Pressure Support

[CPAPfriend]

This is a great thread, and the beginning of it is testimony that I think every PAP user could benefit from reading: small changes in therapy can result in big changes in outcomes.

"Just wanted to add a quick update to say that your research on CA's and specifically point 2 re longer Timax may result in CA's was the issue."

Just to add comment, this makes sense, because decreasing Timax is going to decrease tidal volume, which in turn will reduce washout of CO2, which in turn will decrease CAs. All of these concepts are part of the same fabric. The respiratory rate x tidal volume = minute ventilation. You don't necessarily need to achieve a lower RR, because alternatively you can lower tidal volume, by way of decreasing inspiration time in this case.

For point 3 - Check Cycle settings, if low, potentially try increasing to med or high.
Exactly, because once again, a higher cycle will trigger exhalation sooner, cutting off inspiration and lowering tidal volume.

[zaienk]

Very interesting thread.
So If I understand well, when we want to use a higher PS to better treat random flow limitation (example UARS) and this PS induces too much CA, change the trigger and Timax parameters could be the solution to override the CA ?

[SingleH]

Thanks for further clarifcation CPAPfriend. Interesting comment about respiration rate, I have noticed how these different adjustments tend to alter respiration rate. He tends to have a slow respiration rate, but reducing PS seems to increase it.

Regarding Cycle he is on Med, but I will give High setting a try. He's dropped all the way from a spont of 80-90% to 40-60% since correcting the CA's. Im thinking to perhaps incrementally reduce PS by 0.2 and like wise Timax by 0.1 step by step to see where I can find the best balance of CA's vs Spont cycle figure.

[SingleH]

Hi Zaienk,

Yes it does seem to be a solution that can be applied if you are experiencing CA's.

You could possibly also consider increasing Cycle from Low to Med, or med to High also, but probably best to adjust trigger and Timax first.