I just did this last weekend - 97 yr gpa had a heart attack. Called UA and NW both would get me out within 3 hrs on a Medical Emergency fare I had to provide the Hospital name, phone and DR name. Rate was better than I could find on the internet and both would allow an open ended ticket.
Took NW as time would get me in 1.5 hrs faster booked return for 1 week later - Gpa is a trooper and came through great and I came home Thursday.

Good Luck