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Need help with Philips Respironics BiPAP AVAPS
#1
Need help with Philips Respironics BiPAP AVAPS
I am using the pressure control (PC) mode to treat nocturnal hypoventilation. My current settings are IPAP 18, EPAP 5, Inspiratory time 1.0 sec, Rise Time setting of 2, Backup rate of 12bpm, and Humidity level of 2.

My main issue is that I started with IPAP 16 and EPAP 5. My tidal volume was only 260mL/kg which is very low. AHI was very low - .5, all hypopneas. I'm not sure if PR differentiates obstructive versus central hypopneas. To raise the tidal volume, I increased IPAP to 17. AHI went to .7 after that. Last night at IPAP 18, my tidal volume is better at 330. But now my AHI shows as 1.3 - all hypopneas. It seems the increase in IPAP is increasing the hypopneas, although generally I understand raising IPAP should *decrease* hypopneas.

One thing I have noticed and played with is decreasing the inspiratory time. A while ago when I had the Ti set to 1.5 seconds, my AHI would shoot up to 10+ - all hypopneas. If I lowered the Ti to 1.2 seconds, the AHI cut in half at about 5. So now with a Ti of 1 second, the AHI is very low. Maybe the prolonged Ti causes flow limitations.

I have of course tried using the spontaneous/timed or s/t mode, but because of my restrictive lung disease the inhalations keep getting cut off and my breathing becomes out of sync all the time. Altering the rise time setting doesn't help either. If I make the rise time longer the machine actually doesn't even get to the full IPAP pressure when I inhale.

I have also tried enabling AVAPS as well, but I am not a fan of the IPAP adjusting all the time - it's hard to fall asleep and it sometimes wakes me up when the pressure is very high.
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#2
RE: Need help with Philips Respironics BiPAP AVAPS
Matt, what is the root cause of hypoventilation? I assume you meant Vt is 260 mL, not per kg. Normal is around 7 mL/kg or 500 mL for a 72 kg individual ideal weight. Have you tried Sleepyhead 1.1.0?
Sleeprider
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#3
RE: Need help with Philips Respironics BiPAP AVAPS
(11-06-2018, 11:27 AM)Sleeprider Wrote: Matt, what is the root cause of hypoventilation?  I assume you meant Vt is 260 mL, not per kg. Normal is around 7 mL/kg or 500 mL for a 72 kg individual ideal weight.  Have you tried Sleepyhead 1.1.0?

Hey thanks for the reply. I have Kyphoscoliosis, a chest wall disorder, which is considered a restrictive lung disease due to the inability for my lungs to expand properly because of the deformed chest wall.

Yes correct - measured Vt was 260 mL. I am male and weigh about 110lbs and am 5 feet tall. I stopped growing after I was 13 because I had my spine fused to prevent further curvature. Unfortunately I had surgery before they started using the VEPTR rods that allow you to continue growing while the spine is also stabilized.

Off the top of my head I am not sure what Sleepyhead version I have, but I did check for updates within the last month and none were available.


I do know that the machine is helping statistic wise. I am able to increase my Vt and decrease my respiratory rate so it's helping with the work of breathing.
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#4
RE: Need help with Philips Respironics BiPAP AVAPS
Thanks for filling in some health details, it helps make sense of some things. Here is a link to the most recent Sleepyhead Beta that may work with your machine version 1.1.0 http://www.apneaboard.com/forums/Thread-...STING-Beta

Your discussion of altering the Ti settings is interesting, and presents a dilemma, in that with a longer Ti of 1.5 seconds, you experience hypopnea. I assume this is due to the inability to exhale the volume of air before the machine times a new inspiration, so you essentially try packing more air into a lung that is not ready to receive a full breath. With shorter Ti at 1.2 seconds, hypopnea is not present, but you feel inspiration time is too short and cut-off using ST mode. What breath rate and rise time did you set?
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#5
RE: Need help with Philips Respironics BiPAP AVAPS
In PC mode the inspiratory time is constant - so for all breaths. At Ti 1.2 seconds I get an AHI of about 5 - all hypopneas. At 1.0 seconds my AHI is now 1.3, but can get as low as .6 or so (depending on the IPAP level, as discussed).

When I trialed the ST mode, I set the backup rate to 12bpm and the backup Ti to 1.5 seconds. Doing this I basically have no AHI. However, inspiration time is severely cut off in the ST mode. Sometimes I barely just start breathing in and it will sharply cut the breath off and cycle to EPAP or try to start another inhalation. This is highly uncomfortable and my breathing gets very out of sync and I start fighting with the machine. It's very hard to fall asleep this way.

My rise time has been setting 2 (300ms) or 3 (400ms). I do notice that with setting 3 or longer, I am unable to reach the full set IPAP pressure. So at rise time setting 3, with IPAP set to 18, I may only average in a night of sleep an IPAP of 16.8 or so (for example). With a rise time setting of 2, I am able to maintain the set IPAP pressure throughout the night without any under or over shoot of pressure. So it seems to match up well.

I was planning to try a Ti of .9 seconds tonight and seeing how that goes, since the trend seems to fit. I do worry about being basically forced to take the quicker breaths with the fixed Ti, but it does seem to match the way I breathe.

