I was going to say "depends on what you mean" but by explaining it was "a hot patient"--it is entirely inappropriate to flirt. If what you mean is to joke around and be friendly depends on the situation and the patient. If I have a patient who knows each time they see me, it is hardly anything nice, I do try and lighten the mood a bit "Yes, it is me Nurse Jade again. Like a bad penny I just keep turning up". Sometimes, it will lighten a situation. But again, depends.
If you are a bowel care consultant, it may make a patient feel more comfortable talking about something that most patients find really embarrassing if you do lighten the mood a tad. "I am Nurse Bowel Consultant and contrary to what you may be thinking I am not bowel obssessed...." or something along those lines.