1. * Research Fellow, Herlev Hospital.† Junior Staff Anesthetist, Esbjerg Central Hospital.‡ Junior Staff Anesthetist, Herlev Hospital.§ Staff Anesthetist, Odense Hospital.‖ Junior Staff Anesthetist, Glostrup Hospital.# Junior Staff Anesthetist, Hillerød Central Hospital.¶ Staff Anesthetist, Glostrup Hospital.** Associate Professor and Director Anesthesia Technology, Massachusetts General Hospital.†