My daddy has not given any response for 5 days after being intubated. Has anyone had a similar experience before?

My 72 year old father was intubated after he became unconscious and my mother took him to ER by an ambulance 5 days ago. He is a congestive heart failure patient and he’s had ICD for 2 years. He was feeling mostly bad for the last 6 months, however he was still able to work 2 weeks ago. Last two weeks, he has not been eating and mostly sleeping. And my mother says he had an involuntarily arm movement before he became unconscious. He raised his right hand and he kept punching his implanted ICD. My mother called our relative and an ambulance at the same time. Our relative came before the ambulance. He asked my daddy how he was and my daddy replied him by saying “I’m good, how are you?” in a very zombie mood, without moving, looking at straight. When the ambulance came, he looked very frightened with wide open eyes. He was accepted to ER and intubated right away. Since then he is not waking up, doctors are saying he is in very critical condition. After 2 days they said that his kidneys are failing too and doctors asked us if we try dialysis or if we should let him go. We continued with dialysis but doctor said no output. And then I asked him how long dialysis will continue today. This time he said there is no output but test results are not bad so they won’t make dialysis unless his results get worse. However he is not responding at all. I asked them isn’t this normal as he’s just intubated 5 days ago, They day, they don’t give him any sedative and they should have had some responses. Doctors definitely want my daddy let go. I was believing whatever they say until I read the messages here. Has anyone had any similar experience before? Is it good to try all the possible ways or are we beating up by prolonging the time? Thank you in advance. I wish everyone gets treated in a best way.