need help with a new BIPAP machine

Bought the BMC G3 B25VT BiPAP. It's basically the Luna G3 BPAP. So when I hit the IPAP pressure that I set it goes back down almost immediately to EPAP, not every breath but it's very inconsistent. I played with the I sens and E sens settings, rise time, etc. it doesn't change at all.

I have a Prisma Smart CPAP and never had this issue, even though cpap doesn't do much for me either way. (UARS)

I don't have the VT variant but I do find that the basic BIPAP version in "s" mode does seem to cut off the inhale very short.....you can change the tmin value up which helps.....in "auto s" it seems much more comfortable.....I'm assuming that the VT is intended to be used with a target tidal volume to avoid this.....let us know how you.get on

Garethep wrote: ↑

Sun Dec 08, 2024 8:46 am

I don't have the VT variant but I do find that the basic BIPAP version in "s" mode does seem to cut off the inhale very short.....you can change the tmin value up which helps.....in "auto s" it seems much more comfortable.....I'm assuming that the VT is intended to be used with a target tidal volume to avoid this.....let us know how you.get on

I've been playing with the t min and max settings and yeah it makes the exhale part longer, but it's like, I have to nail it perfectly to breathe somewhat normally. with nasal obstruction that varies from night to night and even during different parts of the night, hard to see it being useful. sigh

So auto S doesn't have this problem for you? this one doesn't have an auto s mode. I went for the more expensive one because I thought I might need the T or S/T functions and all that.

johnydramachase wrote: ↑

Sun Dec 08, 2024 10:37 am

I've been playing with the t min and max settings and yeah it makes the exhale part longer, but it's like, I have to nail it perfectly to breathe somewhat normally. with nasal obstruction that varies from night to night and even during different parts of the night, hard to see it being useful. sigh

What are your T_min and T_max settings?

Ideally, your T_Max should be longer than most of your inhalations; if it is too short, yeah, the machine will switch from IPAP to EPAP before you are done inhaling on your longest inhalations.

Ideally, your T_Min should be shorter than most of your inhalations; if it is too long, the machine will stay at IPAP even though you have finished inhaling on your shortest inhalations.

johnydramachase wrote: ↑

Sun Dec 08, 2024 10:37 am

So auto S doesn't have this problem for you?

No AutoS seems to take the average of the last few breaths and settle to that....vastly easier to get on with which was frustrating as I am treading a fine line between sufficient difference between ipap and epap to address flow limitations and avoiding high levels of central so the back up rate (only available in a mode) would have been handy.

In the end the answer for me seems to be an EERS setup in autos which seems to be working

robysue1 wrote: ↑

Sun Dec 08, 2024 12:04 pm

johnydramachase wrote: ↑

Sun Dec 08, 2024 10:37 am

I've been playing with the t min and max settings and yeah it makes the exhale part longer, but it's like, I have to nail it perfectly to breathe somewhat normally. with nasal obstruction that varies from night to night and even during different parts of the night, hard to see it being useful. sigh

What are your T_min and T_max settings?

Ideally, your T_Max should be longer than most of your inhalations; if it is too short, yeah, the machine will switch from IPAP to EPAP before you are done inhaling on your longest inhalations.

Ideally, your T_Min should be shorter than most of your inhalations; if it is too long, the machine will stay at IPAP even though you have finished inhaling on your shortest inhalations.

I've been trying different T max and min, sometimes the IPAP gets cut short or the EPAP part does. Ti Min 2.0 and Max 2.7 seem to be a bit better for me. still needs experimenting. I wonder if I am cooked without the auto S mode

Have you tried s/t mode? I have a suspicion that this may be closer to auto s if you use the target tidal volume setting. From the literature this seems to react to your natural rhythm which is what auto s seems to do on the basic BIPAP machine. Would be great to confirm this either way.

johnydramachase wrote: ↑

Mon Dec 09, 2024 7:08 am

I've been trying different T max and min, sometimes the IPAP gets cut short or the EPAP part does. Ti Min 2.0 and Max 2.7 seem to be a bit better for me. still needs experimenting. I wonder if I am cooked without the auto S mode

Have you tried setting Ti_Min to be as small as possible and Ti_Max to be as large as possible?

