been playing with the Ti and trigger, I’d like to try the cycle and rise time, but for now, it’s very inconvenient as the DME is 15 miles away and, as I said, I don’t want to hurt his feelings by changing it myself. Although I have asked him in that email to call me and I will bring up the Holidays as a reason for him to allow me to change my own settings (telling him that I already know how, so he won’t be letting the cat out of the bag).

And, I do realize that this is results from only one night, but my points is that I should probably try to lower EPAP by 1 cm based on those results. I can always go back to 10cm.
Mc Sleepy

[robysue]

Does the ResMed VPAP Auto 25 have a mask setting like the S9 does? If so, then the intentional mask flow is automatically subtracted off of the leak data before it's reported in ResScan. And that would explain why your leak data is at or near 0 L/sec.

Yes, it does, and it is set to “Swift”, which is very similar to my Breeze (same size pillows). I have looked at waveforms before and the leak has always been very small – my modifications and stomach-sleeping style generally ensure a tight seal.

Well, that completely explains your leak rate number being so close to 0 then. On the PR, I bet that if you looked at your leak rate in Encore Viewer, it was most likely a pretty flat line close to the expected intentional mask flow for your pressure setting. Since the VPAP is now subtracting that intentional mask flow off of the leak rate data, you'd expect your leak rate to now be right around 0.0 L/sec.

As to how and why the other data would look so wildly different with the new settings and why there's such a wide range in some of the data's values, I haven't the foggiest idea. I would report the aerophagia problems to your sleep doctor as well as the DME. That could easily be explained by the increase in the EPAP/IPAP settings in my opinion.

I have reported the aerophagia in that email. But it’s not that unusual – I’ve had that periodically: when you’re at 15cm, you can expect it to happen once in a while. I’m just trying to tell me DME that with the EPAP at a lower setting I didn’t have it, even though the IPAP has remained the same.

This makes sense to my not very medical understanding of how CPAP/bi-level machines induce aerophagia. I've recently been switched to BiPAP primarily because of aerophagia issues with CPAP at rather lowish pressure levels myself. As I understand it, the exhalation phase of each breath lasts longer than the inhalation phase. So an increase (particularly of 3 cm) in EPAP is more likely to affect aerophagia than a similar increase in pressure in IPAP.

Unfortunately, the EPR is only available in constant-pressure mode on the Auto 25, not in VPAP.

I didn't realize this. Sorry about that. This is truly a limitation of the VPAP isn't it?

Would using a ramp to get to sleep help or hurt in your opinion? And did the DME give you the option of turning the ramp on?

[McSleepy]

I didn't realize this. Sorry about that. This is truly a limitation of the VPAP isn't it?

Would using a ramp to get to sleep help or hurt in your opinion? And did the DME give you the option of turning the ramp on?

Thank you for your responses, robysue, I really appreciate your effort. Yes, it's a bummer how this advanced machine does not have a simple expiratory relief setting available under the advanced modes!
As for the ramp, I don't think it would help since the problem is not so much to fall asleep (in fact, it took me about 5 minutes to fall asleep yesterday with it), but the hyperventilation and the increased aerophagia that occur through the night. I will definitely work with the DME on all that. By the way, he still hasn't called; if he doesn't call or respond to my email, and is thus not available through the Holiday break, I think that might be "sufficient grounds" for me to go ahead and change it myself .
McSleepy

[McSleepy]

I got my reader today and was able to download the data. It had all summary data from the beginning and detailed data from yesterday, only (the day in question). Here are the graphs:



You can see the two major increases in respiratory rate, the lack of leaks at that time, but similar minute volume as the rest of the night. That seems to indicate that I am not hyperventilating (more than the 11-12 L/min that is twice as normal but still considered not pathological), after all, but rather that the breathing becomes really shallow (at over 40 BPM). I think that is a clear indication that the EPAP could be lowered a bit. Isn't it?

McSleepy.

[Diplomacy]

You can post a vpap machine at CPAP.com!

