Occ health is about as different from PICU as I could imagine... so you might think about how you'd care for ambulatory working adults in a typically solo-RN, non-hospital setting.
Of course, have a good answer why you want such a major change.
Read this specialty thread, esp. the introductions/rollcall, for an idea about what we do and challenges we face in this role. For a panel interview, you'll probably have questions like "How did you handle..." and "How have you demonstrated success in..."
Good luck!