My mom has gangrene of toes and necrotic tissue on the foot, she is diabetic with heart failure and kidney failure, she is living with me and her care is now end of life, she is almost completely bed bound as she can not put weight on affected foot, she takes oxicodon slow release 25mg x2 daily and oxinorm liquid 5/10 mils as per rqst, how long can this go on and what should I expect