1. Department of Anaesthesiology; Nordsjaellands Hospital; Hillerød Denmark
2. Copenhagen Trial Unit; Rigshospitalet; Copenhagen Denmark
3. Juliane Marie Centre; Rigshospitalet; Copenhagen Denmark
4. Department of Anaesthesiology and Intensive Care; Aarhus University Hospital; Aarhus Denmark
5. Department of Cardiology; Holbaek Hospital; Holbaek Denmark
6. Department of Anaesthesiology; Herlev Hospital; Herlev Denmark