Department of Intensive Care Medicine and Department of Emergency, Anaesthesia and Pain Medicine, Tampere University Hospital, Tampere, Finland. PO Box 2000, FI-33521 Tampere, Finland; Intensive Care Unit, Liverpool Hospital, Sydney, Australia. Cnr Elizabeth and Goulburn Sts, Liverpool, NSW 2170, Australia. Electronic address: joonas.tirkkonen@tuni.fi.