If so what happens at those settings?

Garethep wrote: ↑

Mon Dec 09, 2024 12:37 pm

Have you tried s/t mode? I have a suspicion that this may be closer to auto s if you use the target tidal volume setting. From the literature this seems to react to your natural rhythm which is what auto s seems to do on the basic BIPAP machine. Would be great to confirm this either way.

I've tried it and there is no difference, it cuts the IPAP very short still. with 500 ml Target Vt or off, didn't see a difference

robysue1 wrote: ↑

Tue Dec 10, 2024 2:29 am

johnydramachase wrote: ↑

Mon Dec 09, 2024 7:08 am

I've been trying different T max and min, sometimes the IPAP gets cut short or the EPAP part does. Ti Min 2.0 and Max 2.7 seem to be a bit better for me. still needs experimenting. I wonder if I am cooked without the auto S mode

Have you tried setting Ti_Min to be as small as possible and Ti_Max to be as large as possible?

If so what happens at those settings?

Same thing, it switches to EPAP prematurely

johnydramachase wrote: ↑

Tue Dec 10, 2024 5:54 am

robysue1 wrote: ↑

Tue Dec 10, 2024 2:29 am

johnydramachase wrote: ↑

Mon Dec 09, 2024 7:08 am

I've been trying different T max and min, sometimes the IPAP gets cut short or the EPAP part does. Ti Min 2.0 and Max 2.7 seem to be a bit better for me. still needs experimenting. I wonder if I am cooked without the auto S mode

Have you tried setting Ti_Min to be as small as possible and Ti_Max to be as large as possible?

If so what happens at those settings?

Same thing, it switches to EPAP prematurely

The machine switching to EPAP prematurely might mean your Ti_Max is set for too short of a time, particularly if this is happening on most breaths.

If Ti_Max is set to 2.7, then the machine will switch to EPAP 2.7 seconds after it detects the beginning of the inhalation and goes to IPAP regardless of whether you are still inhaling. I would encourage you to consider setting Ti_Max to its maximum of 4, which would allow the machine to maintain the IPAP pressure for as long as 4 seconds when you are actively inhaling.

You also should consider the Cycle setting. Setting Cycle to Low or Very Low will make the machine "cycle" from IPAP to EPAP later in the transition from inhalation to exhalation. That will effectively delay the drop in pressure by just a bit on every single breath, and that might be just enough for you to feel like the machine is not cutting the IPAP too short.

If you also have problems with feeling like the machine is sometimes switching from EPAP to IPAP too early, you might want to play with the Trigger setting. Setting Trigger to High or Very High will make the machine "trigger" from EPAP to IPAP later in the transition from exhalation to inhalation. That will effectively delay the increase in pressure by just a bit on every single breath, and that might be just enough for you to feel like the machine is not cutting the EPAP too short.

johnydramachase wrote: ↑

Tue Dec 10, 2024 5:09 am

I've tried it and there is no difference, it cuts the IPAP very short still. with 500 ml Target Vt or off, didn't see a difference

That's a shame.....It may also be worth trying increasing target VT a bit and checking the backup rate is set sufficiently low that it's not forcing a cycle.

If that doesn't work then i'd probably recommending maxing out tmax and setting tmin to whatever is most comfortable (for me its about 2 to 2.3) you could also up the ipap pressure a little.

If it's any consolation, I did persevere and got used to the abrupt cut off after a few nights before I got the bits to set up EERS

Good luck

robysue1 wrote: ↑

Tue Dec 10, 2024 3:20 pm

johnydramachase wrote: ↑

Tue Dec 10, 2024 5:54 am

robysue1 wrote: ↑

Tue Dec 10, 2024 2:29 am

johnydramachase wrote: ↑

Mon Dec 09, 2024 7:08 am

I've been trying different T max and min, sometimes the IPAP gets cut short or the EPAP part does. Ti Min 2.0 and Max 2.7 seem to be a bit better for me. still needs experimenting. I wonder if I am cooked without the auto S mode

Have you tried setting Ti_Min to be as small as possible and Ti_Max to be as large as possible?

If so what happens at those settings?

