[1] Royal Brisbane Hosp, Intens Care Facil, Herston Rd, Brisbane, Qld 4029, Australia
[2] Univ Queensland, Royal Brisbane Hosp, Div Anaesthesiol & Intens Care, Brisbane, Qld 4029, Australia
[3] Chinese Univ Hong Kong, Prince Wales Hosp, Dept Anaesthesia & Intens Care, Hong Kong, Peoples R China
[4] Christchurch Hosp, Dept Anaesthesia, Christchurch, New Zealand