Respironics BiPAP S/T: Need Help with Settings

jdetray · Post by **jdetray** » Fri Feb 22, 2008 10:50 am

I've received my new Respironics BiPAP S/T from my DME. Their young RT has little experience with this machine, and there is something wrong with the setup. Not having the provider manual, I'm don't know which setting is incorrect. I'm hoping one of you can provide some guidance.

My basic settings are IPAP=14, EPAP=8, and BPM=18. Here's what's happening.

It all seems fine as long as I'm taking spontaneous breaths, but when the machine generates a breath, there is a problem. (The machine displays pressures in real time, so I can see what is happening.)

During a machine-generated breath, it appears that as soon as the pressure reaches 14, the machine instantly switches to EPAP. It does not sustain the IPAP (14) long enough to inflate my lungs. Out of each 3.33 second cycle (18 BPM), it stays at 14 for only about 0.5 seconds, not nearly long enough. My old S/T machine remains at 14 for about 1.5 seconds.

My impression is that there must be a setting that causes the machine to switch to EPAP as soon as the IPAP pressure is reached, whereas it should sustain the IPAP pressure for long enough to inflate my lungs.

The result is that after 2 or 3 machine-generated breaths, I'm starved for air and must start breathing on my own. Needless to say, I can't sleep this way!

I think I know how to get the machine into provider mode (I watched the RT very carefully), but I don't know what I'm looking for.

Does anyone know the name of the setting or settings that could be changed to resolve this problem?

I can (and probably will) go back to the RT, but I'd at least like to go armed with enough information to explain this in the proper technical terms.

Thanks,

Jeff

dsm · Post by **dsm** » Fri Feb 22, 2008 2:00 pm

Jeff,

I have a Bipap S/T I can test out but I never used it because of a very similar problem. I did manage to get it running sort of ok but will have to look at it to see if I can recall the settings.

This machine was going to be my primary cpap - it is still new with only a few hours on it. The machine is very nicely built.

Will have a look at it today (is am here) & get back to you.

DSM

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): bipap, CPAP

mch441 · Post by **mch441** » Fri Feb 22, 2008 2:47 pm

i have a repironics bipap plus which i guess is just the cheaper version of what you have .i have played around with mine a bit and it sounds to me like the biflex setting it can be set from 0 to 3. at 0 or 1 for me felt like a switch being flipped between epap and apap and at 3 which is what i set mine on it feels like im barely breathing against the machine at all very comfortable and the readout will hit the max then fades back ,my machine is set at 10 and 15

Guest · Post by **Guest** » Fri Feb 22, 2008 4:25 pm

The screen you are looking for in the provider menu is the Inspiratory Time setting. It will say INSP. in the lower righthand corner, the range is 0.5 sec to 3 seconds, you can set it in 0.1 sec increments. They should have put you on the machine in the office and had you breath on it at different IT settings until it felt comfortable to you.

Disclaimer:
I don't recommend that you change this setting yourself, I would take it back to the RT armed with the information that you have recieved here.

dsm · Post by **dsm** » Fri Feb 22, 2008 4:29 pm

Jeff PM sent,

DSM

dsm · Post by **dsm** » Fri Feb 22, 2008 4:33 pm

Jeff,

Once current settings are saved & noted. Try setting INSP = 3.0 then start reucing the BPM from 18 down. Go straight to 12 BMP as the starting point. Don't go below about 8 unless you have spoken to your RT.

Good luck

DSM

#2 Ps I was running my rise time at 6. Also be aware that BiFlex doesn't operate unless in S mode so won't be available in S/T mode - also this machine doesn't provide AHI nightly data but does give a summary AHI for the night.

(PS despite what I just told you - I was running mine at 6 BPM to get it to work best but I would need more input before recommending this)

Guest · Post by **Guest** » Fri Feb 22, 2008 4:40 pm

DSM is correct, you must reduce your BPM rate if you want an Inspiratory Time of 3 sec. At BPM setting of 18 you can only get it too 1.15, the machine will not do inverse Inspiratory:Expiratory ratios. It will always reduce the IT to keep the I:E ratio at 1:1.

dsm · Post by **dsm** » Fri Feb 22, 2008 4:48 pm

Some info on how the Bipap S/T cycles between ipap & epap & ipap ...

Sensitivity: There are internal algorithms for ...
- Volume Trigger (trigger based on volume of air breathed in)
- Shape Signal (trigger based on the waveform shape}
- Spontaneous Expiratory Threshold (SET)

1) Volume Trigger = 6 ml of accumulated inspiratory volume

2) Shape Trigger / Shape Cycle = triggers ipap & cycling from ipap to epap. Tracks inspiratory and expiratory flow & adjusts spont trigger and cycle thresholds for optimum sensitivity.

3) SET = used to cycle off ipap. This rises in proportion to the inspiratory flow rate on each breath. When SET and actual patient flow values are equal, the unit cycles to EPAP

Leaks will skew any of this data. The machine tries to estimate leaks but it is a challenge when there is no additional mask pressure sensing being done.

Good luck

DSM

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): bipap

jdetray · Post by **jdetray** » Fri Feb 22, 2008 6:00 pm

Thanks much for the replies.

I don't want the Inspiratory Time to be 3 seconds. On my old machine, it is about 1.5 seconds, and I am happy with that.

I have not yet put the new machine into clinical (provider?) mode to look at the settings. However, I have done some crude timing with a stopwatch. Here's what I have found.

When I stop breathing on my own and depend on the machine to initiate a breath, the display shows the pressure rises quickly to my IPAP of 14. So far, so good. But after only about 0.6 seconds, it drops to my EPAP of 8 and remains there for about 2.7 seconds. The cycle then repeats. This works out to 18 BPM, which is correct. This I:E ratio is about 1:4.5.

The short time at IPAP is far too short to give me a full breath. My lungs just barely begin to fill before the pressure drops back to EPAP. After 2 or 3 of these short, inadequate breaths, I start to feel out of breath and must consciously start to breath on my own to catch my breath.

Will adjusting INSP improve this situation? Is bringing the I:E ratio closer to 1:1 what needs to be done?

On my old-style BiPAP S/T, the I:E ratio is close to 1:1. This old machine has four knobs on the back: IPAP, EPAP, BPM, and %IPAP. These are the only adjustments available on the machine, and they are set to 14, 8, 18, and 45%. This old machine is still working, but it's old enough that it could fail at any time, which is the whole point of getting the new machine.

Thanks,

Jeff

dsm · Post by **dsm** » Fri Feb 22, 2008 6:36 pm

Jeff,

The BPM of 18 is just too high.

Good luck with this

DSM

jdetray · Post by **jdetray** » Fri Feb 22, 2008 7:42 pm

dsm wrote:The BPM of 18 is just too high.

I don't agree. For the past 20 years, I've been on a BPM of 20, and it's been great. The new BPM of 18 is as a result of my recent sleep study and is less than the 20 I've been on since 1988!

- Jeff

dsm · Post by **dsm** » Sat Feb 23, 2008 4:31 pm

jdetray wrote:
dsm wrote:The BPM of 18 is just too high.
I don't agree. For the past 20 years, I've been on a BPM of 20, and it's been great. The new BPM of 18 is as a result of my recent sleep study and is less than the 20 I've been on since 1988!

- Jeff

Jeff,

I meant it is too high for you to change the INSP. See akcpapguy's post.

When in Timed mode, the BPM will overide anything you set the INSP to.

Good luck with your adjustments.

DSM