Effect of warm humidified insufflated carbon dioxide on wound bacterial load in open elective gastrointestinal surgery: a pilot investigation.

Surgical site infection (SSI) is an infection which can develop in the wound created by a surgical procedure. SSI is a potential side effect of any surgical procedure. The purpose of this investigation is to provide data for helping design a larger controlled study which will investigate whether blowing warm, humidified carbon dioxide (CO2) into the surgical cavity during surgery can reduce the number of bacteria in the surgical wound, potentially reducing the risk of SSI. We are also interested in how the gas treatment alters the way your skin wound edge responds and heals. It is possible that the gas may improve the healing process after surgery. Participants undergoing elective gastrointestinal surgery at Auckland City Hospital who meet the inclusion and exclusion criteria will be offered the opportunity to participate in the pilot study. If patients meet the above criteria and choose to take part in the study, they will be randomised (selected by chance by a computer) to receive the CO2 treatment or standard care (no CO2). If randomised into the CO2 treatment group, warm humidified CO2 gas will be slowly insufflated (blown) into the abdominal cavity during the planned surgery. The CO2 gas is delivered by a small, flexible, non-invasive tube which is placed inside the surgical wound during the operation. This trial will take 30 days to complete, not including an initial assessment to check if the patient meets the inclusion and exclusion criteria. There will be 4 scheduled assessments. These assessments will be undertaken during the standard routine check-up expected after surgery so will not take any additional time. Assessments will be made at the following time points. Day 1 (surgery), Day 5 (in-patient), Discharge, Day 30 Follow-Up Visit. To measure the number of bacteria in the wound, a swab will be taken by gently wiping the edge of the wound of all participants. Samples will be taken by the surgeon while the patient is under an anesthesia at the beginning of the surgery; 1 hour into the procedure; 2 hours into the procedure; and at the end of the surgery before the surgical wound is closed. In addition two sets of two small biopsies (small samples of your skin wound) during the operation will be taken. These biopsies are taken while the patient is under anesthesia from along the skin edges that are already part of the main operation wound. They will be inside the area of the main operation wound and will not make the scar any longer. On Day 5, the surgical dressing will be removed at 48hrs post-surgery, and the wound will be reviewed by a nurse to check for any potential SSI. At discharge the surgical wound will be reviewed by a nurse to check for any potential SSI. The patient will be contacted again at 30 days to discuss any SSI have developed.