[Equipment] Settings on Resmed st-a IVAPS

[mommadavis]

Thank you both for responding. I am fine with my IVAPS until I try to go to sleep. Once I start to fall asleep, it still kicks out two or three faster and stronger breaths. So, then it wakes me up. I get frustrated and then move back to my Bipap which is the vAUTO. Grrr. I have read through everything and made several adjustments and it isn't as strong, but it still does it. I am open to any suggestions. Here are my current settings: 

mode: IVAPS
Target PT rate 12
Target VA 3.0L
MV 4.2 L (this is changed with any changes to VA)
VT 354 ml (this is changed with any changes to VA)
VT/kg 5.9 ml (this is changed with any changes to VA)
EPAP 6.0
Min PS 4.0
Max PS 12
Ti Max 2.0s
Ti Min .3s
Rise Time 350 ms
Trigger low
Cycle very low

I inserted both cards and it may have confused Oscar because it shows vauto as the machine. Tried to delete some data and redo with the IVAPS but still says vauto. Anyway.... Here are my reports. 

This is the report from the Vauto from last night:

   

This is the IVAPS from Monday after more hours than normal, but still not sleeping. 

   

I also calculated my tidal volume to:
354 ml, IBW 59 kg if 6 ml
472 ml, IBW 59 kg if 8 ml

Like I mentioned above, if I adjust the VA, it adjusts those 3. I can't independently control them. There is no auto feature either.

[Sleeprider]

Your chart does not confirm your perception that once you fall asleep the machine "kicks out two or three faster and stronger breaths. So, then it wakes me up".  The chart below shows that pressure support and respiration rate are nearly constant at each therapy break except perhaps at 03:20.  I'm sure you are feeling something, but it's not showing up in the data.  It might help to zoom in on the moments before the therapy break or sleep disruption.  PS remains at 4.0 and the respiration rate is consistently high enough that the machine's breath rate backup should not be kicking in.

[StuartC]

As you say, both your charts report as the VAuto machine.  If you are using both machines in the same night, perhaps try creating different profiles for each machine to make sure there is no confusion between them.  Import each SD card into each of the different profiles.

One thing I notice from your charts is that you have no obstructive apneas, few hypopneas and mostly or all central apneas.  So the first question I must ask is whether the ST-A machine with iVAPS mode is, in fact, the correct machine and mode for you, or whether an ASV is more appropriate.  

The next thing I need to ask is what your underlying objective is?  I note that you said in your original post that you have "shallow breathing", which leads me to anticipate that you would like to increase your tidal volume.  Tidal volume is generally increased by increasing pressure support, but you can do that with either the VAuto or the ST-A machines in VAuto, S, ST or iVAPS modes.  So let's first explore the modes a bit.

• With VAuto, the min EPAP (Expository Positive Air Pressure) is set to overcome obstructive apneas (OAs), but it is increased by the auto algorithm if OAs, flow limits or snore occur.  It has a constant PS (Pressure Support) added to determine the IPAP (Inpository Positive Air Pressure, IPAP = EPAP + PS).  The change between EPAP and IPAP is determined by detection of your spontaneous breathing.
  

• With S mode, both the EPAP and IPAP are fixed.  The PS is simply the difference between them (i.e. PS = IPAP - EPAP).  The pressure change between EPAP and IPAP is determined by detection of your spontaneous breathing.
  

• ST mode is the same as S Mode except that the change between EPAP and IPAP is determined by detection of your spontaneous breathing only if you are breathing at a rate faster than the backup rate, which can be either fixed or variable if you are using "intelligent" backup rate (iBR).  If not, the change from EPAP to IPAP is triggered automatically at the backup rate.  The change from IPAP to EPAP is prevented for the duration of Ti min and occurs automatically if it has not already happened spontaneously before Ti max.
  

• iVAPS is similar to ST mode. The difference is that PS is variable, not fixed.  The purpose of varying PS is to achieve an "assured" (i.e. specified minimum) volume. 
  

• iVAPS can also be similar to VAuto, with the addition of backup rate and variable PS, if Auto EPAP is enabled.  However, there is a possible problem with the AutoEPAP option because MaxEPAP cannot be less than 8 (experience from my machine, not something I have found to be documented.  Perhaps this is not true for your machine). 
  

