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Are Auto-Adjusting Machines Smart or Dumb?
breaking this off as a separate topic, which explains why this is an excerpted from another comment i made on a different thread, but the ultimate question is just how smart or dumb auto-adjusting machines are...
"On the one hand, I'm with Duane that these machines are too "dumb" as they stand right now. Think about it: the machine doesn't know until it's too late -- until you already have had the apnea event -- that it needs to up the pressure. It's purely reactive, not proactive. But on the other hand, I think the future of auto-adjusting machines is bright -- i can see the day in the not too distant future when they displace CPAP altogether. I think that day will have arrived when the APAPs are smart enough to detect on a breath-by-breath basis what is going on with airflow, and to raise the pressure proactively to eliminate the apnea before it occurs. The machines sort of have to predict the future, and react just in time to save the patient any arousal. Or are there machines out there that already do that and I'm just not giving them enough credit?"
"On the one hand, I'm with Duane that these machines are too "dumb" as they stand right now. Think about it: the machine doesn't know until it's too late -- until you already have had the apnea event -- that it needs to up the pressure. It's purely reactive, not proactive. But on the other hand, I think the future of auto-adjusting machines is bright -- i can see the day in the not too distant future when they displace CPAP altogether. I think that day will have arrived when the APAPs are smart enough to detect on a breath-by-breath basis what is going on with airflow, and to raise the pressure proactively to eliminate the apnea before it occurs. The machines sort of have to predict the future, and react just in time to save the patient any arousal. Or are there machines out there that already do that and I'm just not giving them enough credit?"
Views: 83
Replies to This Discussion
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Permalink Reply by RockRpsgt on
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This is definately the debate of the day. I would not say dumb. They do the job they were programmed to do. No more no less. That's better behavior than I get from my kids. I would say that the machines are lacking. I strongly agree with Duane that they are being a little abused right now.
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Permalink Reply by BPLink on
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I think that the day will come when apnea will be treated/stopped/eliminated completely by a means better than masks and machines.
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Permalink Reply by Judy on
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Rock Hinkle said:You could always pressurize your bedroom.
Giggle. Snork. Yeah, right, Rock Hinkle. Giggle.
The APAPs are only as smart as they are programmed to be. The sad thing is that they are being misused so often right now. Not abused, misused - and mostly by professionals who set them wide open 4 cms to 20 cms. I would think this new policy of Medicare's coming into being or already approved of a THREE MONTH trial w/APAP "IF" handled PROPERLY by the dispenser might be a better way to get more people on CPAP who need it than our limited number of sleep labs can handle right now.
We ALL know that THE MASK is the key once the proper or close to proper pressure has been found. An APAP isn't going to be able to find that proper pressure if the patient is experiencing high leaks. IF the dispenser provided education and were checking the data once a week at first, then maybe even every two weeks until the patient has an acceptable mask and leak rate so that there could be more confidence in the data it collects the APAPs could do a decent, better than nothing job. The short coming of this is that an APAP can't even begin to detect the other sleep disorders people may suffer from.
The way I understand this newly approved or about to be approved APAP screening by Medicare, after three months those who have been successful w/APAP will be provided w/a CPAP and those who were not successfull will be eligible for full PSG testing.
And ... correct me if I'm wrong, Rock and our other PSGTs, but even RPSGTs can only RESPOND to events, not really anticipate them. Well, I guess there are cases where you can anticipate an event, but you really can't respond to them until they actually start, such as responding to an hypopnea soon enough could stop an actual apnea?? The key tho is that you can respond faster than an APAP? Am I way off base here??
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Permalink Reply by Rock Conner RRT on
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For payer-driven reasons we do 2-4 week APAP titrations, then dispense CPAP based on the results w/ clinical correlation. This process has served our patients well, but I would like to leave them on APAP because our pressure needs vary throughout a given night, & over time. In fact, I'd like all of us to be on APAP.
Early during most sleep nights, when REM and resultant apneas/hypopneas are infrequent, we with OSA need less pressure than we need late in the sleep night when REM periods are longer & there are more frequent sleep disordered breathing events. APAP keeps the delivered pressure nearer real-time need than CPAP.
Similarly, our pressure needs can change over time. Weight gain or loss, upper or lower respiratory illness, muscle tone loss with age, and other factors can lead to a change in one's optimal pressure. CPAP does not respond to such changing conditions; APAP does.
I don't think APAP is the ultimate solution. A sleep specialist for whom I have great respect thinks that the standard of care for OSA patients will eventually look like what we today call ASV. I think that most OSA patients will eventually be treated with effective body mass management therapies. For now, though, in our current reimbursement & cultural climate, I like the APAP model.
