It's likely that the hospital is warm and dry, and that combines to dry the mucous membranes quickly. My lips, after only about 8 hours were dry and cracking, and I got irritated sinuses from the warm, dry air. Might they let you bring in a humidifier when you visit? They probably wouldn't let you leave it, but at least you could make the air a little softer while you're there.
No rules will not allow anything electrical because they have to be safety checked etc before they are allowed it is the same at my place of work.
The oxygen he is getting is going through a humidifier though as this is hospital policy because he is permantly connected.
Even so it still dries him out and he is often requesting drink which I have to ration as they do not want too much fluid going into him.