[1] Royal Childrens Hosp, Dept Paediat Anaesthesia & Pain Management, Melbourne, Vic, Australia
[2] Murdoch Childrens Res Inst, Anaesthesia Res Unit, Melbourne, Vic, Australia
[3] Univ Melbourne, Dept Paediat, Melbourne, Vic, Australia
[4] Royal Childrens Hosp, Oral & Maxillofacial Surg Unit, Melbourne, Vic, Australia