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Bi-Level, S, ST, ASV??
#91
RE: Bi-Level, S, ST, ASV??
iVAPS is what the ST-A device does, I believe... I need to learn more about that... and more importantly how that differs from AVS... and what specifically about AVS causes issues for people with heart failure (or at least the study showed)... which I assume is not part of iVAPS... from brief reading, it seems that iVAPS and AVS both vary rates on the fly to adjust to the user... but I need to find a good, detailed description and comparison of Bilevel w/ BR, IVAPS, AVS.

Have you ever seen any info or posts on here about length of treated apneas and O2?  I am trying to understand how an apnea over 30 seconds would not cause a person to lose consciousness during sleep.  Most apneas occur after exhale, with lungs empty, and it is not like taking a deep breath and holding it, where you can go for more than a minute and be fine.  With lungs empty, after even 10 seconds you need air.  I wonder if it has to do with the CPAP air pressure... even if no respiration is taking place, does the CPAP pressure cause enough new oxygen to migrate into the lungs to keep O2 levels up even during long treated centrals?  I can't find any info on this anywhere...  or may be even when you feel starved for oxygen, your body's reserve is still keeping blood O2 level up.
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#92
RE: Bi-Level, S, ST, ASV??
What you first need to know about the ASV warning for individuals with low LVEF is that the SERVE-HF study was based on using older machines with fixed EPAP pressure and fixed minimum PS. and the study cohort was not titrated for efficacy. In addition, the study did not stipulate a minimum use for the machine (compliance). These were legacy machines with different algorithms than today's ASV auto and Auto SV which have auto-adjusting EPAP to keep pressure lower, and which allow a minimum PS of zero, with responsive adaptive pressure support to target minute vent or tidal volume. In many ways, the older ASV/SV was an adaptation of the comparatively dumb ST you are now using. A "reason" for the increased mortality in the cohort was not identified. The study was terminated based on a statistically significant increased risk of sudden cardiac death. The new ADVENT-HF study in progress is using modern ASV / SV machines titrated to for efficacy and monitored for minimum use. The study cohort is individuals with CHF and LVEF. So far, the study has shown a significant improvement in the patients using ASV over those using CPAP and bilevel ST, and no increased mortality. this study should complete in mid 2020, and will be published by 2021. Earlier in this thread, I mentioned that in 2-3 years, your doctor will have a different recommendation than today, and based on other errors by your doctor, I doubt he is following the studies.

iVAPS (Resmed) and AVAPS (Philips) Volume Assured Pressure Support is mostly targeted at patients with COPD, hypoventilation and neuromuscular thoracic disorders, while ASV is intended to treat central and complex apnea and obstructive apnea in patients with otherwise relatively healthy respiratory function. The iVAPS and AVAPS target the same patient subsets as the older ST technology, but use intelligent algorithms instead of fixed pressure support to maintain ventilation. VAPS machines can exceed the capability of ASV in that they have many more controls including a breath rate, and an aveolar volume rate setting that ASV lacks. The Resmed ASV is really only suitable for someone that maintains a normal respiratory rate and volume because it targets the patient's spontaneous RR and Vt from the previous 90 seconds. If that individual has insufficient respiration to start with, there is no way to cause an ASV to deliver an assured volume, as the iVAPS does. So when a more complex ventilation need is presented, particularly where a patient cannot maintain their rate and volume due to pulmonary disease or other respiratory disorder (as opposed to simple complex or central apnea), then the VAPS machines come into play. Put more directly, the ASV does not target a prescribed ventilation ad respiration rate, it instead targets targets the patient's own baseline minute vent and RR, which can result in a diminishing ventilation rate (Resmed), or it may have a targeted ventilation rate and targets the patient's tidal volume (Philips).

