Well, I would ask her first how she is feeling. Assess, dont assume. I manage ED staff and honestly they're all okay unless there is a super super depressing case or a very difficult patient.

Otherwise, they're fine and their work day is very normal for them. There's even a few that thrive in it.

So unless her rant is about stress, maybe I wouldn't worry. Lots of people in the hospital just like talking about their day or venting. If it is about stress or something more, there's a lot of resources and interventions she can try/tap into: EAP, therapy, trying a different area in the hospital, etc.