Are Bilevel ST Machines Safe?

Hi, I'm new to the world of cpap so please forgive my neophyte status. I recently had a sleep study done and my doctor prescribed a bilevel ST machine. I had 80AHI with 64 OSA 14 CSA, no cheyne stokes respiration. I mentioned the ASV machine, since I had read online various threads saying it was better and that ST machines were old technology, but he said it wasn't what I needed and he's the doctor and I honestly still have no clue what an ST machine treats vs. an ASV machine since there is so much conflicting info online.

Anyway, I was researching the machines and I read that an ASV machine can kill you if your heart is dodgy / your left ventricle infraction rate is below somewhere around 50%. Just to put my "heart at ease" if you where, does the ST machine have the same issue?

I know the answer is "horrible idea" but if you had central apnea and used an auto cpap machine, would it make the central apnea worse and/or hurt you?

Yes, the ST is safe. For the most part it works like a standard Bipap but with a backup rate (BPM - breaths per minute) setting to help induce a breath when you are not doing so on your own.

If you did more reading you will find that people are now questioning the study that was done that caused all the panic over people with bad congestive heart failure (ejection rate of 45 or less and not 50) using ASV were dying at greater numbers than those not using ASV and they never could figure out what about the ASV might be so bad for CHF patients.
The study was a bit flawed. Small sample of people who were very sick to begin with and they weren't using their machines all night...most were less than 4 hours and some barely 4 hours.
So you take some very sick people who aren't using their machines all night and they died at a slightly higher rate than those not using ASV. Duh...maybe the untreated sleep apnea sleep might have had something to do with it you think????
No studies were done on people with heart failure issues who actually used their machines all night and every night. They took really sick people who didn't use their machines all the time and when they died they blamed it on the machine.

But this one study scared the hell out of the medical profession and they got where they didn't want anyone using ASV no matter how healthy their heart might be or might not be.

ASV machines don't really do anything that the ST machines or any other machines might do except auto adjust for both obstructive apnea and central apnea responses. No one could really say that the auto adjusting part was any more dangerous than the fixed responses of the other machines.

Your OSA is primarily obstructive with just a bit of central apnea thrown in. You probably breathe just fine on your own for the most part except for the OSA stuff and just have issues with centrals sporadically through the night.
The ST machine can deal with both obstructive and central apnea but it works on the premise that centrals are the primary bad guy here as it treats you like you have central apneas all night long. If you don't breathe on your own it will force a breath and a central apnea is when you don't breathe on your own. It deals with centrals by making a person take a big deep breath with large differences between inhale and exhale...and it does this with every breath all night long and not just as needed. ST machines can't do anything but fixed settings. You get the same settings all night long. Usually somewhere with at least an 8 cm difference between inhale and exhale....that's a big and very uncomfortable difference to be using with every breath all night long.

The ST machine can deal with obstructive apneas just like any other bilevel machine with the EPAP being high enough to hold the airway open...problem happens when you have to add in that big difference between inhale and exhale (called pressure support) to that EPAP needed to hold the airway open. Often those settings are pretty big and extremely uncomfortable an you have to use them all night long just in case you have an occasional central apnea.

The ST machine would be more appropriate if someone only had central apnea IMHO or if maybe they only needed an EPAP pressure of maybe 6 to hold the airway open for obstructive apnea prevention. Most people need much higher pressures than that though.
ST machines typically have to use settings that simply are very difficult for people to get used to and sleep with.

Wonder why they don't have ST with auto Bipap? I think it was the high pressure support and the fixed epap/ipap that just never worked for me.

tsduke wrote: ↑

Thu Feb 13, 2020 8:12 am

Wonder why they don't have ST with auto Bipap?

They already do ....it's called ASV.
One could configured the ASV so that it functions just like the ST if they wanted to.

Right, I get that, but obviously the ASV is much more than auto bipap with backup. It's smarter and smoother. The ST in my experience had terrible inhale/exhale transition and vice versa.

Both are safe when set up properly. The ASV study was garbage and should largely be ignored.

Nervouso wrote: ↑

Wed Feb 12, 2020 11:45 pm

Hi, I'm new to the world of cpap so please forgive my neophyte status. I recently had a sleep study done and my doctor prescribed a bilevel ST machine. I had 80AHI with 64 OSA 14 CSA, no cheyne stokes respiration. I mentioned the ASV machine, since I had read online various threads saying it was better and that ST machines were old technology, but he said it wasn't what I needed and he's the doctor and I honestly still have no clue what an ST machine treats vs. an ASV machine since there is so much conflicting info online.

Another God complex, full of shit doctor.

ST machines suck, to be effective at helping central apnea, they have to ventilate you with so much PS that they *cause* central apnea. They should only be used in extreme cases, if at all.

Nervouso wrote: ↑

Wed Feb 12, 2020 11:45 pm

Anyway, I was researching the machines and I read that an ASV machine can kill you if your heart is dodgy / your left ventricle infraction rate is below somewhere around 50%. Just to put my "heart at ease" if you where, does the ST machine have the same issue?

No, they can't, that was a "terrible" study that had very poor controls, very poor usage standards, using obsolete equipment with near death people, and only a barely statically significant differences in death rate between the old crappy asv cohort and the no asv cohort.

Nervouso wrote: ↑

Wed Feb 12, 2020 11:45 pm

I know the answer is "horrible idea" but if you had central apnea and used an auto cpap machine, would it make the central apnea worse and/or hurt you?

The ST isn't even auto, so it is "terrible" at treating obstructive apnea.

An auto CPAP would be better, and depending on what your central index is after you get used to it, then an ASV would be ideal.

tsduke wrote: ↑

Thu Feb 13, 2020 7:31 am

Yes, the ST is safe. For the most part it works like a standard Bipap but with a backup rate (BPM - breaths per minute) setting to help induce a breath when you are not doing so on your own.

Not really.

palerider wrote: ↑

Thu Feb 13, 2020 12:39 pm

tsduke wrote: ↑

Thu Feb 13, 2020 7:31 am

Yes, the ST is safe. For the most part it works like a standard Bipap but with a backup rate (BPM - breaths per minute) setting to help induce a breath when you are not doing so on your own.

Not really.

Not really what? That's quite vague.

raisedfist wrote: ↑

Thu Feb 13, 2020 9:06 am

Both are safe when set up properly. The ASV study was garbage and should largely be ignored.

Be *completely* ignored.

Ftfy

Thanks everyone for your replies, I feel a lot better now about everything, except for the fact I'll likely need to get another doctor for sleep apnea that knows more.

Nervouso wrote: ↑

Thu Feb 13, 2020 3:40 pm

Thanks everyone for your replies, I feel a lot better now about everything, except for the fact I'll likely need to get another doctor for sleep apnea that knows more.

that may well be true. they are kind of thin on the ground.

but once you get the proper doctor and machine, stick with the forum and we'll see you through better than most doctors will.

Or keep your existing quack and self advocate follow are advise and we can help you get better treatment

zonker wrote: ↑

Thu Feb 13, 2020 5:11 pm

but once you get the proper doctor and machine, stick with the forum and we'll see you through better than most doctors will.

Thanks everyone for the support. The local DME is having the machine, an AirCurve 10 ST delivered on Tuesday, the doctor wrote my prescription out super specific for that machine (probably gets a kickback or something from his attitude and adoration of it). Should I use it for a bit, adjusting the pressure manually (I doubt very seriously that 12ipap/8epap/10bpm is going to be perfect) to get some immediate relief and a better idea of how my apnea is responding/starting data before advocating for a different direction / doing something out of pocket?