Now, you might think that iVAPS is the perfect mode if your objective is to obtain a particular tidal volume.  But is is not used often because (1) it is complex, (2) it leads to rapid pressure changes and (3) it is not often necessary because perfectly good results can be obtained with S or ST modes.  For example, the reason iVAPS is correct for me is that my minute vent changes during the night (it drops by 40 to 50% during REM) so the min PS (that I could apply in S or ST mode) works fine during non-REM but is not sufficient during REM.  My SpO2 follows my Mv - and keeping that above 90% that is ultimately what I want to achieve.

Looking at the charts that you provided:

1. You had no obstructive apneas and your pressure barely changed throughout the night, so I would suggest that you probably do not need an algorithm that auto adjusts EPAP.
   
2. Your respiratory rate, tidal volume and minute vent trends were all reasonably steady for the whole night, so you might not need auto adjustment of PS.
   

So I am going to suggest that you try the following settings on your ST-A machine:

Mode: ST
IPAP: 10 (increase this if your Mv or Vt is lower than you need.  Refer to your median values in the left panel if your chart trends are approximately constant)
EPAP: 6  (so PS = 4, while IPAP = 10)
iBR: On
TPR: 12 (this sets your min RR to 8)
Ti Max  -  Check the setting on your VAuto, it should be the same as that
Ti Min  -  Check the setting on your VAuto, it should be the same as that
Rise Time - You do not have a Rise Time setting on the VAuto so the trick here is to zoom right in on your mask pressure for the VAuto and the ST-A and adjust Rise Time to make the shape of increase in the pressure wave look the same.  This is possibly the maximum value that can be set relative to Ti Min (bacause it cannot be as long as or longer than Ti Min)
Trigger  -  Check the setting on your VAuto, it should be the same as that.  Otherwise Medium.
Cycle  -  Check the setting on your VAuto, it should be the same as that.  Otherwise Medium.

Oh, I must point out that I am working off the clinical guide for the Lumis 150 ST machine.  It is a little different to yours as I do not have ST-A mode, but ResMed did confirm for me that the "-A" simply refers to alarms, not therapeutic function, so I think I have what I need.  If I do say something that you do not have in your machine, please let me know. 

Getting ST mode working first is one step in the strategy that I used to get iVAPS working.  I used ST mode to determine the effects of changing:

• IPAP
  
• Fixed backup rates
  
• Target patient rates when using intelligent backup
  
• Rise Time and Ti Min
  
• Trigger and Cycle 
  
• Different masks
  

To monitor the effects of each change (only one at a time, for a couple of nights then I reversed the change), I found I needed to track the rates of spontaneous trigger and cycle.  Unfortunately, these are not reported in OSCAR so I do the following:

1. View the Sleep Report on the machine.
   
2. Make sure the reporting period is set to "Daily"
   
3. Scroll right down to the bottom of the list to see the values
   
4. Record them in a spreadsheet - along with all of the settings or other changes.
   

Once I had my best ST mode settings configured, I switched to iVAPS with target volumes less than my typical volumes but set to trigger the increase in PS when needed (I used Mv to determine this).  I initially set my PS max to be 1 more than PS min and increased from there as necessary.  If you do need (or want to try) iVAPS mode, perhaps this will work for you too.

I hope this information and these suggestions help.  I am mindful that I am working from my personal experiences, which will be different to yours because our underlying conditions are not the same.  But certainly, a PS range from 4 to 12 would be the stuff of nightmares to me, so I am not surprised that you are finding iVAPS difficult as you have it set.

[mommadavis]

Thanks for your replies. I switched to IVAPS because I have a neuromuscular disorder that fluctuates and it is the recommended machine for NMD. My Bipap was great most of the time, unless my diaphragm was really weak and it didn't help much. So my goal is to have a machine that can adjust to my weakness. I have an appointment on Wednesday with a therapist that is supposed to be an "expert" with this machine. I'll see what she says and even asked about switching to ST mode. I don't really understand the difference. I also do not have auto epap option with this machine. I plan to go in today and erase the data and start over and only do the ivaps data. When my diaphragm is weak, I have too much CO2. My lungs feel squeezed and I can't take deep breathes. I sleep upright most of the night. I use the machine throughout the day, as needed, too. I have not been able to sleep at all with it, so all of my data is when I'm awake. I'll check back in later this week once I run the reports again and speak with the therapist. I also plan to ask if the vauto was still OK but just needed to have settings adjusted. Very frustrating when the people you count on to know the machine, have no idea. I appreciate this group and your help.