I have used a ResMed machine before, which has some more customization with the Ti Min and Max, but the statistics are better with me on the Respironics...with the ResMed my respiratory rate is very high for whatever reason. I think because the Respironics automatically adjusts the trigger and cycle with the digital auto-trak, that for whatever reason that works better for me. Or the ResMed is set wrong for me.
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#6
RE: Need help with Philips Respironics BiPAP AVAPS
Good information and description of the problem. I think the first thing to try is set the rise time at 200 ms. This should allow you to complete inspiration faster and get a more complete breath before the machine cycles. A combination of lower respiration rate, higher inspiration time and shorter rise time seems like it might deliver a more comfortable experience. I'm pretty sure you need ST mode, but it might work better at a lower respiration backup rate. If you want to target 12 bpm, you should set the backup at 10 to promote as much spontaneous trigger and cycle as possible.

I don't know how long you have had the PRS1 1060, but next time you qualify for replacement, the Resmed Aircurve ST-A may be a better fit. It uses an iVAPS algorithm to target tidal volume with dynamic pressure support, rather than mechanical timing, rise time and fixed pressure support. Worth a try if you have the chance.
Sleeprider
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#7
RE: Need help with Philips Respironics BiPAP AVAPS
I own both the BiPAP AVAPS and a ResMed AirCurve 10 ST-A actually. The iVAPS mode is not comfortable to me. It uses servo-ventilation so the IPAP can go from low to high in mere seconds just like an ASV. I've attempted to adjust the min PS and follow the median IPAP, and that still doesn't seem to help avoid the pressure swings. Maybe they could figure it out in a lab setting but I have had really bad experiences in sleep labs. I'm supposed to meet with a respiratory therapist this week, but I honestly have no idea how that is going to help.

At pressures of 18/5, my median respiratory rate is 19bpm, so not anywhere near the backup rate of 12bpm. The lowest RR recorded was 14bpm. The max RR was 23, and the 95% was 21.

I can try the S/T mode with a faster rise time - that is a good idea to try.

Clearly if Ti 1.5 seconds in PC mode is AHI of 10, 1.2 seconds is 5, 1.0 seconds is < 1.5, etc., it means that the longer mandatory inspiratory times are not a good thing for me. If I'm breathing fast, that means I want a quick full inhale, so the longer fixed Ti when sleeping fights against this pattern, not allowing me to exhale fully. But in PC mode, I also run the risk of a fixed shorter Ti, so in cases where I do want to breathe in longer the machine won't let me.
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#8
RE: Need help with Philips Respironics BiPAP AVAPS
Do you know the approximate inhale / exhale times when you are comfortable. You indicated a median respiratory rate of 19/minute, so that leaves 3.15 seconds per breath. If you use half that for inspiration at 1.5 seconds, it makes sense, you won't likely complete exhale before the next breath triggers. As you know, at 12 bpm, each breath has 5 seconds, so Ti of 1.5 should normally leave plenty of time (3.5) for expiration to complete.

I appreciate the input on the iVAPS, as I have no personal experience with it, and it is unusual to find forum members using the technology. When you used it, what were the settings for Va target, PS min, PS max and iBR?

Your efforts to optimize therapy and improve results is impressive, and I'll offer, you know more about these machines and how to use them than I do, but thanks for giving us a window to your efforts to make this more comfortable.
Sleeprider
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____________________________________________
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#9
RE: Need help with Philips Respironics BiPAP AVAPS
The issue it seems is that my Ti when awake, and my Ti while sleeping, is vastly different. For example, in using the ResMed machine, on the screen it will show a spontaneous inspiratory time of maybe 1.7 seconds and a respiratory rate of 15bpm. But, when I fall asleep, my Ti will drop to the minimum of say .8 seconds and then my respiratory rate increases somewhat. I can of course increase the Ti min to match the awake values, but then when I fall asleep my respiratory rate nearly doubles in what I assume is me fighting against the machine to exhale and then my I:E ratios become almost inverted where I barely have any time to exhale, and spend longer in inspiration than exhalation. I have tinkered with Ti min and Max, rise time, Cycle and Trigger sensitivity, but it's clearly not matching up with my breathing pattern. If I keep the Ti min high on the ResMed, I get respiratory rates in the 30's and 40's while asleep, and as a result my Minute Ventilation becomes dangerously high at like 8 or 9. A big problem is that I am asleep during all this so I cannot tinker in this way in an intelligent fashion.

For iVAPS I tried using the titration defaults, and also the 'learned targets' mode. I started with PS Min 4, PS Max 20, iBR of 15bpm (any higher and for whatever reason it kept getting out of sync with me), and a target Va that matched a target tidal volume of 6mL/Kg. Then per the guide, I raised the target Va each night as to increase the Mv, and improve oxygen saturation. I also realize my iBR isn't technically accurate, because there is a large discrepancy between my RR while awake, and my RR while sleeping.

I wasn't sure whether to use my measured height, or a slightly taller height that allows for the fact that my spine is curved and prevents me from standing up straight. So I did try plugging in the different heights to see if it makes a difference. This helps the machine known that you have additional dead space that it otherwise would not account for.
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#10
RE: Need help with Philips Respironics BiPAP AVAPS
Your PS is fixed at 13 cm with S or ST mode, so I don't follow the logic of a range of 4-20 on iVAPS. I think closing that range in on what you know to work might avoid a lot of fluctuation.

For now, just try the shorter rise time. If we try to do too much at once it will just get confusing, and you have a lot to consider in these posts already.
Sleeprider
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www.ApneaBoard.com

____________________________________________
Download OSCAR Software
Optimizing Therapy
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How To Attach Images And Files to your posts
How To Deal With Equipment Supplier
Mask Primer
Beginner's Guide to Sleepyhead

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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