1 Department of Intensive Care Medicine, Royal Perth Hospital, Wellington St, Perth, Western 6000, Australia. Electronic address: he125188@health.wa.gov.au.
2 Department of Intensive Care Medicine, Royal Perth Hospital, Wellington St, Perth, Western 6000, Australia.
3 Department of Neurosurgery, Royal Perth Hospital, Wellington St, Perth, Western Australia 6000, Australia; Department of Neurosurgery, Sir Charles Gairdner Hospital, Nedlands, Western 6009, Australia.