You risk assess the situation before you go in the room. You make sure every room has panic alarms, or that individuals have panic alarms. You make sure that the patient is never between you and the door. (All of this is standard practice).

You have two (or more) members of staff dealing with that person.

You de-escalate at every opportunity.

You have stuff like rapid tranquilisation and restraint available (although these are methods of last resort).