[1] Westmead Hosp, Dept Anaesthesia, Westmead, NSW, Australia
[2] Royal Prince Alfred Hosp, Sydney, NSW, Australia
[3] Greater Sydney Helicopter Emergency Serv, Sydney, NSW, Australia
[4] Westmead Hosp, Dept Anaesthesia & Perioperat Med, Westmead, NSW, Australia
[5] Univ New South Wales, George Inst Global Hlth, Westmead, NSW, Australia
[6] Western Sydney Univ, Sydney, NSW, Australia
[7] Monash Univ, Australian & New Zealand Intens Care Res Ctr, Melbourne, Vic, Australia
[8] Alfred Hosp, Melbourne, Vic, Australia
[9] Royal Prince Alfred Hosp, Fac Med, Dept Cardiol, Sydney, NSW, Australia
[10] Univ Sydney, Sydney, NSW, Australia
[11] Westmead Hosp, Dept Anaesthesia, Hawksbury Rd, Westmead 2145, Australia