Perioperative Endothelial Dysfunction in Patients Undergoing Major Acute Abdominal Surgery

Inclusion criteria * ≥ 18 years old * Surgery within 72 hours of an acute admission to the Department of Surgery or an acute reoperation. * Major gastrointestinal surgery on the gastrointestinal tract. This will include * Open, laparoscopic, or laparoscopically-assisted procedures * Procedures involving the stomach, small or large bowel, or rectum for conditions such as perforation, ischaemia, abdominal abscess, bleeding or obstruction * Washout/evacuation of intra-peritoneal abscess (unless due to appendicitis or cholecystitis - excluded, see below) * Washout/evacuation of intra-peritoneal hematoma * Bowel resection/repair due to incarcerated umbilical, inguinal and femoral hernias (but not hernia repair without bowel resection/repair) * Bowel resection/repair due to obstructing/incarcerated incisional hernias provided the presentation and findings were acute * Laparotomy/laparoscopy with inoperable pathology (e.g. peritoneal/hepatic metastases) * Laparoscopic/Open Adhesiolysis * Return to theatre for repair of fascial dehiscence * Any reoperation/return to theatre meeting the criteria above is included If multiple procedures (primary surgery or reoperation) are performed on different anatomical sites within the abdominal/pelvic cavity, the patient would be included if the major procedure is general surgical. Exclusion criteria * Not capable of giving informed consent after oral and written information * Previously included in the trial * If transferred directly from the operation room or recovery ward to the intensive care unit * Elective laparoscopy * Diagnostic laparotomy/laparoscopy where no subsequent procedure is performed (NB, if no procedure is performed because of inoperable pathology, then include) * Appendectomy +/- drainage of localized collection unless the procedure is incidental to a non-elective procedure on the GI tract * Cholecystectomy +/- drainage of localized collection unless the procedure is incidental to a non-elective procedure on the GI tract (All surgery involving the appendix or gallbladder, including any surgery relating to complications such as abscess or bile leak is excluded) * Non-elective hernia repair without bowel resection. * Minor abdominal wound dehiscence unless this causes bowel complications requiring resection * Ruptured ectopic pregnancy, or pelvic abscesses due to pelvic inflammatory disease * Laparotomy/laparoscopy for pathology caused by blunt or penetrating trauma * Laparotomy/laparoscopy for esophageal pathology Laparotomy/laparoscopy for pathology of the spleen, renal tract, kidneys, liver, gall bladder and biliary tree, pancreas or urinary tract