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Strange waveform?
#1
Question 
I noticed the airflow trace from last night looked different from usual. Is this type of waveform unusual? Does it signify anything?

As always, thanks to everybody on here for your help.


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DeepBreathing
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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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#2
Ok, that _is_ weird.

Firstly, I'm glad that I'm not the only one who has issues with their SleepyHead plots and axis labeling. With your mask pressure as labeled, you are getting up to 35 cmH2O pressure at the mask, which is significantly above the capabilities of your machine.

One thing I did notice was that your breathing rate is unusually slow in those plots - something like ~10 breaths per minute. I wonder if what is being shown here is a sequence whereby you are solidly in Central Apnea (ie. you are not breathing on your own) and the machine is essentially acting as a ventilator. Hence the increased flow rate when the pressure is increased as the air is pushed into your lungs, and the sharply negative flow rate when the pressure is reduced as your resting state pushes the air (rapidly!) out of your lungs.
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#3
The SleepyHead software is not fully compatible (yet) with PR BiPAP autoSV Advanced machines. The weird scales on the vertical axes may be due to a bug that affects those machines. JediMark (aka Mark Watkins), the author of SleepyHead has said that he does not yet have enough data from ASV machines to fully debug the SleepyHead problems that affect the PR BiPAP ASV users who try to use SH. If you're willing to share your data, you might want to register over there and contact JediMark through a PM.
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#4
Graph axis labeling problems are not limited to BiPAP machines. I occasionally have problems with my PRS1 60 Series Pro and PRS1 60 Series Auto machine data. Manually setting graph axis limits, then quitting and re-starting seems to work around most of them.
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#5
(10-28-2013, 02:48 PM)robysue Wrote: If you're willing to share your data, you might want to register over there and contact JediMark through a PM.
You can contact Mark here too Coffee
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#6
(10-28-2013, 02:25 PM)RonWessels Wrote: One thing I did notice was that your breathing rate is unusually slow in those plots - something like ~10 breaths per minute. I wonder if what is being shown here is a sequence whereby you are solidly in Central Apnea (ie. you are not breathing on your own) and the machine is essentially acting as a ventilator. Hence the increased flow rate when the pressure is increased as the air is pushed into your lungs, and the sharply negative flow rate when the pressure is reduced as your resting state pushes the air (rapidly!) out of your lungs.

Thanks Ron - it was the shape of the waveform that bothered me more than the scale error. My sleep study and subsequent treatment on an APAP machine showed lots of centrals, which have now almost disappeared. It seems the ASV machine is doing a good job for me.
(10-28-2013, 02:48 PM)robysue Wrote: The SleepyHead software is not fully compatible (yet) with PR BiPAP autoSV Advanced machines. The weird scales on the vertical axes may be due to a bug that affects those machines. JediMark (aka Mark Watkins), the author of SleepyHead has said that he does not yet have enough data from ASV machines to fully debug the SleepyHead problems that affect the PR BiPAP ASV users who try to use SH. If you're willing to share your data, you might want to register over there and contact JediMark through a PM.

Happy to share, but I've only got this machine on loan for a few more days until my Resmed S9 VPAP arrives.
DeepBreathing
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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
Yeah, that is a software bug - we've seen it over here too in the clinics, and some clinics prefer using both the proprietary software for each manufacturer and freeware stuff, just to compare data, but it doesn't always work, as in this case.
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#8
Thanks for all the help - I learn more every time I come to this site.

As a follow-up question, since I've been on the Bipap machine I see lots of periods where the machine is recording a pressure pulse on every single breath. Following on from Ron's comments above, is this an indication of the machine controlling my breathing to prevent centrals? On the APAP machine I had previously, I saw big clusters of centrals which now don't occur any more.


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DeepBreathing
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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
(10-30-2013, 12:00 AM)DeepBreathing Wrote: As a follow-up question, since I've been on the Bipap machine I see lots of periods where the machine is recording a pressure pulse on every single breath. Following on from Ron's comments above, is this an indication of the machine controlling my breathing to prevent centrals? On the APAP machine I had previously, I saw big clusters of centrals which now don't occur any more.
First a clarifiation: The machine you are using is not just a plain old BiPAP (like my machine). You are using a BiPAP ASV Advanced machine. A plain old BiPAP is not designed to treat CSA or CompSA because a plain old BiPAP does NOT have the ASV algorithm. And it's the ASV algorithm that treats central apneas.

Those "pressure pulses" you are noticing are NOT the "pressure pulses" the System One APAP uses to decide whether an apnea is a CA or an OA. The APAP's PPs are little blips of an increase of about 2cm pressure and the machine uses what happens to the back pressure to figure out if the airway is blocked or not. And also note that the APAP you were using had no way of treating your CAs: When clusters of CAs were happening, it was not "smart" enough to step in and start triggering you to inhale because its auto algorithm does not have the ASV algorithm that your current machine has.

The "pressure pulse" you are seeing in your ASV's data are machine triggered inhalations. Look at the mask pressure graph: For each "pressure pulse" the machine increased the pressure from your EPAP setting of 6 cm up to an IPAP = 15cm. Any chance your max PS = 9? Those EPAP - to - HIGH IPAP pressures are exactly how your BiPAP ASV machine is designed to treat your central apneas: During the stretch of breathing you've posted, the machine is not happy with what it is detecting as your efforts to breath on your own. Hence it is triggering inhalations---encouraging you to take an inhalation---by bumping that IPAP up so high.

And hence, your BiPAP ASV Advanced is preventing the CAs from happening. And that's why you're not getting the big gobs of CAs that you were seeing on the APAP.
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#10
Robysue, thanks for the detailed explanation - it's much appreciated.

The therapist had been trying all sorts of strategies to get the auto machine to do the trick before trying the ASV, simply because they are so expensive here (and the cost of the machine is nearly all out of pocket). But with the results I'm seeing, and your explanation, it's confirmed that ASV is the way I have to go.
DeepBreathing
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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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