APAP Does Not Work As Good as BiPap?

Darth Vader Look · Post by **Darth Vader Look** » Sat May 27, 2006 4:01 am

Well let me throw in my 2 Canadian cents into this part of the discussion for whatever they're worth. Guest you must remember that an auto must be set up right in order to function right for you. That means initially setting the lower and upper pressure limits 3 lower and 3 higher respectively in regards to your titrated value (the pressure value determined in sleep study that best clears any apneas you experience during sleep). For example, if your titrated pressure level is say 12 cms, you can't expect to set the auto's lower limit to 6 cms and expect it to clear an apnea event in a timely fashion. For that to happen the lower setting should be at least set at 9 cms and tightened up if it still isn't good enough. Even your titrated value may not be accurate especially if you were never on your back during your sleep study. If you do end up on your back while at home during sleep, a straight CPAP is very unlikely to clear the obstruction forcing you to wake up. This is the whole point with an APAP. Should you encounter this condition, the APAP will adjust up and exceed your titrated value in order to clear the obstruction. The upper limit is not as important as the lower limit provided it is at least 3 cms higher than your titrated level. The lower limit is the most important.

Does this mean you need an Auto PAP No, but the versatility of it is what makes it so desirable. The Pro 2 by Respironics would be just fine for you and records all the necessary data required.

Guest · Post by **Guest** » Sat May 27, 2006 10:35 am

Thank you Ric and Darth Vadar Look. I read your posts and re-read them and then re-read them again. This is all making sense now.

Ric wrote:Imagine you have a straight CPAP set at 10, say. Then you roll over in your sleep and manage to occlude your airway in a manner such that it will resist pressures up to and including 11, for example. How long before the CPAP machine is able to get you breathing again? Simple answer, it won't. You now have an apnea event that will cause an increase in arterial CO2 which will lead to a cortical arousal which will set in motion a physiological response that will eventuate into a postural rearrangement or stirring or exaggerated breathing response which will get you breathing again. CPAP is not involved. It is not ALLOWED to respond. How long does all this take? Mileage may vary.

Replay that, using an APAP set to a range of 10-16, say. Will the APAP detect the event. Hopefully. Will it respond? Probably. Can it "reach up" and attempt to deal with the situation. Certainly. Will it respond sooner than mother nature? That is where the debate lies. Does this contradict Bill's "unequivocal data"? No. Confusing? Yes.

The way I read the arguments, it is focused on a narrowly contrived situation, a sudden and large apnea, occlusive in nature, and centers on whether or not the machine can respond quickly enough to actually "prevent" an actual "apnea" as determined by the predetermined objective criteria for what will be recorded by the machine as an "actual" event having occurred. That there are indeed "tick marks" on our data somehow implies imperfection of a sort. Of course there are those pesky "centrals" that confuse the analysis. OK, the machine is allowed SOME tick marks.

That the APAP machine responds with higher pressure, even if it's late on arrival, and that it "loiters" at a higher pressure suggests that it COULD entirely preempt SOME events, the same way a CPAP preempts apnea events (non-events?) that WOULD HAVE happened absent the air pressure. Consider the following graph, and notice an event at about 2.5 hours. this patient shows an apnea, followed by a rapid rise from 7cm to 12cm pressure, and some disgusting snore sounds early on. Note too that the pressure lingers for nearly an hour at 12cm pressure for whatever reason it's algorithm told it to. Imagine further this patient's situation on CPAP set at a constant 7cm, which just HAPPENS to correspond to this patient's sleep lab titration. Who knows how many apnea tick marks are "missing" from this data? It's hard to quantify what DIDN'T happen.

Can the APAP beat "nature" at resolving an airway occlusion, at least SOME of the time? I would argue yes. Those are impossible to measure. It would only show up as a lower AHI. That the APAP doesn't do a perfect job of what it's doing doesn't bother me. That it does an adequate job most of the time is good. Does it do a BETTER job than a CPAP? I believe it does. But that doesn't end the debate.

(As an aside, I have tried to imagine the "perfect" APAP device. My inclination would be to have a jury of twelve wide-awake board-certified pulmonologists monitoring every breath, each with a finger on a button to raise/lower the pressure at any given moment, with some built-in protection that it could not raise or lower more than 1cm by a simple majority vote before they were allowed another round of consensus voting. (Not even Bill Gates would spring for that, but nevermind the cost). And more than likely one would wake up to find them debating global warming or Suns vs. Mavs, etc. and neglecting your therapy. That aside, I actually think the right kind of machine might do a better job of it, when they eventually "get it right", and when these puppies become "near-sentient".)