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Permalink Reply by Mike on
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so much wisdom in this post, thanks j n k. i agree wholeheartedly. and yes, time travel is a ways off, but i do see the day when every individual gets a machine that customizes its algorithm to the needs of that particular individual on a breath by breath basis. and that day is not here. in other words, the machine needs to "learn" what your individual needs are, and remember, all the time taking in new data to adjust its learnings and provide the proper treatment on a breath by breath, second by second basis. might sound like pie in the sky futuristic stuff, but given all the computing power out there, is there really a technical reason why this doesn't exist today? i don't expect an answer to that question. just sort of running stream of consciousness here.
j n k said:In my opinion, the way APAPs need to go is in the direction of providing full data in color from the screen, the same data that it now takes software and a computer to get to. The simple charts and timelines from the software could be shown on a screen on the top of the machine, like a smartphone has now. I see no reason that my PAP machine should be dumber than my cell phone.
Until time travel is invented, I don't expect my machine to predict the future. The idea isn't to eliminate ALL events anyway. Some events will happen. Even people without OSA have events. And human bodies have variations from one patient to the next. One patient may have the snores and flow limitations to let the machine easily know to raise pressure to prevent apneas in that patient, the next patient's body may be different. The algorithm is set for the majority of patients, so some are not well served without customizing the range.
Maybe one day the machines will be smart enough to learn a particular patient so that the machine slowly customizes to the patient. For example, the machine might learn that a particularly shaped flattening of the flow may need a quick reaction with one patient and not with another. Until that time, the trick is for us to use our data to customize our own auto machines for ourselves individually by finding the range that works best for us as individuals. The manufacturers don't want to highlight that need, because they advertise their machines as never needing any customiziation. They want docs to think the machines do just fine set 4-20 for everybody. And for some they may do OK set up like that. The biggest problem in the industry is that it hasn't embraced the need to educate patients to use their nightly data to customize their own machines. And that's as true of CPAPs as it is of APAPs.
The problem with the auto "debate" is that people debate the machines without agreeing on how the machines should be used. If someone says the machines don't work well, for example, I can agree with the point if that person is talking about one set up at 4-20 cm. I can disagree, though, in the sense that the machine CAN do a great job for the majority of patients if it is tweaked a bit to customize the range for the individual patients. Problem is, the machines aren't being advertised with customization and tweaking in mind. The studies show the machines do OK set wide open. In my opinon, they can do much more than OK if tweaked by the patient.
Really, the whole argument of APAP vs. CPAP is often a defacto argument between customization vs. no customization. After all, a CPAP is set for the patient, customized, at a PSG. So if the only way you use an APAP is set wide open with no customization, you have stacked the deck against the auto in how you have chosen to frame the debate. The answer is you can make a protocol for lab-titrating an auto, then you have the best of both worlds rolled into one. Or you can teach patients to self-titrate. Until a study is designed with that possibility, the auto studies are flawed as far as showing how effective an auto can be, imo.
The point too often missed, also, is that autos are an attempt to make the patient comfortable. So although some think autos are only second-class machines to be given to people who can't handle straight CPAP, the rest of us like being comfortable too. And if the only way to get a comfortabe machine is for a patient to find a way to fail CPAP, then my recommendation to every patient is that they all claim to fail CPAP so they can get a good machine. APAPs aren't really that expensive, after all.
End of rant.
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Permalink Reply by Daniel on
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Most modern APAPs already are proactive, not reactive. Every brand has its own unique algorithm to decide when to raise or lower the pressure. When APAPs first came out, some were indeed reactive. I don't think that applies to any APAPs currently being manufactured.
A Respironics REMstar Auto compares each breath to an ongoing moving average of previous breaths. If there is a decay in the air flow, it raises the pressure accordingly. It does this in conjunction with periodic proactive testing. If everything's going fine, what would happen if I raise the pressure a little bit? Does it make the moving average better or worse? What happens if I lower the pressure - better or worse. It does not wait for an apnea or hypopnea event before it does anything. That is why you will also see statistics in your Encore Viewer Data for FL - Flow Limitation and VS - Vibratory Snore. These are the proactive cues it is using to decide when to raise or lower pressure.
ResMed's algorithm is different. It is looking at your breathing on a breath-by-breath basis, looking for "flattening" of the breath cycle. If it sees breathing flatten out, it will raise the pressure. When we are first falling asleep, there is some expected flattening. That's why a ResMed AutoSet has a feature called "Settling Time." This is a period of time where the algorthm gets overridden. The pressure sits at the minimum level for the duration of the settling time so that you can fall asleep without the pressure kicking up on you. Some feel that ResMed's algorithm is more "aggressive," resulting in higher pressures. Others say it is more effective.
The interesting thing is that it isn't very difficult to proactively determine when to raise the pressure. The tough part is to know when to lower it. After all, isn't the goal of an autoPAP to deliver the minimum necessary pressure?
Getting back to the original question, APAP Smart or Dumb? I vote for Smart!
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Daniel Levy said:
... After all, isn't the goal of an autoPAP to deliver the minimum necessary pressure? ...
My thought, from the standpoint of one w/COPD, is that providing the minimum pressure necessary would be the way to go. But, repeatedly I see it said that the ideal pressure setting (at least if one is one straight CPAP) is the minimum pressure that will STOP all or most all apnea events. And I've seen it often said, even w/an APAP, the lower end of the pressure range should be the pressure that stops all or most apnea events.
