1. Department of Neurosurgery, Sir Charles Gairdner Hospital and Royal Perth Hospital, Perth, Western Australia, Australia.
2. Department of Intensive Care Medicine and School of Population Health, University of Western Australia, Perth, Western Australia, Australia.
3. Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Perth, Western Australia, Australia.
4. Department of Anaesthesia, Royal Perth Hospital, University of Western Australia, Perth, Western Australia, Australia.
5. Dunedin Hospital and Otago Bioethics Centre, University of Otago, Dunedin, New Zealand.