Same thing, it switches to EPAP prematurely

The machine switching to EPAP prematurely might mean your Ti_Max is set for too short of a time, particularly if this is happening on most breaths.

If Ti_Max is set to 2.7, then the machine will switch to EPAP 2.7 seconds after it detects the beginning of the inhalation and goes to IPAP regardless of whether you are still inhaling. I would encourage you to consider setting Ti_Max to its maximum of 4, which would allow the machine to maintain the IPAP pressure for as long as 4 seconds when you are actively inhaling.

You also should consider the Cycle setting. Setting Cycle to Low or Very Low will make the machine "cycle" from IPAP to EPAP later in the transition from inhalation to exhalation. That will effectively delay the drop in pressure by just a bit on every single breath, and that might be just enough for you to feel like the machine is not cutting the IPAP too short.

If you also have problems with feeling like the machine is sometimes switching from EPAP to IPAP too early, you might want to play with the Trigger setting. Setting Trigger to High or Very High will make the machine "trigger" from EPAP to IPAP later in the transition from exhalation to inhalation. That will effectively delay the increase in pressure by just a bit on every single breath, and that might be just enough for you to feel like the machine is not cutting the EPAP too short.

Ti max goes up to 3 on this machine. I put it on Ti max 3 and min 2.2-2.1, still getting a feel for what's the least bad

I'm not sure what the cycle settings on this one is, probably the I sens and E sens?

Either way, I tried it on CPAP mode with the expiratory pressure relief (called Reslex) and it acts much more like I would like it to act, like it follows my breathing rather than controlling it for me as it does on the S mode. why can't it be like that but only with PS? is it specific to this machine?

johnydramachase wrote: ↑

Wed Dec 11, 2024 9:01 am

robysue1 wrote: ↑

Tue Dec 10, 2024 3:20 pm

You also should consider the Cycle setting. Setting Cycle to Low or Very Low will make the machine "cycle" from IPAP to EPAP later in the transition from inhalation to exhalation. That will effectively delay the drop in pressure by just a bit on every single breath, and that might be just enough for you to feel like the machine is not cutting the IPAP too short.

If you also have problems with feeling like the machine is sometimes switching from EPAP to IPAP too early, you might want to play with the Trigger setting. Setting Trigger to High or Very High will make the machine "trigger" from EPAP to IPAP later in the transition from exhalation to inhalation. That will effectively delay the increase in pressure by just a bit on every single breath, and that might be just enough for you to feel like the machine is not cutting the EPAP too short.

Ti max goes up to 3 on this machine. I put it on Ti max 3 and min 2.2-2.1, still getting a feel for what's the least bad

I'm not sure what the cycle settings on this one is, probably the I sens and E sens?

Yes, I_sens and E_sens would be the Trigger and Cycle settings. I've not been able to find a copy of the clinical manual for your machine on line. So there's a big question in how the E_sens settings would correspond to the Resmed Cycle settings. I am going out on a limb here and making a guess: My guess is that I_sens is the sensitivity setting used to determine the beginning of an inhalation and that E_sens is the sensitivity setting used to determine the beginning of an exhalation. (So I'm assuming that your machine's I_sens is Resmed's Trigger and that your machine's E_sens is Resmed's Cycle.)

It is worth checking: What are I_sens and E_sens currently set to? And what's the range of settings for each of those settings? (My guess is that both I_sens and E_sens are set to the middle of their ranges.)

And have you been able to get hold of the clinical manual for your BPap? (Apneaboard.com might be of help if you haven't.)

Either way, I tried it on CPAP mode with the expiratory pressure relief (called Reslex) and it acts much more like I would like it to act, like it follows my breathing rather than controlling it for me as it does on the S mode. why can't it be like that but only with PS? is it specific to this machine?

Reslex is supposed to mimic Resmed's EPR algorithm, which in turn is based on something Resmed calls "EasyBreathe" if I recall correctly.

On a Resmed VAuto or VPAP S running in VAuto or S mode, there is no EPR setting specifically because the basic algorithm for changing between IPAP and EPAP is based on the same "EasyBreathe" algorithm. The biggest difference between EPR on a Resmed AirSense APAP/CPAP and the "EasyBreathe" algorithm on the VAuto or VPAP S, is that the maximum PS for EPR is 3, whereas the maximum PS for the VAuto or S modes on a AirCurve can be much, much larger.

