Dept of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden; Dept of Anesthesia and Intensive Care, Karolinska University Hospital Huddinge, Stockholm, Sweden. Electronic address: Christina.Blixt@sll.se. Dept of Anesthesia and Intensive Care, Karolinska University Hospital Huddinge, Stockholm, Sweden. Electronic address: mirjam.m.larsson@sll.se. Dept of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden. School of Medical Sciences, Dept of Surgery, Örebro University & Department of Surgery, Örebro University Hospital, SE-701 85, Örebro, Sweden. Electronic address: olle.ljungqvist@oru.se. Dept of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden. Electronic address: olav.rooyackers@ki.se.