Here is a research summary released last year that explains AVAPS/iVAPS https://www.researchgate.net/publication...re_support
Sleeprider
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#93
RE: Bi-Level, S, ST, ASV??
(11-16-2019, 09:15 PM)jtech1 Wrote: I just read an nih article that states:

"some reports suggest that a brisk response (or shorter rise time) may have some inherent oscillatory behavior that may set the stage for “emergent” central apneas."

The ST unit defaults to "min" for rise time... which I assume is as fast as possible (but would be nice if they documented ms for min.. next lowest setting is 150 ms).  Do you know of any threads on here where people have discussed rise time?  Search did not turn up any.

Also, above you translated my words "timed insp" to "Ti min"... how do you know that?  Could it be Ti max?  Ti min is currently 0.3s, and going to 1.8 is a big jump... I assumed it meant Ti max should be 1.8.


I found the default rise time very uncomfortable so I set mine to a setting of 300ms it was much more comfortable
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#94
RE: Bi-Level, S, ST, ASV??
(11-17-2019, 01:37 PM)jaswilliams Wrote:
(11-16-2019, 09:15 PM)jtech1 Wrote: I just read an nih article that states:

"some reports suggest that a brisk response (or shorter rise time) may have some inherent oscillatory behavior that may set the stage for “emergent” central apneas."

The ST unit defaults to "min" for rise time... which I assume is as fast as possible (but would be nice if they documented ms for min.. next lowest setting is 150 ms).  Do you know of any threads on here where people have discussed rise time?  Search did not turn up any.

Also, above you translated my words "timed insp" to "Ti min"... how do you know that?  Could it be Ti max?  Ti min is currently 0.3s, and going to 1.8 is a big jump... I assumed it meant Ti max should be 1.8.


I found the default rise time very uncomfortable so I set mine to a setting of 300ms it was much more comfortable

Thanks, jaswilliams.  Did you notice any difference in any centrals (if you had any) when you changed it from min to 300ms?
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#95
RE: Bi-Level, S, ST, ASV??
The effectiveness of the ST did not seem to change increasing the rise time only improved the comfort I used the ST for 30days as a trial as that is what my dr prescribed. I was already using a self purchased ASV which was more effective and comfortable but I appreciate not suitable for your dad. If nothing else it did kinda work.
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#96
RE: Bi-Level, S, ST, ASV??
I came across this video from Philips that describes their AVAPS system and compared it to ST.  This is a useful video because it shows how the machine is intended to address the same issues as ST, but in a more intelligent manner.



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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#97
RE: Bi-Level, S, ST, ASV??
Thanks, again for all the feedback... doing a lot of reading and learning...

Another discrepancy I see is that the default Ti min is 0.3s and Ti max is 2.0s. The clinician guide says for a BPM of 15, the Ti min should be 1.0s. I see many short inspirations (< 1s) leading up to centrals. I am going to find out exactly how ALL the settings in the sleep study were set.

When a timed breath kicks in from BR, is that indicated in OSCAR anywhere, or can it not be differentiated from a synchronous breath when reviewing OSCAR data?
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#98
RE: Bi-Level, S, ST, ASV??
The general guidelines from the clinical manual for Ti Min are exactly what I would start with if not for the titration recommendation. The strategy of a longer Ti Min is to maintain and protect the IPAP, even if the patient effort seems to cycle to zero or expiration. This was the timing the technician needed to achieve the volume goals in the titration. This would be done automatically and as needed with AVAPS / iVAPS, as well as increasing PS as needed on a breath by breath basis. With ST / T we only have a timed function and no logical loop-back control from the tidal volume or minute vent. The technician acknowledges this may over-ventilate in NREM in order to maintain REM. These are a couple reasons VAP therapy makes sense. The ST has limited tools with which to ensure ventilation goals, and there is a smarter, better solution. I can't tell if the technician intends to use ST or T mode and you might want to call on that. My thought with ST is that it at least allows for spontaneous effort, while T is entirely dictated by the machine; otherwise they will work the same with the Ti Min, Ti Max or Ti set at 1.8.
Sleeprider
Apnea Board Moderator
www.ApneaBoard.com

____________________________________________
Download OSCAR Software
Soft Cervical Collar
Optimizing Therapy
Organize your OSCAR Charts
Attaching Files
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How To Deal With Equipment Supplier


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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#99
RE: Bi-Level, S, ST, ASV??
I have been doing a lot of reading.... :Smile You all probably know this already, but I will state some interesting things I learned.

