Low pressure support alarm in BIPAP AUTO SV

[ChrisT]

During the last week I have been awakened by an alarm that states "low pressure support". What would be the most common reasons for this? I have been on the same settings for months.

[2 B Sleeping Soundly]

ChrisT,

You might want to add ASV to your Subject title. You are among a more select group here who use this machine and deal with specialized settings and issues. Adding ASV will flag your post for those who are very knowledgeable in this area.

John

[Pugsy]

It has to do with something that the ASV machine is sensing that is below the warning threshold.
It is sensing something it doesn't like but I couldn't find out exactly what by reading the provider manual.
There are a couple of alarm features mentioned but it didn't say which one gave that message.
Hopefully and ASV user can explain it better.

[JohnBFisher]

During the last week I have been awakened by an alarm that states "low pressure support". What would be the most common reasons for this? I have been on the same settings for months.

Yeah, this is the one thing that I really, really **HATE** about the PR System One ASV unit. I have *NOT* been able to find a way to turn off this alarm.

There are two reasons that I know that you might be getting this alarm. The most common is that if the mask is leaking then it will not be able to reach the desired pressure when you need it. For example, if you stop breathing (due to a central apnea), it will quickly ramp up the pressure to help sustain respiration (that's the "ventilator" part of "adaptive servo ventilation" or ASV). If, due to the leak, it can not attain that desired maximum pressure, the "low pressure support" alarm fires.

The other reason you might get this alarm is that the unit simply can not push against you hard enough. This might occur if you are on your back and you are definitely overweight. Then as it ramps up the pressure it is not able to move enough air to attain the pressure support it wants. Typically it will leak as a result. In this case, if you are on your side it will do better.

I've not fully resolved this problem. For me, it's REALLY frustrating, since I stop breathing as I fall asleep. So, just as I fall asleep, I have central apneas (due to the sleep state transition). And just as I fall asleep that bloody alarm kicks off. Generally, I'll go to where I have my other (Resmed) ASV setup and use it. It's easier than having that alarm kick off.

However, if you sleep on your side, you might not have as many problems. You might also benefit from dropping the maximum pressure (for example from 25cm H2O to 20cm H2O). I suspect, but have not tested this, it will help reduce that problem.

Hope that helps.

[ChrisT]

Thanks John Fisher for that in depth reply. It has given me some food for thought. I don't think it is positioning and it is not weight. I do and more so lately stop breathing as soon as I fall asleep and it takes more to get started breathing again. I also have a condition where the vocal chords slam shut on occasion and nothing can blast through so BIPAP and oxygen are temporarily not able to ventilate. I will have surgery for that in the spring. That tho usually results in higher overall pressures. So it could be a leak....or the going apnic for longer periods of time if I understood all you said. ChrisT

[JohnBFisher]

Thanks John Fisher for that in depth reply. It has given me some food for thought. I don't think it is positioning and it is not weight. I do and more so lately stop breathing as soon as I fall asleep and it takes more to get started breathing again. I also have a condition where the vocal chords slam shut on occasion and nothing can blast through so BIPAP and oxygen are temporarily not able to ventilate. I will have surgery for that in the spring. That tho usually results in higher overall pressures. So it could be a leak....or the going apnic for longer periods of time if I understood all you said. ChrisT

Yup. Due to a neurological problem, I suspect I have vocal cord paralysis on occasion. On bad days, I loose all tone in my voice. The only thing that is left is the syllabant and gutteral sounds. So, I hear what you are saying. I know that when I'm having a "bad day", I tend to hear that bloody alarm over and over as I try to fall asleep.

So, your vocal chord problems might trigger the same pressure alarm. It might be saying, "I've increased the pressure but there's still an apnea". All that I know for certain is that the bloody alarm almost always goes off as I'm falling asleep.

Since you have vocal chord problems, you are probably also aware that the only sure cure for problems with the vocal chord is a tracheostomy. Ugh! I really hope the surgery helps you.

Sadly, as my situation continues to deteriorate, I will probably have to shift to a ventilator to get the pressure support that I need. The difference between an ASV unit and a ventilator is that the ventilator WILL be certain that I get the pressure requirement that I need.

[ChrisT]

John, sorry to hear that you too have some vocal problems too. The more I use my voice the more I note a change in tone and tremor so by the end of the day or a long conversation mine is shot. Mine should be fixed by a surgery that whittles down the muscles and that is called a myotomy. It is not that invasive and can be done through a scope. It took a long time to diagnose and often mimcs asthma and causes some dysphasia. Finally I found an ENT who recognized the pattern although he is in another state. I have actually had the vocal chords slam shut when I am awake during a PFT. Odd feeling that one. IT could very well be the problem here as you point out. I appreciate your expertise on this. I will ask my pulmonologist about lowering the one pressure as maybe that will help with the alarm. I hate being awakened by it. ChrisT

[ChrisT]

I thought I posted this but looks like I didn't.....Lack of sleep for sure...Anyway...my surgery that will fix the problem is done through a scope and involves whittling down muscles that are hypertrophied so they can work properly. It took a long time to get diagnosed and I finally was by a very good ENT at a major medical clinic out of state. This often mimics asthma and causes dysphasia and problems with swallowing as well as the snapping shut of the vocal chords on occasion. It can cause a very odd pattern on BIPAP. These snapping shut episodes often cause increased AHI and higher pressures. Anyway....I will contact my pulmonologist about possibly changing pressures to handle this alarm. Sleep....above all.....uninterrupted sleep is the goal.

I appreciate all that commented. ChristT