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Permalink Reply by Mike on April 1, 2009 at 3:38am

i do know that Respironics compliance reports report certain events as NR -- Non Responsive, meaning Central. How it does that and whether it's truly smart enough to know are open questions.

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Permalink Reply by RockRpsgt on April 1, 2009 at 5:28am

seems like it would be a good question with all that we have learned about centrals recently. centrals can be caused by over titration, How does the machine know when to quit?

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Permalink Reply by Duane McDade on April 1, 2009 at 5:30am

It's hard for a human to tell the difference with more information .... for example on a polysomnoghraphic recording we have four items to show how the patient is breathing or not breathing. Six if you include snore and sa02. The best way to tell the difference in most cases is see where the effort starts on the chest and ab belts, after the event, and then it's still not cut and dry! The test will also show some type of trend. There is also periodic breathing, This a different kind of central Apnea. The ASV is going to try to adjust or read only by the pressures that the machine is/is'nt reading as one does/doesn't breathe. through the hose attached to the mask. the answer to your Question in my opinion is IT Can't.

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Permalink Reply by RockRpsgt on April 1, 2009 at 5:36am

So then If a person began to have CSA due to over titration would the machine continue to raise the pressure?

Duane McDade said:

It's hard for a human to tell the difference with more information .... for example on a polysomnoghraphic recording we have four items to show how the patient is breathing or not breathing. Six if you include snore and sa02. The best way to tell the difference in most cases is see where the effort starts on the chest and ab belts, after the event, and then it's still not cut and dry! The test will also show some type of trend. There is also periodic breathing, This a different kind of central Apnea. The ASV is going to try to adjust or read only by the pressures that the machine is/is'nt reading as one does/doesn't breathe. through the hose attached to the mask. the answer to your Question in my opinion is IT Can't.

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Permalink Reply by Duane McDade on April 1, 2009 at 5:40am

logic would be yes. That's why I don't trust the machines , they dont see the big picture. They have tunnel vision. they don't multitask well.

Rock Hinkle said:

So then If a person began to have CSA due to over titration would the machine continue to raise the pressure?

Duane McDade said:

It's hard for a human to tell the difference with more information .... for example on a polysomnoghraphic recording we have four items to show how the patient is breathing or not breathing. Six if you include snore and sa02. The best way to tell the difference in most cases is see where the effort starts on the chest and ab belts, after the event, and then it's still not cut and dry! The test will also show some type of trend. There is also periodic breathing, This a different kind of central Apnea. The ASV is going to try to adjust or read only by the pressures that the machine is/is'nt reading as one does/doesn't breathe. through the hose attached to the mask. the answer to your Question in my opinion is IT Can't.

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Permalink Reply by RockRpsgt on April 1, 2009 at 5:42am

Thanks Duane that is what I thought, just needed some verification.

Duane McDade said:

logic would be yes. That's why I don't trust the machines , they dont see the big picture. They have tunnel vision. they don't multitask well.

Rock Hinkle said:

So then If a person began to have CSA due to over titration would the machine continue to raise the pressure?

Duane McDade said:

It's hard for a human to tell the difference with more information .... for example on a polysomnoghraphic recording we have four items to show how the patient is breathing or not breathing. Six if you include snore and sa02. The best way to tell the difference in most cases is see where the effort starts on the chest and ab belts, after the event, and then it's still not cut and dry! The test will also show some type of trend. There is also periodic breathing, This a different kind of central Apnea. The ASV is going to try to adjust or read only by the pressures that the machine is/is'nt reading as one does/doesn't breathe. through the hose attached to the mask. the answer to your Question in my opinion is IT Can't.

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Permalink Reply by Duane McDade on April 1, 2009 at 5:47am

you are welcome my friend.

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Permalink Reply by Duane McDade on April 1, 2009 at 10:37am

What?? I can't believe that you think if techs and doctors dont understand Complex/ Central Sleep Apnea that someone who orders a machine will be blessed with all this knowledge just by reading the instructions that come with the machine?? And treat themselves ? I' ve done about 18 ASV/ VPAP ADAPT -SV's in the seven years of being a technician.
what I do know is this machine is not for everybody. Insurance companys might cut you some slack for COPD...maybe, but a Doctor must order this machine for COMPLEX Sleep Apnea, and You must be trained by the DME company(in my case this was RES MED.)to titrate this equipment right it only takes a few hours to learn. I still have all my information and can look at it if I forget how to use this complicated stuff. I don't mean to be so glib but what's your point the patients who needed these ASV's are doing well. The right tool for the right problem. Why is that Hard to understand?? all the techs I know have been trained on this equipment too, and they understand. Ok I'm done sorry I've been doing sleep studies all night and now I'm going home. Have a nice day.