[McSleepy]

An update to this. A few weeks later, the problem appears resolved. What it took was some tweaks to the various settings the Auto 25 offers. The most important ones seem to be the trigger sensitivity and the minimum inspiratory time. I set the former to "very high", which makes it so that the machine goes to IPAP upon the slightest thought of inhalation, and the latter - it sustains the IPAP for at least the set time (in my case, 1.6 seconds). The first one helped me initiate inhalation easily, while the second prevented the premature exhalation, which would otherwise cause high respiratory rate. Now all my measurements are in check (although a respiratory rate of around 20 BPM still seems a little high) and my AHI is well under 1.0.
McSleepy

[BusyLyn]

According to my First Responder course materials (and an internet search), normal adult respiration rate is 12-20 breaths per minute. I wouldn't fixate on your respiration rate, especially as your results are good. We're all different, that's why there's a range!

[McSleepy]

Another update: I just had an overnight high-resolution pulse oximetry test at home and last night the doctor called and told me the results were outstanding - between 90 and 99%, with basal SpO2 of 95%. Given that I'm at 5000ft elevation, I tend to agree with the assessment of my sleep doctor.
There seems to be no doubt that my CPAP treatment is working, the only question is, should I be worried about having to have it? That is, should I make significant efforts trying to find ways to change what I have now, given that I'm otherwise healthy, not much overweight, with clear(er) airways? One reason to have such thoughts is that my parameters are not quite common: bi-level, with a relatively high pressure support (9/14), high sensitivity to sleeping position and mask choice (the only one that works is a heavily modified version of a Breeze) because of my inability to sleep in anything other than a prone sleeping position, etc. The DME kept insisting that a pressure support over 2cm H2) is not normal for an otherwise healthy person, that I should be looking at lowering the IPAP, and that I should be using new masks, and stuff like that. The sleep doctor at one time suggested I should try going to constant pressure, and when I replied that I couldn't even fall asleep with it, he suggested I used hypnotic sedative (!) to force me to fall asleep until my brain got used to it... Thoughts like that.
McSleepy

[roster]

There seems to be no doubt that my CPAP treatment is working, the only question is, should I be worried about having to have it? That is, should I make significant efforts trying to find ways to change what I have now, given that I'm otherwise healthy, not much overweight, with clear(er) airways? One reason to have such thoughts is that my parameters are not quite common: bi-level, with a relatively high pressure support (9/14), high sensitivity to sleeping position and mask choice (the only one that works is a heavily modified version of a Breeze) because of my inability to sleep in anything other than a prone sleeping position, etc. McSleepy

What options to CPAP are you considering?

I recommend an evaluation by a good and conservative ENT including a fiber-optic nasolaryngoscopy. If the ENT recommends surgery you need to do some heavy research including opinions here before making a decision.

Depending on your age, an evaluation by an orthodontist may also be appropriate.

[McSleepy]

What options to CPAP are you considering?
I recommend an evaluation by a good and conservative ENT including a fiber-optic nasolaryngoscopy. If the ENT recommends surgery you need to do some heavy research including opinions here before making a decision.
Depending on your age, an evaluation by an orthodontist may also be appropriate.

I'm not really seriously considering any alternatives right now. I had just seen an ENT (viewtopic/t58445/viewtopic.php?f=1&t=59128&p=556268) and my nose is clear now. The ENT (who is actually a renown plastic surgeon) had initially suggested the works: septoplasty, UPPP, but he never insisted, and the nose is clear now, after that procedure I had. As for the soft tissue - I have heard horrible stories about UPPP, and not because of bad surgeons, it's just difficult to predict how well the procedure would be tolerated by the patient. Not to mention, I really hate general surgery. But the bigger issue is during all of my sleep studies, which might not have valid results as I wasn't able to even fully fall asleep (because of my inability to sleep under the conditions they had me under), all of the apneas detected were of the central kind, none were obstructive. Yet, no other health problems were discovered.
One of the options the last sleep doctor suggested was continuously taking hypnotic sedatives to knock me out and "let the brain get used to constant pressure". I think that is crazy. The other option was a dental appliance but because of what I just described I don't think that's going to do anything, and even if it could, it certainly would not be an easy transition. How do you go from years of fine-tuned bi-level CPAP to normal aspiration? Anyway, I appreciate your concern but at this time I don't even know what to be thinking right now. The good news is I'm doing great on CPAP and I can stay on it indefinitely, giving me time to think.
McSleepy

[roster]

The good news is I'm doing great on CPAP and I can stay on it indefinitely, giving me time to think.
McSleepy

Excellent!

[secret agent girl]

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