No AHI Data on the Adapt SV

[DrowzyDave]

i just got my Adapt SV two days ago (loving it by the way, it is sooo comfortable) and noticed that in the Results menu there was no AHI information. I figured that it would show up in the downloaded data so today I downloaded the data to ResScan and there is no AHI data there either.

Doesn't this machine track AHI and HI? Does it not record these events? Or is it so good at preventing them did Resmed decide it was not necessary to track them. Don't get me wrong, I love the machine and feel great in the mornig -- better than I did on the BiPAP ST or the VPAP III ST -- but I just assumed that all data capable machines tracked this important determinant of treatment success. If it doesn't track AHI, what parameter should be used to guage the effectiveness of treatment -- other than the subjective "how do you feel'?

Dave

[Snoredog]

I wonder if the new Respironics AVAP has AHI, doesn't say in the specs.

http://bipapavaps.respironics.com/

[billbolton]

noticed that in the Results menu there was no AHI information.

Is AHI a meaningful measure for a device that is aimed at treating Central Sleep Apnea and Cheyne-Stokes Respiration?

Cheers,

Bill

[Snoredog]

yeah I guess trying to count how many times you stopped breathing per hour would be asking for too much even for that machine or if it stabilized your breathing.

you would think if it prevented all events it would say so on the LCD like breathing normalized.

but somewhere they once counted up the CA's to come up with a CA indice of >11 per hour or more to determine if the disorder was the primary disorder.

[dsm]

noticed that in the Results menu there was no AHI information.

Is AHI a meaningful measure for a device that is aimed at treating Central Sleep Apnea and Cheyne-Stokes Respiration?

Cheers,

Bill

[dsm]

[quote="DrowzyDave"]i just got my Adapt SV two days ago (loving it by the way, it is sooo comfortable) and noticed that in the Results menu there was no AHI information. I figured that it would show up in the downloaded data so today I downloaded the data to ResScan and there is no AHI data there either.

Doesn't this machine track AHI and HI? Does it not record these events? Or is it so good at preventing them did Resmed decide it was not necessary to track them. Don't get me wrong, I love the machine and feel great in the mornig -- better than I did on the BiPAP ST or the VPAP III ST -- but I just assumed that all data capable machines tracked this important determinant of treatment success. If it doesn't track AHI, what parameter should be used to guage the effectiveness of treatment -- other than the subjective "how do you feel'?

Dave

[DrowzyDave]

Is AHI a meaningful measure for a device that is aimed at treating Central Sleep Apnea and Cheyne-Stokes Respiration?

I would think that AHI is a meaningful measure in ANY device aimed at treating ANY apnea condition. What condition other than an apnea or hypopnea would trigger its intervention by increasing the pressure? I know it constantly recalculates target tidal volume to stablize breathing. (It does this beautifully by the way. My average pressure has been around 10. My VPAP ST was set to 10/16. The Adapt is sooo comfortable to use, I can't get over it.) But when I stop breathing it jacks up the pressure to get things going again.

My guess is that the Adapt SV will be the preferred unit for users with centrals.

The Adapt is AWESOME for users with centrals in my humble opinion.

Dave, as mentioned the Aussie version apparently has been upgraded to include some kind of AHI. I was told it was a software upgrade.

Any idea if the software upgrade is planned for the US version? Also, any thoughts on how one would go about getting their machine's software upgraded? Since I am probably not supposed to know that the machine doesn't track AHI I am probably not supposed to have access to the software update. And I doubt my RT could figure out how to do it even if she had the software in front of her. I would bet that the only way MY machine will get upgraded is if somehow I got a hold of the sottware and upgraded it myself. But I am sure I would not be considered qualified to do the upgrade because I do not have a respiratory therapist certification -- although I do have a Bachelors Degree in Management Information Systems.

Oh well.

Dave

[dsm]

Dave,

The reason the AHI is suspect on a machine that employs Assisted Servo Ventilation, is that these machines don't really track apneas as such.

Both the Vpap Adapt SV and the Bipap AVAPS primarily track ventilation and tidal volume (as does the Bipap S/T - even though the VPAP III & Bipap Auto do both).

They can respond to to minute ventilation & tidal volume almost instantaneously - technically within a breath thus the Adapt SV for example can detect a central in one breathing cycle and switch from passive ventilation to active on the fly. Centrals get smothered.

Apneas are more complicated in terms of type of response. If someone has an apnea, applying lots of pressure quickly is a no-no as that can cause further problems. Autos never try to clear an Apnea in a single breath - firstly they are slow to respond - normally it takes many seconds if not minutes just to raise pressure by 1 CMS, and also no Auto tries to increase pressure quickly if there is no flow in case it is a central as Autos are not designed to clear centrals & can't always tell the difference between a central and and obstruction if it happens quickly - Autos try to pre-empt Apneas by monitoring precursor signs & thus will usually have increased the pressure as an Apnea looms.

The SV & AVAPS type machines work on what rate of breathing is taking place & what volume of air the user is breathing. They track the users breathing pattern & try to maintain that pattern within certain design parameters.

