VPAP Spontaneous Triggered & Cycled Breaths

[airbusA346]

Hi,

I was switched onto a Resmed Lumis 100 VPAP ST-A (ST Mode; I: 23.0, E: 7.0) the other day from a Respironics System One APAP.

And two pieces of information in the sleep report are "Spontaneous Triggered Breaths %" and "Spontaneous Cycled Breaths %".

Can someone explain what they mean, because I want to figure out how much work my VPAP is doing for me... A little or a lot.

My percentages for the last two nights (same on both nights) were 11% for Triggered and 39% for Cycled.


Thanks


Tom.

[Matt00926]

Spontaneous trigger percentage is the percent of breathing where you had a spontaneous breath, meaning that you triggered the IPAP/initiated the breath yourself, not the machine. 

My guess is that the backup rate they set is very high, probably just at or maybe 1-2 bpm below your spontaneous breathing rate. That is designed to help people with muscle weakness in the diaphragm, allowing the machine to do most of the work so you can rest. Also to increase your minute ventilation to blow off carbon dioxide. I assume this is why you were prescribed the ResMed Lumis?

[airbusA346]

Spontaneous trigger percentage is the percent of breathing where you had a spontaneous breath, meaning that you triggered the IPAP/initiated the breath yourself, not the machine. 

My guess is that the backup rate they set is very high, probably just at or maybe 1-2 bpm below your spontaneous breathing rate. That is designed to help people with muscle weakness in the diaphragm, allowing the machine to do most of the work so you can rest. Also to increase your minute ventilation to blow off carbon dioxide. I assume this is why you were prescribed the ResMed Lumis?

My bpm backup rate is set to 15.

Yes it's because my carbon dioxide levels were too high.

So have I initiated 11% of the breaths?

What's the difference between the triggered and cycled breaths?

Sorry for all the questions... I understood my APAP data etc, but some of the VPAP stuff is throwing me.

[Matt00926]

My guess is that when you are awake and before you fall asleep, your respiratory rate is slightly above or equal to 15bpm - which is where most of the 11% spontaneous triggered breaths comes from. When you fall asleep, most likely your respiratory rate decreases, except for maybe during moments of hypopnea or hypoventilation, meaning that timed machine breaths occur.

During spontaneous breathing on S/T mode, the user mostly drives the respiratory rate and inspiratory time (how long the inhalation part lasts). During a timed breath, the machine creates a breath if you breathe at a rate below the backup rate. I don't think the ResMed device forces the backup breath to have a specific set inspiratory time like Respironics machines do in S/T mode - with ResMed machines you just have the range of Ti Min and Ti max and those apply to all breaths - spontaneous and timed.

Cycling is a window of time in which the device switches from IPAP (breathing in) to EPAP (exhaling). If the cycle is set to a low sensitivity, it will make the inhalation portion of the breath cycle longer, and delay expiration (helpful in restrictive lung disease/neuromuscular disease). Conversely, if the cycle sensitivity is high, the inhalation will terminate more quickly and switch over to exhalation (helpful in obstructive lung disease).

The VPAP is a ventilator so it is much more complex than an APAP - hence all the mumbo jumbo terminology .

[Sleeprider]

Matt did an outstanding job of explaining trigger and cycle and how your machine is performing its backup rate functions. From your profile it appears you are using an IPAP of 23 cm and EPAP of 7.0 cm for a pressure support of 16 cm. That pressure support is how the machine triggers a breath when you don't spontaneously initiate an inhale. Expiration is passive, and the machine cycles to the lower EPAP pressure allowing you to exhale.

You were switched from a Respironics APAP machine to the VPAP ST-A, and that is a pretty remarkable change. Did you have central apnea previously, or was your problem an inadequate respiratory tidal volume? Was a bilevel (VPAP/BiPAP) without the backup rate tried during the titration? How are you feeling so far with the new therapy?

Welcome to Apnea Board. Hopefully we can help answer your questions and support your use of the new machine.

[trish6hundred]

Hi airbusA346,
WELCOME! to the forum.!
Good luck as you continue CPAP therapy.
You have come to the right place for guidance, hang in there for more responses to your post.