[StuartC]

If this therapist is a specialist with iVAPS, make the most of it because few people seem to be. It will be fantastic if you do get the support that you need.

The key word that I saw in your reply was "fluctuates". While I did not see much fluctuation in the charts that you posted, I am guessing that it might occur night-to-night rather than within a single night. iVAPS should be good at responding providing you can measure / quantify your weakness in terms of volume and state your therapy objective as a specific target volume, whether that be expressed in terms of Va, Mv, Vt or volume/kgIBW. Beware, however, as soon as your volume drops even a little below the target, PS will increase quite rapidly. For example, my Mv target is 5.3 L/min and I am seeing a 2 cmH2O increase in PS when Mv appears to be in the range of 4.9 to 4.7 L/min (a decrease of 400 to 600 ml).

ST mode will not respond to fluctuations in the same way. But it may still work just as a stepping stone to getting iVAPS working. If you are able to use this when your diaphragm is not weak, you will hopefully gather good data to set min PS, TPR and Target Va for iVAPS.

Good luck with the appointment.

[mommadavis]

I think this is a better report. I removed the other data and it's just the ivaps now per your advice. I'll check back after my appointment tomorrow. Thanks again for the help. 

   

[mommadavis]

So, I think the settings the therapist changed are making things better. She increased my Target PT rate to 14, but I ended up dropping it to 13 because I felt like I was breathing too fast. Target VA increased to 4.0, Rise Time to 300 and ti max to 2.3 and min .6. Trigger and Cycle set to low. I also switched to a different mask. I really love my nasal pillow mask airfit N30, but she said it wasn't made for this type of machine and suggested I switch to the F&P Evora. I'm getting used to it, but don't hate it like I did at first. I might just need a bigger size. My other nasal mask is a small, so she got me a small, but it might be too small. Anyway... I actually got 6 hours in and slept a little with these new settings. What I don't know is what helped the most. I suspect it's the PT rate. It was mentioned in this feed that it will kick in the backup breath when it drops below the PT rate within 2. So I had it set on 12 and now it's 14. No idea. I'm more hopeful. Here's my report from my best and longest time. I think the hardest thing for me to get used to is it seems to initiate breathing way more than my bipap ever did. I can feel it. It's not actually breathing for me, but it can feel like it at time. I think that's part of my adjustment.  Last night my diaphragm froze and it really worked to help me through it.

Thanks again for the help and great advice!  

   

[StuartC]

I think you are not understanding Intelligent Backup Rate (iBR) correctly.  The idea is to set the rate that you should be breathing at, or above (TPR = 14, according to your therapist).  The machine will let you breathe spontaneously for as long as your respiratory rate (RR) stays above two thirds of the TPR.  ResMed call this the "Background Rate".  So, with TPR = 14, it lets you breathe spontaneously as long as your RR stays above 9.33 bpm.  If your RR drops below that, it will increase your RR to 14, and it will do this within 4 or 5 breaths.   If you do not attempt to breathe spontaneously at a rate faster than 14 bpm, it will continue to trigger breaths at that rate.  However, as soon as you breathe even a singe breath at a rate faster than 14, it will reset and go back to monitoring for RR < 9.33.

If TPR was set at 13, the backup Rate would have been 8.67.

The reason I describe this is because you had a lot of breathing at a RR faster than 14,  That was entirely spontaneous, iBR had nothing to do with it.  It is a little difficult to see exactly where 9.33 is on the chart, but most of the time, I think you were well above that.  It is a little easier to see where 8.67 is on the chart and your RR does appear to have dropped that low sometimes.  But you very soon spontaneously increased your RR each time and it does not appear, to me, that your rate of spontaneous trigger or cycle is all that low?  Or would be with TPR set at 14.  Did you perhaps check it on your machine as I described in a previous reply?

It is interesting that she set both trigger and cycle to low since the ResMed titration guide actually suggests that trigger should be high.  But then, the guide is just that for a reason - it is a starting point.

I would actually suggest that the new settings are doing better because it is increasing pressure more often - and when needed.  That is a function of the increased Va setting.

I'm glad that you have had a good experience.  Therapists who know and understand VAPS are rare, so I think you were quite lucky to find her.