Spontaneous Trigger %

I am using the ResMed AirCurve 10 VAuto in bi-level spontaneous mode.

Upon reviewing the data the spontaneous trigger % value is usually between 50 - 80%. I haven't seen it reach 100%.

I have a restrictive lung disease so I have the trigger setting at the highest (to trigger a breathe during even minimal inhalation efforts) and the cycle setting at the lowest (to help extend the inhalation phase - i assume to give me more time to trigger a breath).

Does this mean that the machine is not sensing a breathe for the missing percentage? Or is the missing percentage the times the machine sensed a weak breath and then kicked in to deliver the prescribed pressure? I don't have the S/T machine, so I do not have a backup rate.

I am worried that for a good portion of the night the machine is not detecting my breaths...but in looking at the data I do not suffer from central apneas (unless I crank up the pressures).


My thoughts are:

Experiment with extending Ti Min and Ti Max to allow more time to hopefully make an effort to have a spontaneous breath...I'm not sure it works that way though

ResMed literature states the following which seems to support my theory:

"Ti Min prevents the premature cycling to EPAP for patients whose inspiratory pressure is extremely weak"

raisedfist wrote:I am using the ResMed AirCurve 10 VAuto in bi-level spontaneous mode.

Upon reviewing the data the spontaneous trigger % value is usually between 50 - 80%. I haven't seen it reach 100%.

where are you seeing this data? it's very strange, since the vauto is a 100% spontaneous machine, it has no timed feature.

raisedfist wrote:and the cycle setting at the lowest (to help extend the inhalation phase - i assume to give me more time to trigger a breath).

no, cycle doesn't happen until after you've triggered ipap. it works like this:

rest> start of inhalation> trigger and switch to IPAP> wait at least TiMin> either inhalation stops, or TiMax expires> cycle and switch to EPAP> rest.

cycle sensitivity is how sensitive the machine is to your ending your inhalation phase, and is only effective between TiMin and TiMax time after the machine triggers to IPAP.

raisedfist wrote:Does this mean that the machine is not sensing a breathe for the missing percentage? Or is the missing percentage the times the machine sensed a weak breath and then kicked in to deliver the prescribed pressure? I don't have the S/T machine, so I do not have a backup rate.

I am worried that for a good portion of the night the machine is not detecting my breaths...but in looking at the data I do not suffer from central apneas (unless I crank up the pressures).

I don't know, that number doesn't seem to be appropriate for a vauto.

raisedfist wrote:Experiment with extending Ti Min and Ti Max to allow more time to hopefully make an effort to have a spontaneous breath...I'm not sure it works that way though

no, it doesn't.

raisedfist wrote:ResMed literature states the following which seems to support my theory:

"Ti Min prevents the premature cycling to EPAP for patients whose inspiratory pressure is extremely weak"

no, it doesn't, you can't cycle until you've already triggered to IPAP. what I believe it means is that if you have a weak inhalation, then you can reduce cycle sensitivity so that the machine doesn't prematurely think you've stopped trying to inhale.

If I unlock the clinical menu on the machine, when I view the sleep report on the LCD screen for a night of sleep data, according to the clinical menu there can be two values reported, depending on the mode of therapy:

Spont Trig: Percentage of breaths that are spontaneously triggered, measured from the last 20
breaths.

Spont Cyc: Percentage of breaths that are spontaneously cycled, measured from the last 20
breaths


I will have to take a closer look when I get home. Maybe I am confusing the two and worrying myself needlessly. And maybe it only reports the Spont Cyc value anyway, since 100% of my breaths should be spontaneous with the machine I have.

raisedfist wrote:I will have to take a closer look when I get home. Maybe I am confusing the two and worrying myself needlessly. And maybe it only reports the Spont Cyc value anyway, since 100% of my breaths should be spontaneous with the machine I have.

could be, like you say, your machine, if it's a vauto, doesn't have the ability to timed trigger.