Conversely, the recommendation seems to be to set the low end of the pressure range 1-2 cms below the titrated pressure if one has already had an in-lab titration and 1-2 cms above the titrated pressure for the higher end of the range. The preferred pressure range seems to be a 4 cms pressure range. Even the Default pressure support on my Resmed VPAP Auto is 4 cms.
And then there are all those sleep doctors and local DME RTs who set the APAPs wide open 4 -20 cms.
Confused? Confusing? Are these all theories? Does anyone really know how to best make use of an APAP? The "professionals"? The manufacturers? The experienced APAP users?
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You are not off base at all Judy. There is no right answer to this as of yet. I do disagree a little with the fact tha t a well trained tech can predict events and adjust accordingly.Snoring and RERAS are one way to determine these that a machine does not take into effect. I am now being trained to see blockage in the respiratory flow of the psg before it actually results in an event. personally I am not yet trained in this art, but I am getting there. I will see if I can find and post the flow charts that explain this. Some techs believe that you can tell alot about the types of blockage based on whether or not the snore is on inhalation or exhalation. Also mouth breather vs nasal breather. All of these can be factors in determining events before they happen. At least in theory for me anyway. I am still surfing this learning curve. It is these reasons that titrations are considered an art. I believe that these are also the same reasons that sleep proffessionals fight for titration studies. This same debate can also be applied to the "scoring on the fly" arguement. Techs that score durring the day don't actually get to see or here everything that happens in real time. This can sometimes impair their interpretation of the study, especially if the aquisition tech did not take good notes. Auto titration is definately here to stay. I just don't think that a machine can completely interpret a study on a case by case situation like a human. If we continue to allow auto titration without parameters I believe that we will start to see more and more problems due to the different complexities of apnea.
Judy said:Rock Hinkle said:You could always pressurize your bedroom.
Giggle. Snork. Yeah, right, Rock Hinkle. Giggle.
The APAPs are only as smart as they are programmed to be. The sad thing is that they are being misused so often right now. Not abused, misused - and mostly by professionals who set them wide open 4 cms to 20 cms. I would think this new policy of Medicare's coming into being or already approved of a THREE MONTH trial w/APAP "IF" handled PROPERLY by the dispenser might be a better way to get more people on CPAP who need it than our limited number of sleep labs can handle right now.
We ALL know that THE MASK is the key once the proper or close to proper pressure has been found. An APAP isn't going to be able to find that proper pressure if the patient is experiencing high leaks. IF the dispenser provided education and were checking the data once a week at first, then maybe even every two weeks until the patient has an acceptable mask and leak rate so that there could be more confidence in the data it collects the APAPs could do a decent, better than nothing job. The short coming of this is that an APAP can't even begin to detect the other sleep disorders people may suffer from.
The way I understand this newly approved or about to be approved APAP screening by Medicare, after three months those who have been successful w/APAP will be provided w/a CPAP and those who were not successfull will be eligible for full PSG testing.
And ... correct me if I'm wrong, Rock and our other PSGTs, but even RPSGTs can only RESPOND to events, not really anticipate them. Well, I guess there are cases where you can anticipate an event, but you really can't respond to them until they actually start, such as responding to an hypopnea soon enough could stop an actual apnea?? The key tho is that you can respond faster than an APAP? Am I way off base here??
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Rock thank you for the insight. I do see a need for the auto system. I guess when I first posted this I did not account for positonal therapy, or stage therapy. I have learned a great deal about both of these since the beginning of these post.
Rock Conner RRT said:For payer-driven reasons we do 2-4 week APAP titrations, then dispense CPAP based on the results w/ clinical correlation. This process has served our patients well, but I would like to leave them on APAP because our pressure needs vary throughout a given night, & over time. In fact, I'd like all of us to be on APAP.
Early during most sleep nights, when REM and resultant apneas/hypopneas are infrequent, we with OSA need less pressure than we need late in the sleep night when REM periods are longer & there are more frequent sleep disordered breathing events. APAP keeps the delivered pressure nearer real-time need than CPAP.
Similarly, our pressure needs can change over time. Weight gain or loss, upper or lower respiratory illness, muscle tone loss with age, and other factors can lead to a change in one's optimal pressure. CPAP does not respond to such changing conditions; APAP does.
I don't think APAP is the ultimate solution. A sleep specialist for whom I have great respect thinks that the standard of care for OSA patients will eventually look like what we today call ASV. I think that most OSA patients will eventually be treated with effective body mass management therapies. For now, though, in our current reimbursement & cultural climate, I like the APAP model.
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Jnk I was told on a tech site that there is actually no cost difference between straight CPAP vs Auto CPAP from the manufacturer. The reason for this being that the makers are trying to push the field in this direction.
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Rock Hinkle said:You could always pressurize your bedroom.
I used to wonder about this very question myself. Or its varitation - If wearing a mask is so uncomfortable, why not have the hose feed a plastic bag tied around your neck (with exhalation holes, of course)? Seems logical to me.
The answer seems to be in your ears. If your ears are getting the same pressure as your upper airway, it isn't really positive pressure at all - it's just the room pressure.
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