The other difference is that the Ti_Min, Ti_Max, Trigger, and Cycle settings on the AirCurve allow you to "tweak" or "fine tune" the basic EasyBreath algorithm so that the machine has an easier time following your breathing pattern.

Now, most people? They can't really tell any difference between EasyBreath on a Resmed AirCurve VAuto or S machine with PS = 3, Trigger = Medium, Cycle = Medium, and a Resmed AirSense APAP/CPAP with EPR = 3. But a few people can. In my case, when I first started out on a Resmed S9 APAP with EPR = 3, it consistently felt like the machine was switching to the higher pressure before I was done exhaling. And that was very irritating and it also caused me to swallow a lot of air. When I first got my current Resmed AirCurve VAuto, I noticed the same thing: With Trigger set to Medium, it still felt like the machine was increasing the pressure to IPAP before I was done exhaling. By switching the Trigger setting to Very High, that feeling disappeared.

I am pretty sure that the I_sens and E_sens settings on your machine act as ways to "tweak" or "fine tune" your machine's version of EasyBreathe so that it better matches your own breathing pattern.

Here's what I would suggest that you do:

Some afternoon when you have no intention of sleeping with the machine, go to your bedroom and mask up and lie down and simply breathe with the machine for at least 10-15 minutes. You want to breathe with the machine long enough so the bothersome feeling that the machine is trying to control your breathing kicks in and you have the time to really sort out which of these statements seem to be true. (More than one of them may be true.)

1) The machine seems to go to EPAP before you are done inhaling on your longest breaths.

2) The machine won't go to EPAP after you are done inhaling on your shortest breaths.

3) The machine seems to be encouraging you to exhale before you are done inhaling on most breaths.

4) The machine seems to be encouraging you to inhale before you are done exhaling on most breaths.


If #1 and/or #3 are happening, you will need to play around with the E_sens setting and/or the Ti_Max settings. First, I would recommend setting Ti_max to its maximum setting of 3. Next set E_sens it to its maximum setting and then turn the machine on, lie down, and breathe with the machine for at least 10-15 minutes. If the feeling that the machine is encouraging you to exhale is worse, then turn the machine off and set E_sens to its minimum setting and see if that is any better. There's a good chance that setting Ti_Max = 3 and E_sens to either its maximum or minimum setting will make things feel better.

If #2 is happening, you need to play around with the Ti_Min setting. I would recommend setting Ti_Min to the smallest possible value since that allows the machine to drop to EPAP when you finish a very short inhalation. Set Ti_Min to the smallest setting and then mask back up and breathe with the machine for at least 10-15 minutes and be sure to consciously take some extra short inhalations to see if the machine is doing a better job of switching to EPAP at the end of the exhalation.

If #4 is happening, you need to play around with the I_sens setting. After setting E_sens it to its maximum setting and then turn the machine on, lie down, and breathe with the machine for at least 10-15 minutes. If the feeling that the machine is encouraging you to inhale is worse, then turn the machine off and set I_sens to its minimum setting and see if that is any better. There's a good chance that setting I_sens to either its maximum or minimum setting will make things feel better.


I'll end with this: The reason that I suggest you do this experiment during the daytime, but in your bedroom while lying down is this: You want to be fully awake so you can pay attention to all the stuff that feels "wrong" at night and troubleshoot it. You should only make one adjustment to the E_sens and I_sens settings at a time, and after every change, you need to breathe with the machine in your normal sleeping position for at least 10-15 minutes while consciously paying close attention to whether the new settings feel better, worse, or about the same. You may want to write stuff down as you go so that if you make a change that makes things a lot worse, you have a written record of which settings felt best to you before you make the change that made things a lot worse.

Once you have found settings that seem to work reasonably well when you are awake and breathing with the machine, then do your best to try to not focus on your breathing when you mask up to go to sleep for the night. When we lie in bed trying to get to sleep, but we're preoccupied by over focusing on our breathing, that makes it a lot harder to get to sleep and it also makes every little glitch seem a whole lot more uncomfortable.

Good luck