[airbusA346]

Matt did an outstanding job of explaining trigger and cycle and how your machine is performing its backup rate functions. From your profile it appears you are using an IPAP of 23 cm and EPAP of 7.0 cm for a pressure support of 16 cm.  That pressure support is how the machine triggers a breath when you don't spontaneously initiate an inhale.  Expiration is passive, and the machine cycles to the lower EPAP pressure allowing you to exhale.  

You were switched from a Respironics APAP machine to the VPAP ST-A, and that is a pretty remarkable change. Did you have central apnea previously, or was your problem an inadequate respiratory tidal volume?  Was a bilevel (VPAP/BiPAP) without the backup rate tried during the titration?  How are  you feeling so far with the new therapy?

Welcome to Apnea Board. Hopefully we can help answer your questions and support your use of the new machine.

Looks like my machine is doing a lot of work then.

I had been on APAP since October 2014 for OSA and have needed high pressures from the start... 17-18 etc.  After about 6 months on APAP I had been complaining to my consultant that something wasn't right... still tired, not feeling like I'm getting refreshing sleep, still snoring etc, falling asleep in the evenings.  He wouldn't consider 'looking outside the box' (or at different machines) at things like CO2 levels during the night.  He did organise a blood gas test, but that was done 4 hours after I had got out of bed.  So a useless result.  

So in November (2017) I finally had enough of being ignored (numerous letters backwards and forwards), so took some advise and recommendations and saw a consultant in London (several hours away from my home), who straight away listened to my concerns and problems.  At the end of the consultation he said that ventilation might be the way to go, because of my high pressures.  A overnight TOSCA was organised, which showed raised CO2 levels.  Being switched to a different machine was 90% there, but they wanted to do a polysomnography with TOSCA to just make sure.  This was done on Wednesday and the next morning I was told that I would be switched to a ventilator due to my high average CO2 levels through the night and the high APAP pressures I require.

So I came home with my new Resmed VPAP and to be honest I'm over the moon. 

[SarcasticDave94]

Welcome to the Apnea Board and congrats on your new machine. I'm guessing it's doing well in providing great therapy.

[Sleeprider]

Airbus, you have been under some very specialized care, and if you're feeling better, that is usually a good indicator of the effectiveness of the treatment. At 23/7 pressure, you should be feeling the benefits of a much improved ventilation rate. It's apparent your obstructive apnea is responsive to the lower EPAP pressure of 7, and that your IPAP pressure of 23 helps you to fill your restricted lungs to capacity and reduce CO2. We don't have many members with your specific problems, and the solution of using high pressure support to resolve a CO2 buildup. This is without doubt going to be very beneficial to how you feel and cope with your COPD. I hope you'll stick around and help others that may arrive with similar issues, and in need of navigating the medical system to get proper treatment. We have a number of U.K. members, and it seems to be quite a challenge when something is "outside the box" of normal expectations.

[Matt00926]

Airbus:

While you are awake, is the device itself comfortable? When you try to breathe in, does it trigger a breath/inhalation properly in sync with your breathing?

Another reason for possible machine triggered breaths, aside from breathing below the set backup rate, is that the "trigger sensitivity" is too low and so the machine does not sense you trying to take a breath, so the machine does it for you. This is just a possibility, and the setting may not need adjusting. But, while awake if you do breath in, and nothing happens, then trigger definitely does need adjusting. This is harder to tell if it's happening when you're asleep, well, because you're asleep lol.

If the inhalation portion feels too short, meaning you are trying to inhale but the machine cuts out, then you can lower the cycle sensitivity or increase the Ti Min setting (or both).

Depending on the severity of your scoliosis, especially if you have a kyphosis curve as well, this would in effect be called a chest wall disorder, which is an extrapulmonary (meaning it's a mechanical problem, not your lungs themselves) restrictive disease because the curvature compresses the lungs in a way that makes them difficult to expand properly. That process overtime causes issues with ventilation, hence the retention of CO2.

The only reason I know the above is because I suffer from that exact condition .