1. Trauma Service, The Royal Children’s Hospital Melbourne, Parkville, Victoria, Australia;
2. Department of Epidemiology & Preventive Medicine, Monash University, Melbourne, Victoria, Australia;
3. Prehospital, Resuscitation and Emergency Care Research Unit, School of Nursing, Midwifery and Paramedicine, Curtin University, Bentley, Western Australia, Australia;
4. Division of Emergency Medicine, The University of Western Australia, Crawley, Western Australia, Australia