Bi-Level vs Bi-Level ST vs ASV Questions for CPAP Gurus

A few quick questions for all the cpap gurus on here. I'm currently on a ResMed AirCurve 10 ST. For my own understanding I'm trying to figure why exactly this is the type of therapy I need versus an Auto-titrating machine or an ASV machine. Note- I had 4 central apneas in my sleep study while on the cpap. I've been on treatment for one month and am averaging 1-3 AHI every night (down from an AHI of 90 in my sleep study), however, still experiencing symptoms.

What is the difference between Bi-level and Bi-level ST? I understand ST stands for spontaneous timed and I've tried to research what exactly that means but I'm not really understanding it.

Also, what are the reasons someone would be put on an ST machine versus a standard Bi-level or Auto Titrating Bi-level? It appears to me an Auto-Titrating Bi-level would be best but I'm not sure.

What are the pros & cons of a Bi-level ST machine versus the ASV machines? Does anyone have first-hand experience switching from a Bi-level machine to an ASV and seeing marketable improvements?

Lastly, I had originally downloaded the ResScan software but decided last night to also download the newest version of SleepyHead. ResScan will label all my apneas as Obstructive, whereas, Sleepyhead labels them as Unclassified apneas (could be central or obstructive but not enough data). Is this something I should look into more?

Thanks in advance,

Yub

Yub Yub wrote:Lastly, I had originally downloaded the ResScan software but decided last night to also download the newest version of SleepyHead. ResScan will label all my apneas as Obstructive, whereas, Sleepyhead labels them as Unclassified apneas (could be central or obstructive but not enough data). Is this something I should look into more?

It's just the way they get reported. Your machine (and my S9 Adapt) doesn't distinguish between central and obstructive apneas.
In ResScan they are just called OAs or apneas because I think they assume no centrals or something (never could find out why they elected to not separate the 2 events). So in ResScan you get OA and hyponeas only...I get the same thing.
Sleepyhead picks up on them as being unclassified because they aren't really named anything or fall within usual names.

As to why they gave you a ST instead of the ASV model...I don't know because 4 centrals during a sleep study doesn't normally earn you one of those high dollar specialty machines unless something else is going on.

What are your pressure settings? What mode of operation?
Do you have any history of lung issues like COPD or something like that?

Yub Yub wrote: What is the difference between Bi-level and Bi-level ST? I understand ST stands for spontaneous timed and I've tried to research what exactly that means but I'm not really understanding it.

Also, what are the reasons someone would be put on an ST machine versus a standard Bi-level or Auto Titrating Bi-level? It appears to me an Auto-Titrating Bi-level would be best but I'm not sure.

What are the pros & cons of a Bi-level ST machine versus the ASV machines? Does anyone have first-hand experience switching from a Bi-level machine to an ASV and seeing marketable improvements?

"bi-level" is a very broad brush. (the following is all related to resmeds, lest some respir person want to nitpick my nitpicking)

so there isn't any difference in bi-level ST and bi-level, since bi-level ST *IS* bi-level.

it's like asking 'what's the difference in a pickup and a 4wd pickup? well, nothing, unless you make assumptions about what a "pickup" is.

nitpicking aside, perhaps you're thinking of a bi-level "S" model, or spontaneous, meaning it only switches to inhale pressure (ipap) when it detects you're starting to take a breath.

the ST model works both on a trigger from you, and in timed mode, ie, "it's been too many seconds since bozo inhaled, I'll go ahead and switch to ipap to prompt him to inhale".

there's also a T mode that purely works on timing.

auto is just a S model with varying epap. same difference between cpap and apap. just with a bigger inhale/exhale pressure difference.

S and auto models don't address centrals, ST (because of the timed) can.

S/ST/T/Auto models don't vary ipap. ASV models monitors your "respiratory flow" (minute vent) and adjusts the pressure support, breath by breath, to keep your minute vent stable. I believe it was initially designed for people with CSR. it just happens to work fairly well for people with central apnea also.

Pugsy wrote:

Yub Yub wrote:Lastly, I had originally downloaded the ResScan software but decided last night to also download the newest version of SleepyHead. ResScan will label all my apneas as Obstructive, whereas, Sleepyhead labels them as Unclassified apneas (could be central or obstructive but not enough data). Is this something I should look into more?

It's just the way they get reported. Your machine (and my S9 Adapt) doesn't distinguish between central and obstructive apneas.
In ResScan they are just called OAs or apneas because I think they assume no centrals or something (never could find out why they elected to not separate the 2 events). So in ResScan you get OA and hyponeas only...I get the same thing.
Sleepyhead picks up on them as being unclassified because they aren't really named anything or fall within usual names.

As to why they gave you a ST instead of the ASV model...I don't know because 4 centrals during a sleep study doesn't normally earn you one of those high dollar specialty machines unless something else is going on.

