resmed vauto spontaneous cycle

[sheepless]

the resmed vauto reports a percentage for spontaneous cycle.  if I recall correctly it's based on the last 15 or 20 breaths. oscar doesn't report this stat so there's no way I know to monitor it other than waking and looking.  on the few occasions I've noted it, it's usually around 90 or 92% but I've seen it as low as ~75%.

1. what does this metric tell us?  (I assume it's at least a loose indicator of central apnea?)

2. does anyone have an idea how to use this information?

3. does anyone know at what percentage one should pay attention to this stat and follow it up some how?

4. I'm curious what percentages all you other vauto users see...

[DorMindo]

Old thread. I think spontaneous cycle is the breaths you take within the minimum and maximum inspiration time (Ti Min and Ti Max) that can be configured in the Vauto model (and probably other models). If the time you take is outside these boundaries the breaths are not considered "spontaneously cycled" by you.

The presentation of some Resmed devices explains TiControl as to be used by patients with some lung pathologies and together with Vsync to keep synchronization in the presence of leaks.

My inspiration time falls within the default 0.?-2s range of the device, but sometimes when Im awake it is above 2s, I changed the Ti Max to 3s because its anoying when the device try to force a cycle when Im trying to calm down taking longer breaths. Now my breaths are almost 100% spontaneous and this is the same behaviour as an Autoset model. I did not found any use for this, I don't have any known lung problem and I almost don't have any leaks either.

[sheepless]

thanks for your response; I was disappointed this topic fell through the cracks. I think your explanation is consistent with my guess that it's an indicator of tendency for central apnea but idk.

I too set my timax to 3 - because I felt my inhale was cut off too often. I haven't investigated very carefully but I believe I still get low % (like in the 70's and 80's) occasionally even though I don't think my inspiration time exceeds it in the stats. I'll be returning to vauto soon so I'll try to pay more attention to this.

anyone else have knowledge or an opinion about this?

[StuartC]

This is an old thread indeed.  The low number of responses is, I presume, an indication of how little trigger and cycle is considered or changed.

Firstly, I use an iVAPS, which reports both spontaneous trigger and cycle in the sleep report on the machine, but not into OSCAR.  What I am trying to learn about is the significance of low spontaneous rates, and also how to determine appropriate settings for T Rise, Ti Min and Ti Max.

I thought I should start with what I understand about Trigger and Cycle.  Please correct me if I am mistaken in any way.

Trigger is the event that initiates change from EPAP to IPAP.  The setting in the machine is the sensitivity applied to the detection of this event being initiated spontaneously.  A setting of high / very high means that pressure will change in response to detection of little to very little effort to inhale. Low / very low requires quite some effort to inhale to be detected before pressure is changed.

Non-spontaneous triggering only applies to modes that have timed backup rates.  If, for example, the backup rate was 12 bpm, the duration of each breath could not exceed 5 seconds.  So if the user initiates inhalation within within 5 seconds of the previous breath, that is spontaneous.  If the user does not trigger inhalation within  5 seconds, the machine will trigger instead and that is non spontaneous.  The % spontaneous Trigger is then the number of spontaneously initiated inhalations divided by the total number of breaths, expressed as a percentage.

My personal experience with reduced % spontaneous trigger was that it appeared to be indicative of low CO2 / over-ventilation.  I'm not sure that would necessarily be an indication of CAs, except that I have few OAs / UAs so it might also be that for me

Cycle is the event that initiates change from IPAP to EPAP. The sensitivity settings work similarly, except detecting effort to exhale, not inhale.

Non-spontaneous cycling is when the user does not initiate exhalation in less time than Ti Max - I am not aware that Ti Min is considered for cycling.  If the user does not trigger exhalation within  Ti Max, the machine will cycle instead and that is non spontaneous.  The % Spontaneous Cycle is then the number of spontaneously initiated exhalations divided by the total number of breaths, expressed as a percentage.


I have little experience of reduced % Spontaneous Cycle because I increased Ti Max to prevent the machine cutting inhalation off too soon while I breathe deeply as I fall asleep.  It is consistently high for me.


In my therapy, I work on the basis that I want high % Spontaneous Trigger (and cycle but mainly trigger).  In fact, when I made changes to test their effect, I used reductions in % Spontaneous Trigger as negative feedback.  But is there really any problem with reduced / low % Spontaneous Trigger?  Or Cycle?

Also, do these indicators help to set T Rise, Ti Min and Ti Max?  I have basically set all of these "for comfort" since I do not have COPD - something my machine supplier told me I could do. And could or should these parameters be set to influence respiratory rate?


Now, I might be asking questions to people asking the same questions.  But if you have learned anything since this thread was started, or of anyone else can jump in and help, please reply.  Thanks.