Darth Vadar Look wrote:Guest you must remember that an auto must be set up right in order to function right for you. That means initially setting the lower and upper pressure limits 3 lower and 3 higher respectively in regards to your titrated value (the pressure value determined in sleep study that best clears any apneas you experience during sleep). For example, if your titrated pressure level is say 12 cms, you can't expect to set the auto's lower limit to 6 cms and expect it to clear an apnea event in a timely fashion. For that to happen the lower setting should be at least set at 9 cms and tightened up if it still isn't good enough. Even your titrated value may not be accurate especially if you were never on your back during your sleep study. If you do end up on your back while at home during sleep, a straight CPAP is very unlikely to clear the obstruction forcing you to wake up. This is the whole point with an APAP. Should you encounter this condition, the APAP will adjust up and exceed your titrated value in order to clear the obstruction. The upper limit is not as important as the lower limit provided it is at least 3 cms higher than your titrated level. The lower limit is the most important.

Does this mean you need an Auto PAP No, but the versatility of it is what makes it so desirable. The Pro 2 by Respironics would be just fine for you and records all the necessary data required.

Those 2 posts should be required reading for everyone considering buying an APAP. The explanations are very clear and helped me understand how an APAP *can* preempt apneas, but *not* always especially if the low end of the range is set too low and not in the case as Ric described of

Ric wrote:The way I read the arguments, it is focused on a narrowly contrived situation, a sudden and large apnea, occlusive in nature, and centers on whether or not the machine can respond quickly enough to actually "prevent" an actual "apnea" as determined by the predetermined objective criteria for what will be recorded by the machine as an "actual" event having occurred.

NightHawkeye wrote:I hope the understanding gained from considering the machine limitations will help you fine tune your therapy.

The understanding I've gained in this topic is greater than I what I have learned in all the previous ones combined. Thank you gentlemen for your patience, your knowledge and for taking the time to pass it on. I will undoubtedly have more questions once I get my machine, and won't hesitate to ask them in the future. Thanks.

Guest · Post by **Guest** » Sun May 28, 2006 2:31 am

Anonymous wrote:Thank you Ric and Darth Vadar Look. I read your posts and re-read them and then re-read them again. This is all making sense now.

Ric wrote:Imagine you have a straight CPAP set at 10, say. Then you roll over in your sleep and manage to occlude your airway in a manner such that it will resist pressures up to and including 11, for example. How long before the CPAP machine is able to get you breathing again? Simple answer, it won't. You now have an apnea event that will cause an increase in arterial CO2 which will lead to a cortical arousal which will set in motion a physiological response that will eventuate into a postural rearrangement or stirring or exaggerated breathing response which will get you breathing again. CPAP is not involved. It is not ALLOWED to respond. How long does all this take? Mileage may vary.

Replay that, using an APAP set to a range of 10-16, say. Will the APAP detect the event. Hopefully. Will it respond? Probably. Can it "reach up" and attempt to deal with the situation. Certainly. Will it respond sooner than mother nature? That is where the debate lies. Does this contradict Bill's "unequivocal data"? No. Confusing? Yes.

The way I read the arguments, it is focused on a narrowly contrived situation, a sudden and large apnea, occlusive in nature, and centers on whether or not the machine can respond quickly enough to actually "prevent" an actual "apnea" as determined by the predetermined objective criteria for what will be recorded by the machine as an "actual" event having occurred. That there are indeed "tick marks" on our data somehow implies imperfection of a sort. Of course there are those pesky "centrals" that confuse the analysis. OK, the machine is allowed SOME tick marks.

That the APAP machine responds with higher pressure, even if it's late on arrival, and that it "loiters" at a higher pressure suggests that it COULD entirely preempt SOME events, the same way a CPAP preempts apnea events (non-events?) that WOULD HAVE happened absent the air pressure. Consider the following graph, and notice an event at about 2.5 hours. this patient shows an apnea, followed by a rapid rise from 7cm to 12cm pressure, and some disgusting snore sounds early on. Note too that the pressure lingers for nearly an hour at 12cm pressure for whatever reason it's algorithm told it to. Imagine further this patient's situation on CPAP set at a constant 7cm, which just HAPPENS to correspond to this patient's sleep lab titration. Who knows how many apnea tick marks are "missing" from this data? It's hard to quantify what DIDN'T happen.

Can the APAP beat "nature" at resolving an airway occlusion, at least SOME of the time? I would argue yes. Those are impossible to measure. It would only show up as a lower AHI. That the APAP doesn't do a perfect job of what it's doing doesn't bother me. That it does an adequate job most of the time is good. Does it do a BETTER job than a CPAP? I believe it does. But that doesn't end the debate.

(As an aside, I have tried to imagine the "perfect" APAP device. My inclination would be to have a jury of twelve wide-awake board-certified pulmonologists monitoring every breath, each with a finger on a button to raise/lower the pressure at any given moment, with some built-in protection that it could not raise or lower more than 1cm by a simple majority vote before they were allowed another round of consensus voting. (Not even Bill Gates would spring for that, but nevermind the cost). And more than likely one would wake up to find them debating global warming or Suns vs. Mavs, etc. and neglecting your therapy. That aside, I actually think the right kind of machine might do a better job of it, when they eventually "get it right", and when these puppies become "near-sentient".)

