From the 4/7/2016 Washington Post: "Patient secretly recorded doctors as they operated on her. Should she be so distressed by what she heard?"
Although I don't do surgery, I do sometimes perform invasive procedures on unconscious or sedated patients. I always speak as if the patient were fully awake and able to understand me.
One can debate the ethics of recording one's doctor when they aren't aware of it. I do fully support recording important doctor visits with the consent of both parties, as I discussed last year in, "Why You Should Record Your Doctor Visits".