Sedation of terminally ill patient

My mother is an 89 year old woman who made Aliyah 2 years ago.
She underwent a TAVI at Shaarei Tzedek in March 2016.
She recovered in CCU and after day5/6 stood up with assistance.
She was on a NG tube and ventilator
That night she was given 3 large Slow K tablets by mouth.She protested that she was choking-her protests were ignored and the next day she was transferred to regular cardiac ward-she experienced difficulty breathing-was transferred the same day back to CCU-on investigation she had developed ARDS.
She never recovered and has never manged to get off the ventilator again or NG tube or the bed.
She requested to me ,her son ,that I ensure that she sleep through this as she could not take the suffering- I beleive it may be due to a drowning sensation.
With help from a private ICU doctor she was given Dormicum and Fentanyl.
Shw was transferred to geriatrics and they refused to give her Dormicum but gave Clonex and Fentanyl – which seemed to work but she experienced periods of wakefulness.
She was transferred to Hertzog for about a week but back to Shaarei Tzedek with pneumonia.
She currently (Sep 2016) remains on a ventilator ,NG tube,immobile, and wakes up infrequently. She is malnourished and weighs 35kg and is in CCF ,ARDS, aspirates frequently,of dubious neurological status.
She is permantly swollen from inability to find veins and I am not sure if Clonex ever gets into the veins.
The question:
Is it mutar to sedate her with Dormicum using a permanent peripheral line (she does not have one currently)?
Can I compel Shaarei Tzedek to do so if mutar?
Can I threaten Shaarei Tzedek with a din Torah if they fail to comply with my wishes – I am her only son and am her medical Power of Attorney.
This is urgent as she may be suffering as we speak