Darth Vadar Look wrote:Guest you must remember that an auto must be set up right in order to function right for you. That means initially setting the lower and upper pressure limits 3 lower and 3 higher respectively in regards to your titrated value (the pressure value determined in sleep study that best clears any apneas you experience during sleep). For example, if your titrated pressure level is say 12 cms, you can't expect to set the auto's lower limit to 6 cms and expect it to clear an apnea event in a timely fashion. For that to happen the lower setting should be at least set at 9 cms and tightened up if it still isn't good enough. Even your titrated value may not be accurate especially if you were never on your back during your sleep study. If you do end up on your back while at home during sleep, a straight CPAP is very unlikely to clear the obstruction forcing you to wake up. This is the whole point with an APAP. Should you encounter this condition, the APAP will adjust up and exceed your titrated value in order to clear the obstruction. The upper limit is not as important as the lower limit provided it is at least 3 cms higher than your titrated level. The lower limit is the most important.

Does this mean you need an Auto PAP No, but the versatility of it is what makes it so desirable. The Pro 2 by Respironics would be just fine for you and records all the necessary data required.

Those 2 posts should be required reading for everyone considering buying an APAP. The explanations are very clear and helped me understand how an APAP *can* preempt apneas, but *not* always especially if the low end of the range is set too low and not in the case as Ric described of
Ric wrote:The way I read the arguments, it is focused on a narrowly contrived situation, a sudden and large apnea, occlusive in nature, and centers on whether or not the machine can respond quickly enough to actually "prevent" an actual "apnea" as determined by the predetermined objective criteria for what will be recorded by the machine as an "actual" event having occurred.

NightHawkeye wrote:I hope the understanding gained from considering the machine limitations will help you fine tune your therapy.

The understanding I've gained in this topic is greater than I what I have learned in all the previous ones combined. Thank you gentlemen for your patience, your knowledge and for taking the time to pass it on. I will undoubtedly have more questions once I get my machine, and won't hesitate to ask them in the future. Thanks.

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): cpap machine, respironics, Titration, Arousal, CPAP, AHI, auto, APAP

Guest,

If this all makes sense to you then you have done remarkably well. You must pass on your secret.

One bit of caution though is that most of the folk posting here are posting a lot of opinions & some 'facts'. The only real 'facts' anyone can rely on are what the machine does in use and how a machine works for the individual.

The opinions being expressed are clearly very useful and very helpful but in the end that is all they are and I am sure the people posting them would agree. By the experienced ones expressing their opinions here and by debating them we all learn.

Good luck. in your quest.

Another Guest

Guest · Post by **Guest** » Sun May 28, 2006 12:34 pm

Anonymous wrote:Guest,

If this all makes sense to you then you have done remarkably well. You must pass on your secret.

One bit of caution though is that most of the folk posting here are posting a lot of opinions & some 'facts'. The only real 'facts' anyone can rely on are what the machine does in use and how a machine works for the individual.

The opinions being expressed are clearly very useful and very helpful but in the end that is all they are and I am sure the people posting them would agree. By the experienced ones expressing their opinions here and by debating them we all learn.

Good luck. in your quest.

Another Guest

I know there's a lot I don't know. But I think I understand enough to make a decision on what machine to buy. I get that everybody is sharing their opinion. I get that my results might be different from theirs. I believe I understand how the APAP is supposed to work and that it does preempt apneas. I also understand what is a fact of treatment for Bill won't necessarily be a fact of treatment for me. I understand why it is debated because people have varying degrees of success. I understand these varying degrees of success can depend on a lot of variables like whether the range is set properly, the kind of mask being used, if the mask is leaking, and whether the machine recognizes someone's breathing and apneas right. But I still will be trying the APAP because I believe it holds promise for me.

GoofyUT · Post by **GoofyUT** » Sun May 28, 2006 1:06 pm

These speculations are fascinating!!! Beyond that, they are very well thought out and very compellingly and concisely written.

However, the fact remains that , to the best of my knowledge, there has never been an empirically based study that demonstrates that APAP provides MORE effective therapy than CPAP or Bilevel-PAP does, no matter how efficacy is defined. Nor do I know of a study that shows that APAP titrates MORE accurately than PSG does (though there are studies that show that it works AS efefctively as PSG.

As long as this remains the case, both sleep docs and clinics, and more importantly, insurance carriers (particularly CMS), will be reluctant or unwilling to foot the bill for something that looks swell and seems to make lotsa sense but ain't been proven to be "best practice". Proven being the operative word.

So, lets continue to speculate and reason why APAP is so cool, and await studies that actually demonstrate this, cause that's all that CMS and health insurance industry cares about.

Chuck

APAP Does Not Work As Good as BiPap?

Speculations