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Interpreting the Encore smart card data for the BiPAP ASV
I am a Physician Assistant who has been working in sleep medicine for the past 18 months. We began using BiPAP STs and ASVs about six months ago. Sadly, our tech support for these Respironic machines has been paltry. I get different answers from different people supporting our clinic.
I have difficulty determining what the data means after I download the smartcard. It seems that I am to take it on faith that the AHI that I see (it is always invariably high) are central events that the card captures. However, I am told (with some hesitation) that the AHI should be ignored as "the centrals are recorded but are of no concern because they are being treated." I do understand the difference between an obstructive event and a central event; however, I don't like treating my patients based upon faith.
As the ASV does not report Centrals and Obs. events separately, when I see an AHI of 24 or so, I am told to ignore it as they represent treated centrals (I guess this is just a rewording of the comments above, sorry.)
I have read that a Nonresponsive event is just another name for centrals. Is this correct?
Please respond to me at my email address. I really want to master the ST ASV issue before I retire. My sleep med. MD is even more lost than I. Thanks for your tutorship.
I have difficulty determining what the data means after I download the smartcard. It seems that I am to take it on faith that the AHI that I see (it is always invariably high) are central events that the card captures. However, I am told (with some hesitation) that the AHI should be ignored as "the centrals are recorded but are of no concern because they are being treated." I do understand the difference between an obstructive event and a central event; however, I don't like treating my patients based upon faith.
As the ASV does not report Centrals and Obs. events separately, when I see an AHI of 24 or so, I am told to ignore it as they represent treated centrals (I guess this is just a rewording of the comments above, sorry.)
I have read that a Nonresponsive event is just another name for centrals. Is this correct?
Please respond to me at my email address. I really want to master the ST ASV issue before I retire. My sleep med. MD is even more lost than I. Thanks for your tutorship.
Views: 408
Replies to This Discussion
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Permalink Reply by RichM on
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I have a ST my doctor did not want to get me a ASV. I have not sent my card in yet to see what is given on a ST. I do know that when I started using the ST I could not use my OptiLife Nasal Pillow due to the pressures. I used my Fisher and Paykel FlexiFit HC432 Full Face and it made allot of difference and a lot quieter. I don't have a reader or software, but my DSE said she would print me a copy when she does mine. But she has not ask since I got it 3 weeks ago. I would like to know anything that it would show and also how do you configure it. Would it show anything on the machine display ? I have both OSA and CSP and need a back pressure. If you find out anything please let me know also.
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Permalink Reply by wlenz on
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Can cpap detect diff between central/obstruction? - one can!:cpaptalk.com
There was a detailed discussion that may be of interest to you on cpaptalk.com. Google the above line exactly and it should take you to this discussion thread.
Hope this helps,
Bill
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Permalink Reply by James Moriarty on
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Simplified : the asv works on the basis of a set minimum minute ventilation or a set minute ventilation range. A patient with an apneic event will be either a) obstructed or b) central or c) mixed. Without a polysomnograph the smart card won't know what is what because its only displaying events as apneic or hypopneas. You would only provide a patient with asv with known central sleep apnea.
(At least according to the manuals I've read). There are many articles on the AARC website that discuss neurological physiology and the relationship to breathing. The use of asv for mixed apneas is even contraindicated in the operations manual. A patient with Cheynes-Stokes breathing due to a stroke would be an example of someone requiring asv. How would you know the patient was having efforts from chest movement with an obstructed airway versus no chest movement with an open airway from the basis of data on the card? Its not possible to determine. You would require multiple leads to detect the neuromuscular activity...Sleep apnea with a pure central component is referred to as a "head" or some kind of brain dysfunction, requiring more sophisticated technology than a data card to determine the origin. It makes sense that the "central apneas" are being treated because in asv (adaptive servo ventilation) the machine is simply "kicking in" when the minute ventilation falls below a certain set threshold of say <3.0 liters per minute (treating the event through a mechanical pressure delivered breath). However, again one must not jump to a conclusion that its "central" without prior
polysomnographic evidence or witnessed therapist observation of such an event.
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James, do you have the same type of info for the BIPAP ST that is what I have and I would love to learn more about what the machine is doing and I would be able to understand what is going on at times and know when I need to talk to my Dr or DSE.
