AirCurve Trigger high works well for me but why?

[yrnkrn]

Altough I don't have any respiratory diseases, my flow waveforms are better, less "noisy" and more consistent with Trigger High than Trigger Medium (the default).
With Trigger Medium AirCurve misses single breath



or two in a row, marking "formal" apnea



Why should this happen?

[Sleeprider]

If you occasionally have a weak spontaneous effort to start inspiration, the high or very high sensitivity will convert to IPAP. It still follows respiration, but will trigger IPAP with a lower pressure change. Without CPAP, our airway is actually under negative pressure during inspiration, and the increase in negative pressure is why many people experience obstructive apnea. Expiration is always a passive effort and results in positive airway pressure. Right at the transition, the airway approached zero flow. With CPAP the airway is under positive pressure all the time, but flow is still near zero at transition, and the start of inspiration can be hard to detect. You can see a number of tiny flow changes occur at the end of your exhale. With high sensitivity, the machine is more likely to trigger on these variations than waiting for the strong flow increase associated with inspiration. With high or very high trigger sensitivity, the weak breaths in your first chart at 02:39:48 and 02:40:48 would trigger, but with medium trigger, the pressure does not switch to IPAP.

One way to look at it is, high trigger sensitivity is like putting the machine is sports-car mode, and medium is like touring or cruise. It's not for everyone, but it can get things moving with a lighter touch on the throttle.

[yrnkrn]

Thanks for the thorough explaination!
I suffer from persistent flow limitations not solved by CPAP pressure but are solved by pressure support=4 to 5.
Can we differentiate weak spontaneous effort ("central") from the physical flow limitation ("obstructive") using the CPAP flow only?
If central, maybe the weak effort is due to the pressure support?

[Sleeprider]

Flow limitation is a decreasing flow as inspiration progresses, resulting in a graph with flat or downward sloping inspiratory peak. FL is usually restrictive or obstructive in nature. A weak respiratory transition is just a lack of spontaneous effort, rather than restriction. It could be related to central hypopnea or apnea, but I wasn't going to go that far.