The aim of the clinical study is:

1. to examine the association between postoperative endothelial function, indirectly measured by reactive hyperemia index, and major adverse cardiovascular events including myocardial injury and cardiac death within 30, 90 and 365 days of acute abdominal surgery.
2. to examine the association between postoperative endothelial function, indirectly measured by reactive hyperemia index, and non-cardiovascular complications including non-cardiac death within 30, 90 and 365 days of acute abdominal surgery.
3. to examine the importance of the postoperative blood glucose level and the pulmonary function for postoperative complications and death within 30, 90 and 365 days of acute abdominal surgery.
4. to examine the association between postoperative endothelial function, pulmonary function and blood glucose level
5. the qualitative part of the study will examine the postoperative subjective symptoms including acute and chronic pain, quality of recovery and functional status, depressive thoughts and post-traumatic stress disorder.

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

Patients undergoing major acute gastrointestinal surgery

We do not plan to share IPD