A little confused.
I found an article about the differences between CPAP, APAP, BiLevel and ASV. This one part confused me a little bit because I didn't know that a BiLevel can provide a backup breath like an ASV.
"Both BiPAP and ASV machines are able to provide different amounts of air pressure when a person is breathing in and breathing out. In addition, both kinds of machines can provide a backup breath if a person’s respiration slows excessively."
RE: A little confused.
I think overall the article is pretty good. Maybe the sticking point is the word "backup breath" I have both types of machines, and have tried both. I'll try to describe the sensation.
1. The bipap/bilevel machine - In the settings you set two different levels an Inspiratory (IPAP) and an Expiratory (EPAP) pressure. The machine detects when your breathing is either at the top or bottom of a breath and then switches to the other one.
2. The ASV machine. I have a ResMed ASV. It's supposed to basically record your normal breaths, then if it detects that your breathing is shallower (or nonexistent) it adds more pressure until the wave of your breathing looks normal again. In my case I've held my breath for a few seconds and you can feel it start to push against your lungs to get a breath. It's generally prescribed for mixed (sometimes called complex) apnea where you have both central and obstructive apneas. If you have CA's you're not even trying to breath, and that's generally what this is prescribed for. I have had problems acclimating to the doggone machine. It seems to "detect" an apnea, then push way too hard to fix the problem. Like my lungs are full and it's still pushing me. For that reason I've taken it off while I sleep.
RE: A little confused.
That article is over simplified.
CPAP (mode) is single pressure for both inhale and exhale delivering a constant pressure without changing.
APAP has the additional capability of increasing pressure when an obstructive events occurs. This feature allows the APAP to adapt, within reason, thru the night.
Some manufacturers implementation of pressure relief, such as Resmed's EPR, allow a limited differential pressure of up to 3cmw between inhale and exhale pressures similar to pressure support or PS on BiLevels. This in most cases will provide the best treatment for hypopneas, RERAS, and flow limitations.
BiLevels without backup. These do not have a timed backup rate which can be used to initiate a breath if you "skip" one. There are 2 modes for these.
"s" or Spontaneous mode is 2 set pressures (BiLevel) one for inhale and one for exhale the difference is called pre#ure support. This is the BiLevel equivalent of a CPAP )mode)
Auto mode such as Resmeds VAuto is the equivalent of the APAP and has the ability to increase pressure when obstructive events occur.
All of the above are designed to do nothing if a central apnea is detected. These two BiLevels are typically prescribed for users who require high pressures as BiLevels can provide 25cmw pressure vs 20cmw pressure with CPAPs. They are also prescribed for noncompliant users with OSA because of the greater comfort resulting from the PS. Do note that CPAPs and APAPs from ResMed have EPR which can deliver the equivalent of 3cmw PS.
Note: all of the above have the same billing code.
BiLevel with Backup. These will initiate an inhale pressure to initiate a breath if you don't spontaneously breathe before the backup period expires. This will treat Central apnea or various other issues.
ASV does work on the same breath that an issue occurs on via manipulation of pressure to maintain volume, either minute vent or Tidal volume depending on the manufactures. It is interesting to note that though an ASV is designed to treat centrals it does not detect the..
IVAPS is another advanced BiLevel that can be set to deliver as specified volume.
RE: A little confused.
@David Clark,
I have a little rant you may be able to help me with. Reading this article brought forward many questions that have promulgated in my mind during this Apnea Odyssey...
Most of this comes from my personal experiences during diagnosis, post diagnoses, and application of therapy, augmented by personal "research" to resolve applied therapy issues, unresolved by those who applied the original miracle cure... Most of my rant really has to do with the lack of coherence in a pretty clearcut haze.
Why isn't ASV universal and CPAP reserved for those with heart conditions? Considering Sleep Apnea without the comorbidity of heart conditions is far more common than heart conditions with it. When did treating those with non-comorbid apnea become niche? I get that the technology evolved, the question is why didn't the application evolve? Rationale for CPAP, APAP, BI-PAP, ASV? Isn't an ASV machine capable of all of the above. Wouldn't it be better if all machines were capable of all? Though every machine would be more expensive to build due to components and to some extent software, wouldn't the overall expense be diminished due to consolidation of effort on one device and the expense spread over all users. Even considering the original argument above, I doubt even those with heart conditions all have simple apnea. Since we have all discovered that simple sleep apnea isn't so simple, why the complexity of devices when one properly equipped and software driven device can service all?
Since ASV is expensive and used only for certain patients... (the most common excuse) Universal ASV would reduce the price of ASV. It really sounds to me that many people would benefit from ASV options, but prescribing ASV to all patients would increase the workload of those prescribing them due to configuration customization, not necessarily the expense of the equipment. It's so much easier to cookie cutter autopap 5-15 or worse 5-20, ramp 45 minutes (during which little therapy is happening and zero events are logged) EPR 3 On Ramp (which aids adjustment to therapy but does nothing to improve therapy after ramp), Climate control auto, good luck, don't call us we'll call you if you fail compliance.
The Resmed ASV machine is housed in exactly the same housing as the Airsense 10 indicating many common components. Is the extra expense actually due to limited prescription, therefore limited supply because of some software and maybe a different motor and actuator? Basically false supply and demand?
Configuration of ASV is more complex, but there could easily be a grid of settings applied based on sleep study results that could be changed later as the patient adjusted to therapy and the realities of sleeping in the home environment became more evident. Many folks would be set and forget, happy with treatment as is. Those who wish to refine treatment would have finer adjustments to do so, those misdiagnosed due to lack of appearance of symptoms during a sleep study would have a ready avenue to adjust settings with or without direct supervision.
Am I wrong wondering why this whole system isn't a little more streamlined toward serving the patient and a little less toward serving the dollar? Is it really this complicated? (rhetorical question)
Side note: Not advocating monopoly by using Resmed as the example, its just the only company I'm familiar with. [Go Aussies!]
RE: A little confused.
Sleepy, the cost is in the software development and testing for each device. The difference between devices is primarily software and a little bit of casing, at least for ResMed and by correlation for other vendors as well. Neither Apneaboard nor I support the alteration of these devices to other than what the manufacturers have set them up as. That said much of what you have ranted about regarding machine capability is true. Don't ask how as that is against this forums policies.
RE: A little confused.
@Gideon
Who makes a BiLevel with backup?
RE: A little confused.
Nearly everyone who makes a BiLevel, ResMeds is the "ST" the "T" is for Timed..
