The object of adjusting the BiPAP settings would be to minimize the morphine while providing the right amount of support for breathing. Instead of morphine for air hunger, most people, until the very end, only need a settings adjustment. Through managing the number of breaths and how they are triggered/structured, as well as the volume of each breath, we can provide just the right amount of air to make the PALS comfortable so they are not feeling the air hunger that the morphine is supposed to address. It's when there's air hunger but nowhere else to go on settings that morphine is advised.
Well-intentioned clinicians who know more about morphine than BiPAP will argue that using morphine earlier keeps breathing shallow and therefore more comfortable by reducing the work of breathing, when the BiPAP is well equipped to do that more directly and reproducibly [there are more settings for BiPAP than morphine, and real-time adjustment] when set properly and does not cause sedation/fatigue.
It is true that CO2 buildup can manifest as fatigue, confusion, headaches, lack of appetite, and irritability, and that buildup is often down to settings not being reduced when muscles/lungs/other organs can no longer handle the same volume of air, or need the same volume at a different interval/rhythm. And what causes CO2 buildup? Not being able to exhale the air that has that CO2 in it. But most PALS are getting too much air in late disease, not too little, and morphine makes it harder to exhale it.
Again, at the end, this balance no longer holds and so we typically play it out with morphine because CNS effects and CO2 levels are not the issue any more.
I'll PM you about her settings.