j n k said:

I won't pretend to understand the machines very well; I barely understand the basics of my autobilevel! But I believe the general idea of the ASV is that you first titrate out the obstructive apneas by setting the exhalation pressure properly. Then the machine tries to even out the patient's breathing so that the patient doesn't keep alternating between overbreathing and underbreathing. Part of the idea, I believe, is that if you can use variable pressure support (pressure support is the distance between IPAP and EPAP at any given moment) to even out the patient's breathing, the CO2 levels in the blood will stabilize to the point that centrals should not occur. However, if centrals do occur anyway, there is a timed backup that will basically ventilate the patient until things get back on track. That is likely a gross oversimplification of the science, but I think it captures at least part of the approach that the machine was designed for.

My guess for the reasons that approaches such as that one are so hard to get off the ground is that the diagnosis is fairly rare, few techs have been allowed to see the machine in action with good results, and many docs tend to stay out of the machine realm completely and just leave all that stuff to the RTs. That is not a bad reflection on the docs, the techs, or the RTs--just a reflection of how clumsily the system itself is set up in some places. It can be a "left hand not knowing what the right hand has" sort of situation. So maybe the approach is a good idea, but only if there are people out there willing to step outside the normal diagnosis/treatment box for the patient whose needs might be met by such a machine.

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Permalink Reply by RichM on April 1, 2009 at 12:29pm

I was going to get a ASV but my Dr would not let me. He wanted me to have a ST instead. And that is what I have for my OSA and CSA's. When the DSE set it up for me I had problems with it. It would only give me a short breath and cut off in less then 1/2 sec and still had a big problem getting enough sleep. I took the machine with me when I had a appointment with my pulmonary Dr who is also my sleep Dr and attach to the sleep center where I had my testing at. I took it into the sleep center and explained to them what was happening and they had to ask around the group their how to set it up since they don't see many people on the ST (the same with the DME that I had to use) They did find someone their at the center who was trained on the unit and was able to change most of the timings that controlled how long it takes to give pressure and how long it will last and now it is working better. But I would still like to learn what each of the settings are and do and the documentation that they give you does not have any of that in it. Does anyone know how I can get the information for the ST that explains each of the settings and what they are used for. Also I would like to know what the difference between the ST and the ASV (Respironics) Thanks in advance

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Permalink Reply by RichM on April 1, 2009 at 1:33pm

Thanks for those links, but I am still looking for the setup guide for the Respironics S/T This will show what the setting are for the ST and what they mean. I just don't like having a machine that I don't know what it is doing and why. And from my experience with both the tech that original set it up and the sleep center that did some of the resetting both did not really know what they were doing (there own words to me) and could not answer what the other setting on the machine were or how to set them if they were needed or not. It does not give me much comfort that I am getting the needed help from them. I had ask the sleep center to get what info they can from the Respironics Rep when he comes in, but I have not hear anything so far from that. So I had put the request out here for group to help me. Again thanks for the links you gave me but they do not answer my questions.

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Permalink Reply by Mike on April 1, 2009 at 1:35pm

j n k -- this is approaching the kind of explanation i, for one, am looking for. i think you're capturing something important here -- that CO2 levels in the blood are what trigger centrals, and to the extent you can adjust those levels somehow, you can manipulate whether centrals occur. i have got to say i don't truly understand everything you said here yet, but i'm further along/on my way. i appreciate it.

j n k said:

Part of the idea, I believe, is that if you can use variable pressure support (pressure support is the distance between IPAP and EPAP at any given moment) to even out the patient's tidal volume relative to their breathing rate (or something like that), the CO2 levels in the blood will stabilize to the point that centrals should not occur. However, if centrals do occur anyway, there is a timed backup that will basically ventilate the patient until things get back on track.

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Permalink Reply by Mike on April 2, 2009 at 3:16am

RichM, look for and click on the listing (last one under the letter "B" for BiPAP) for the Respironics BiPAP S/T user manual, and there you download the pdf manual for the Respironics BiPAP S/T. is that what you were looking for?

RichM said:

Thanks for those links, but I am still looking for the setup guide for the Respironics S/T This will show what the setting are for the ST and what they mean. I just don't like having a machine that I don't know what it is doing and why. And from my experience with both the tech that original set it up and the sleep center that did some of the resetting both did not really know what they were doing (there own words to me) and could not answer what the other setting on the machine were or how to set them if they were needed or not. It does not give me much comfort that I am getting the needed help from them. I had ask the sleep center to get what info they can from the Respironics Rep when he comes in, but I have not hear anything so far from that. So I had put the request out here for group to help me. Again thanks for the links you gave me but they do not answer my questions.

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