How do I get my mom's doctors to respond in completing guardianship paperwork?

Recently, I decided to pursue guardianship over my mom. She's been in ICU on and off for three months, sometimes on a ventilator. She has recurring infections among a myriad of health issues. I did discuss it with her and she agreed to do it. It took two weeks for them to respond to my attorney's request. Now, her doctors at the hospital won't complete the physician's statement. Her PCP hasn't seen her in the last six months. What can I do?