1. Department of Anaesthesiology and Intensive Care, Bispebjerg Hospital, Bispebjerg Bakke 23, 2400 København NV, Denmark
2. Department of Anaesthesiology and Intensive Care, Hvidovre Hospital, Kettegård Alle 30, 2650 Hvidovre, Denmark
3. Department of Anaesthesiology and Intensive Care, Nordsjællands Hospital, Dyrehavevej 29, 3400 Hillerød, Denmark