Can I admit my sister to the hospital for a medical/mental evaluation if I have power of attorney

My older sister is 74 years old and is suffering from dementia. She has brief moments in which she is lucid, but otherwise she has all of the signs and symptoms of dementia. She resides in another city and I recently brought her to my home because of concerns about her health and safety. She has lived alone for most of her adult life and over the past 2 years her health has significantly declined. I had been travelling to her home once a month to ensure she has food and is eating. She has health problems and I know she is not taking her medication nor does she leave the home to purchase groceries or attend doctor appointments. She hides everything and then calls me daily complaining that someone is coming into her apartment and taking things. She has refused care. Can I admit her anyway.