Ok, update:
As of Fri morning we are doing basically nothing <img src="i/expressions/face-icon-small-sad.gif" border="0">
We ended up at our local childrens and are in the ICU. Trying to get transferred about 2hrs away to where his liver Dr is based, but there is not an open PICU bed so they are trying to pull strings.
Pulmo-wise: on 9L O2 he is stating around 95-96%; if you pull the mask he drops to 90-91%
Liver-wise: ammonia is still high (waiting for new labs this AM) and acting altered, but can't do anything until we get him transferred to where the liver team is.
Thank you all for your thoughts,