That's fairly common practice, the issue was moreso the people left in the room were not the usual qualified people to do so and also the amount of time spent outside of the OR resulting in longer anaesthesia thus higher risk to patients etc. UPMC patients sign an agreement which contains acknowledgment that the surgeon may/will perform other surgeries during theirs. The legality surrounding this agreement and the specific length of time etc was a main point of contention in this case and one of the factors that kept this case from going class action