[1] Univ Auckland, Sch Med, Dept Anaesthesiol, Auckland, New Zealand
[2] Auckland City Hosp, Green Lane Dept Anaesthesia, Auckland, New Zealand
[3] Blacktown Hosp, Dept Intens Care, Sydney, NSW, Australia
[4] Univ Western Australia, Dept Pharmacol, Perth, WA 6009, Australia
[5] Royal Perth Hosp, Perth, WA, Australia
[6] Auckland Univ Technol, Fac Hlth, Auckland, New Zealand