A Melbourne surgeon allegedly killed in a one-punch attack fell to the ground so hard the back of his head cracked the tiled floor of the Box Hill Hospital in Melbourne's east, a court has heard.

Joseph Esmaili, 22, is facing numerous charges including manslaughter for allegedly delivering the punch that killed 41-year-old Patrick Pritzwald-Stegmann in May last year.

His committal hearing at the Melbourne Magistrates' Court was told the pair had been having an argument over Mr Esmaili and his friends smoking in a designated non-smoking area outside the hospital's foyer.

Prosecutor Mark Gibson SC said Mr Pritzwald-Stegmann had gone to reception to ask them to call security to move the group away from the hospital entrance when Mr Esmaili came back inside.

"[Mr Pritzwald-Stegmann] requested the accused man to leave the hospital … [he] was heard by witnesses to say to the accused 'did you just spit in my face?'" he told the court.

Mr Gibson said witnesses told police they had heard Mr Esmaili say "I need you to suck my dick" as he became "more annoyed and angry".

Mr Pritzwald-Stegmann put down the satchel he was carrying before Mr Esmaili punched him in the face, the court heard.

Mr Gibson said the punch rendered the surgeon unconscious and caused him to fall backwards without attempting to brace the fall.

"The evidence suggests that the back of his head cracked the tiled floor," he said.

The court heard Mr Esmaili fled from the scene as onlookers and medical staff rushed to Mr Pritzwald-Stegmann's aid.

Mr Esmaili chose not to watch CCTV of the incident which was played in court.

Defence barrister John Desmond told the hearing that his client may claim he was acting in self defence.

Mr Desmond also indicated he would argue the surgeon's death was not caused by Mr Esmaili's punch.

Surgeon 'too agitated' to talk, not following commands

Anaesthetist Dr Gordon Mar told the court he was one of the first doctors to attend to Mr Pritzwald-Stegmann as he lay on the floor outside the lifts.

"It appeared that he was not aware of his surroundings … he was trying to get up, he was moving his hands around, he wasn't lying still for us," he said.

"We tried to talk to him but he was too agitated, we couldn't get him to follow any commands."

Dr Mar told the hearing that the surgeon was also vomiting, all symptoms consistent with a serious head injury.

Mr Desmond asked if he had seen Mr Pritzwald-Stegmann's head come into contact with anything as he writhed around or if he had fallen from the gurney as he was transported to the emergency department and to have a CT scan.

Dr Mar responded that he did not see him injure himself.

More than 20 witnesses are expected to give evidence at the hearing before Magistrate Ross Maxted.