作者单位:Department of Surgery, Skaraborg hospital, K?rnsjukhuset, Sk?vde, Sweden[1]Senior Lecturer, The Institute of Health and Care Sciences, The Sahlgrenska Academy at G?teborg[2]Department of Anaesthesia, Skaraborg hospital, K?rnsjukhuset, Sk?vde, Sweden[3]Department of Surgery, Skaraborg Hospital, K?rnsjukhuset, Sk?vde, Sweden[4]