What are your pressure settings? What mode of operation?
Do you have any history of lung issues like COPD or something like that?

I believe inspiration pressure is 13
Expiration is set at 8
I'm fairly certain these are the pressures but am not at home so not 100% sure.
The ResScan says the mode is Vpap S/T
No history of lung problems.
I apologize I probably should just post my entire sleep study results to make it easier

palerider wrote:

Yub Yub wrote: What is the difference between Bi-level and Bi-level ST? I understand ST stands for spontaneous timed and I've tried to research what exactly that means but I'm not really understanding it.

Also, what are the reasons someone would be put on an ST machine versus a standard Bi-level or Auto Titrating Bi-level? It appears to me an Auto-Titrating Bi-level would be best but I'm not sure.

What are the pros & cons of a Bi-level ST machine versus the ASV machines? Does anyone have first-hand experience switching from a Bi-level machine to an ASV and seeing marketable improvements?

"bi-level" is a very broad brush. (the following is all related to resmeds, lest some respir person want to nitpick my nitpicking)

so there isn't any difference in bi-level ST and bi-level, since bi-level ST *IS* bi-level.

it's like asking 'what's the difference in a pickup and a 4wd pickup? well, nothing, unless you make assumptions about what a "pickup" is.

nitpicking aside, perhaps you're thinking of a bi-level "S" model, or spontaneous, meaning it only switches to inhale pressure (ipap) when it detects you're starting to take a breath.

the ST model works both on a trigger from you, and in timed mode, ie, "it's been too many seconds since bozo inhaled, I'll go ahead and switch to ipap to prompt him to inhale".

there's also a T mode that purely works on timing.

auto is just a S model with varying epap. same difference between cpap and apap. just with a bigger inhale/exhale pressure difference.

S and auto models don't address centrals, ST (because of the timed) can.

S/ST/T/Auto models don't vary ipap. ASV models monitors your "respiratory flow" (minute vent) and adjusts the pressure support, breath by breath, to keep your minute vent stable. I believe it was initially designed for people with CSR. it just happens to work fairly well for people with central apnea also.

Ah I see. Thanks Palerider this makes more sense now. So the machine can switch automatically between spontaneous and timed modes?

Have you seen people on here switch from bi level to asv and see any benefits?

Well maybe you did better with the 5 cm difference between inhale and exhale for some reason than you did with single pressure or single pressure with exhale relief and with the Resmed machines that is just 3 cm using max EPR.

Sometimes people with lung issues do better with the larger pressure support that bilevel offers but it isn't just people with lung issues that like pressure support...heck I love 4 cm difference just from shear comfort. I don't have to have it and I can use a single pressure but having a 4 cm difference is just sweet.
Sometimes people need that difference because of aerophagia issues and using bilevel helps resolve those issues.
People with COPD often seem to need an even higher PS because of exhale difficulty.

If you didn't have numerous centrals in either the diagnostic or titration sleep study (and 4 over the entire night is far from numerous) I don't know that you really need or would benefit from ASV because I don't know that it would do something that you need that you aren't getting now.

I think most people know that I am using ASV now but I am using it because I like it and it lets me use a lower pressure at the beginning of the night while awake...that's the only reason.
I didn't go from apap to ASV directly though. I went to regular plain bilevel first. I did seem to notice an improvement in general (mainly in hours of sleep) with the change to plain bilevel and for me hours of sleep always translates into feeling better in general during the day. Going from plain bilevel to ASV bilevel didn't seem to do anything one way or the other in terms of how I felt or general sleep quality so no miracles with it but I just like being able to use lower pressures at the start of the night than I would have to use if I did regular APAP or regular bilevel because the ASV responds fast enough (the others can't respond that fast) to deal with my OSA. I have never had any real issue with centrals.
All my machines have been private purchase...I find a good deal and if I am fortunate enough to have the spare money then I act on the deal. I am comfortable experimenting with these machines but that's me and I am in no way suggesting that others do what I do just because I do it.

Yub Yub wrote:So the machine can switch automatically between spontaneous and timed modes?

Have you seen people on here switch from bi level to asv and see any benefits?

no, the machine cannot switch between the two. S is S, T is T, ST is a combination.

the ST machine can work in S, ST, T or CPAP mode, but it doesn't switch between them.

ST mode is spontaneous, as long as you breath as fast, or faster than the resp rate setting.

and, again, ASV *IS* bi-level.

Pugsy wrote:People with COPD often seem to need an even higher PS because of exhale difficulty.

COPD patients also benefit from having a short TI time, and a longer exhalation time, with high cycle sensitivity.

The recommended settings use a faster rise time to ensure that the lungs are filled quickly, and a high cycle sensitivity to provide an earlier cycle to exhalation. The rapid inhalation and prolonged exhalation will help to prevent auto-PEEP and preserve synchrony

(just fyi)