Devices... I appreciate all the links above... seems like progression from ST to AVAPS to AVS is really only about a few basic differences.  Correct me if I am wrong.
     ST=Fixed pressure support (Vt can get out of whack)
     AVAPS=Variable pressure support to maintain approximate minute average Vt level... slow changing.. over minutes.
     AVS=Variable pressure support and fast changing to react immediately to users changes.

SERVE-HF only accepted people with predominant CSA... >50% centrals, and >10 AHI centrals alone.  It did not specifically state this, but I assume that is all pre-treatment... ie. not including treatment emergent centrals.  And the theory on what caused their negative findings (obviously no conclusive evidence), the report states that the theory is related to the elimination of centrals and not necessarily the mechanism of doing it.  That predominant centrals may be some coping mechanism for HF, and by eliminating them, you are removing this coping mechanism and allowing the HF to get worse.  They obviously cannot draw any conclusions outside the scope of the trial, but they do state that OSA predominant people may be different... in that OSA causes much more stress on the heart and the elimination of OSA is most likely helpful to HF patients.  But they are also questioning whether it was algorithm induced... ie. is there a difference between ResMed ASV and Respironics ASV.

I am a bit disappointed with the ResMed 10 ST... ResMed told me that it DID have clear airway detection, but it does not.  Add to that the easy breath that you all told me it was missing, and it feels like you pay premium for less features.  It appears that the Dreamstation BiPap S/T DOES have clear airway detection... does anyone know if it also has a comfort wave form like Easy Breath?  And is it customize-able for rise time, sensitivity, etc?  Any drawback to Dreamstation BiPap S/T when compared to ResMed AirCurve 10 ST or is it a clearly better product?
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RE: Bi-Level, S, ST, ASV??
You have been doing your homework, and these are complex issues to work out. I think the function of a Philips Dreamstation ST and the Resmed Aircurve ST is fairly similar. When we view mask pressure wave forms on the Dreamstation, they appear square wave, however I think they have BiFlex or Rise Time settings which might make a difference. The technological edge for respiratory failure therapy has got to go to AVAPS / iVAPS, and this is particularly true in the present case where the need for respiratory assistance (PS) varies with sleep position and sleep stage. I have never seen "good" results and comfort on a ST, but most of the people I have observed using it have pretty serious COPD or other pulmonary condition, and even there, users with high pressure support seem to swing between over-ventilated and under-ventilated. People using the ST in S mode are on fixed bilevel, and I don't typically see pressure support greater than 4 or 5 in that mode before central apnea kicks in. I think based on the problem of LVEF, ASV is not going to happen.

I'll be very interested to hear how your discussion with the doctor goes. I hope he respects that you have researched the issue, and expresses his opinion on the best way to proceed in a way that shows he has knowledge of the options and has thought about it and expects you will understand his rationale. The majority of doctors in this field do not have that temperament, but we an always hope. The most useful conversation would be to better understand your dad's respiratory failure mode; whether this is being looked at as central apnea, or physiological respiratory failure. The latter would be better addressed by ST or VAPS, while the former falls into the ASV category which appears to be disqualified. What I'd want to understand is why VAPS would not be a better solution than the comparatively primitive ST.
Sleeprider
Apnea Board Moderator
www.ApneaBoard.com

____________________________________________
Download OSCAR Software
Soft Cervical Collar
Optimizing Therapy
Organize your OSCAR Charts
Attaching Files
Mask Primer
How To Deal With Equipment Supplier


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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