These machines *can* respond immediately unlike Autos. As such though, they don't look for an Apnea & increase pressure they way we are used to with Autos. These machines 'smother' the events by switching from passive ventilation (following the user's breathing) to active ventilation (driving the user to breathing). They work to maintain the user's breathing pattern (based on prior tidal flow, breathing rate and air volume (minute ventilation).

They can adjust pressure in milliseconds if that is needed.

DSM

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CPAPopedia Keywords Contained In This Post (Click For Definition): bipap, AHI, auto

[Lubman]

Hats off to dsm for his excellent description.

I believe the reason that the software doesn't give any type of indicative index, in addition to the correct technical description above, is that no alternative method has likely been approved by the US FDA.

Everything sold in this country as a medical device needs regulatory approval.

For example, ResScan software pre market notification may be found at
http://www.fda.gov/cdrh/pdf5/K050775.pdf

If ResMed comes up with an acceptable "index" and it receives FDA
approval, then you may see it as a software option.

Keep you eyes on the FDA web site at http://www.fda.gov and in the upper
corner simply search for ResMed. Then look at the various items
that will be new and see if any cover an update to the Adapt SV.

At that point, then you can push your DME to ask the ResMed
rep for information.

Lubman

[DrowzyDave]

Hats off to dsm for his excellent description.

I second that. Thanks, DSM.

I would be willing to bet that by the way I feel in the morning, I am not having any significant apneas or hypopneas during the night. Tha Adapt is an incredible machine and is likely preempting apneas before they happen as you describe.

I will get a copy of my titration study next week when I meet with the sleep doc. I am very curious to see the results.

Thanks.

Dave

[Vasily]

As Snoredog as posted many times about the differences between Resmed and Respironics algorithms in APAP's. There is also a difference in the algorithms between the 2 SV machines. Resmed uses a 4 minute floating time which tracks the average minute ventilation, and Respironics uses a 3 minute floating time which tracks average Peak Flow. Of the 10 or so Pulmonologists that I have talked to, there is about a 55% (PF) 45% (MV) split as to which measurement more accurately predicts when a patients breathing is affected.

So much like the APAP's, the 2 different machines could have very different results for the same person.

The AVAP is going to be a totally different ballgame when it's released. It's main aim is at Cardiac patients who will require control of their mean airway pressures during treatment. There will be specific titration protocols, and increased requirements by Medicare for the RX of this machine.

On another note, I believe Respironics is pulling ahead of the game a little bit. They are releasing the new Omni system to sleep labs (some may already have them, but those are the test bed labs) in Oct. This is the Sleep Lab based titration machine, it will have CPAP/BIPAP/SV/AVAPS modes on it. So the tech will be able to seamlessly be able to switch between the modes as needed to titrate properly for each mode. I'm not sure if Resmed has anything in the works for their Lab based machines.

[dsm]

[quote="Vasily"]As Snoredog as posted many times about the differences between Resmed and Respironics algorithms in APAP's. There is also a difference in the algorithms between the 2 SV machines. Resmed uses a 4 minute floating time which tracks the average minute ventilation, and Respironics uses a 3 minute floating time which tracks average Peak Flow. Of the 10 or so Pulmonologists that I have talked to, there is about a 55% (PF) 45% (MV) split as to which measurement more accurately predicts when a patients breathing is affected.

So much like the APAP's, the 2 different machines could have very different results for the same person.

The AVAP is going to be a totally different ballgame when it's released. It's main aim is at Cardiac patients who will require control of their mean airway pressures during treatment. There will be specific titration protocols, and increased requirements by Medicare for the RX of this machine.

On another note, I believe Respironics is pulling ahead of the game a little bit. They are releasing the new Omni system to sleep labs (some may already have them, but those are the test bed labs) in Oct. This is the Sleep Lab based titration machine, it will have CPAP/BIPAP/SV/AVAPS modes on it. So the tech will be able to seamlessly be able to switch between the modes as needed to titrate properly for each mode. I'm not sure if Resmed has anything in the works for their Lab based machines.

[DrowzyDave]

Apneas are more complicated in terms of type of response. If someone has an apnea, applying lots of pressure quickly is a no-no as that can cause further problems. ...

These machines *can* respond immediately unlike Autos. As such though, they don't look for an Apnea & increase pressure they way we are used to with Autos. These machines 'smother' the events by switching from passive ventilation (following the user's breathing) to active ventilation (driving the user to breathing). They work to maintain the user's breathing pattern (based on prior tidal flow, breathing rate and air volume (minute ventilation).

They can adjust pressure in milliseconds if that is needed.

Thanks for the explanation, DSM. I am curious though it you could lay out these two hypothetical situations.

What would happen to a patient with mixed apnea on an Adapt if they were having an obstructive instead of a central?

What would happen to a patient with only obstructive apnea on an Adapt given the Adapt's response pattere?

Thanks.

Dave

[dsm]

Dave,

Because I am not an RT, I will offer my opinion as to what might occur. Will do some thinking on the questions & get back with how I believe they might respond.

DSM (more later)