M L Fabritius1, J Wetterslev2, J B Dahl1, O Mathiesen3. 1. Department of Anaesthesiology and Intensive Care Copenhagen University Hospital, Bispebjerg and Frederiksberg Hospitals, Copenhagen, Denmark. 2. Copenhagen Trial Unit, Centre for Clinical Intervention Research, Copenhagen University Hospital, Copenhagen, Denmark. 3. Department of Anaesthesiology, Zealand University Hospital, Køge, Denmark.