Any advice for my Mom's quality of life depends on it?

My mother was admitted to the hospital 7 days ago the doctors told me whenI arrived at the hospital that my was admitted for lung failure she could not breathe on her own. after my mother was sent up to the ICU my mother's status is completely unconscious depending on a ventilator the next day the doctor told me that my mother had sepsis and that she would most likely not survive.so me and my sister sitting by my mother's bedside start to see some type of life in my mother I'm movement she seems to be agitated trying to sit up only to lay back down seeming to fall into a deep sleepI have also been able to communicate with my mother and she replies back with head nods and from time to time if we ask her to squeeze our hand she will I asked her if she's in pain she says no . and my mother doing these things make me and my sister very hopeful but then she always seems to fall right back into a deep sleep the doctors once they got my mother stable as far as blood pressure and heart rate they tried to wake her up she was taking off all sedatives and the doctor said she should wake up usually around 40 minutes after all sedatives have worn off .yesterday my mother seemed to be doing a lot better as far as showing signs of life she's sitting up and then slowly laying back down moving your feet around and sliding around on the bed the doctors don't want her to pull her tube out so they gave her ativan and then fentanyl for my moms agitation and so she could relax now this is where I become confused they tell me that my mother has delirium and that's why she is not waking up something about it's taking a long time for the drugs to wear off and this is where I ask why are they continuing to dope her I have asked the doctors and nurses this question but they seem to be more worried about her pulling her ventilator tube out but if you Dopeing her all the time she'll never wake up we also asked the doctor for a brain scan to see if it would show anything and I couldn't believe he said it wouldn't show anything me and my sister strongly disagreed on the spot whether it would be for her health or quality of life I see signs of life but I need to know if there's other people that have gone through the roller coaster ride that me and my sister are on I'm sorry everybody I know that some of this may not make much sense but if you have gone through this I know you understand what do we do