@Andrew_Eroh
Sorry to hear such thing. Its hard to say anything without background. But one thing I’m pretty sure about it are infusions of magnesium (slow, very slow running!). Its a strong Calcium-channel blocker and is needed for anything. It counteracts activation of neurons, e.g. to EMFs.
There are other things but in an ICU setting, with all the unknowns, IV Magnesium may be a good thing that a) is practical b) is known to the doctors and c) has a superior safety profile. Vitamin C I would do, too. But I have heard of settings where doctors did not want to do this, because they never did it, its not in their protocols and they would be liable. So better a dead patient, then liability. You may have to check that aspect, too and free them of liability.
I would not holding back with Mg, but maybe also supply basic electrolytes like K and Na under monitoring if required.
It would be helpful to know of what has triggered the autoimmunity issue in a child.
Disclaimer: This is not advice, this is what I would like to happen to me in such a situation. I also got Mg and Vit C IVs may times - but they have to be slow running!
Here are some things to watch out for in case you want to do more then Mg