James Moriarty said:Simplified : the asv works on the basis of a set minimum minute ventilation or a set minute ventilation range. A patient with an apneic event will be either a) obstructed or b) central or c) mixed. Without a polysomnograph the smart card won't know what is what because its only displaying events as apneic or hypopneas. You would only provide a patient with asv with known central sleep apnea.
(At least according to the manuals I've read). There are many articles on the AARC website that discuss neurological physiology and the relationship to breathing. The use of asv for mixed apneas is even contraindicated in the operations manual. A patient with Cheynes-Stokes breathing due to a stroke would be an example of someone requiring asv. How would you know the patient was having efforts from chest movement with an obstructed airway versus no chest movement with an open airway from the basis of data on the card? Its not possible to determine. You would require multiple leads to detect the neuromuscular activity...Sleep apnea with a pure central component is referred to as a "head" or some kind of brain dysfunction, requiring more sophisticated technology than a data card to determine the origin. It makes sense that the "central apneas" are being treated because in asv (adaptive servo ventilation) the machine is simply "kicking in" when the minute ventilation falls below a certain set threshold of say <3.0 liters per minute (treating the event through a mechanical pressure delivered breath). However, again one must not jump to a conclusion that its "central" without prior
polysomnographic evidence or witnessed therapist observation of such an event.
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Permalink Reply by PD Laire on
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can someone tell me the difference between ASV, BiPAP and ST?
RichM said:James, do you have the same type of info for the BIPAP ST that is what I have and I would love to learn more about what the machine is doing and I would be able to understand what is going on at times and know when I need to talk to my Dr or DSE.
James Moriarty said:Simplified : the asv works on the basis of a set minimum minute ventilation or a set minute ventilation range. A patient with an apneic event will be either a) obstructed or b) central or c) mixed. Without a polysomnograph the smart card won't know what is what because its only displaying events as apneic or hypopneas. You would only provide a patient with asv with known central sleep apnea.
(At least according to the manuals I've read). There are many articles on the AARC website that discuss neurological physiology and the relationship to breathing. The use of asv for mixed apneas is even contraindicated in the operations manual. A patient with Cheynes-Stokes breathing due to a stroke would be an example of someone requiring asv. How would you know the patient was having efforts from chest movement with an obstructed airway versus no chest movement with an open airway from the basis of data on the card? Its not possible to determine. You would require multiple leads to detect the neuromuscular activity...Sleep apnea with a pure central component is referred to as a "head" or some kind of brain dysfunction, requiring more sophisticated technology than a data card to determine the origin. It makes sense that the "central apneas" are being treated because in asv (adaptive servo ventilation) the machine is simply "kicking in" when the minute ventilation falls below a certain set threshold of say <3.0 liters per minute (treating the event through a mechanical pressure delivered breath). However, again one must not jump to a conclusion that its "central" without prior
polysomnographic evidence or witnessed therapist observation of such an event.
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Permalink Reply by Duane McDade on
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Ok this is what I know about this. Central Apneas are very Rare. Something that almost looks like a central Apnea will occur when a patient is OVERTITRATED, or the pressure is too high. I score 10 sleep studies a week, i can go weeks without seeing a single central apnea. The only true Central Apneas occur in patients who brain shuts off and then back on . this is not very technical but that's the easiest way to explain it. It would be my guess that unless the doctor told you you had complex sleep apnea or something along that line, that you dont have central sleep apneas. Your Pressure is too high. You need a sleep study at a sleep lab that is aware of these rules. I know this whole thing is crazy but machines can not score sleep studies or give you the correct pressure.
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Also a Sleep med field here since 1999
Keep in mind that central apneas are also known to be caused by any medication that are depressive to the central nervous system. for example pain killers etc
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Permalink Reply by RockRpsgt on
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Opiates
LadySpring said:Also a Sleep med field here since 1999
Keep in mind that central apneas are also known to be caused by any medication that are depressive to the central nervous system. for example pain killers etc
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Permalink Reply by Mary Z on
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PD,
http://thesleepsite.com/content/view/76/91/
This site will give an overview of ASV.
Bilevel, or BiPap has two set pressures- an EPAP and a higher IPAP,ie. 4/8.
I don't know what ST is.
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