Im so sorry to hear about this recent development
@margherita
In UK, care home and nursing homes, do not use drips. If someone needs IV fluid or other treatment it is done in hospital. I think it would be a good idea to try and have a very open and frank talk with the doctor who is overseeing this. Try and find out the reason why - is it due to heat, for example? - and what they expect the outcome to be. Is this due to something that they expect him to recover from? Has he, in fact, lost his swallow?
I think my biggest concern would be that the recent spell in hospital has propelled him towards End of Life. It may not be the case here, but I am thinking of mum who ended up in hospital after a broken hip and after being returned to her care home just stopped eating and drinking. She was sent back to the hospital, who used a drip to rehydrate her and returned her to the care home, but she was still not eating or drinking. I had a long talk with her doctor who said that he thought she had reached End of Life and agreed that it would be best not to keep rehydrating her and just let nature take its course. This may not be what is happening to Nick, but I do think you need to talk to the doctor to find out what is happening.