The Effect of Surgical Humidification in Colorectal Cancer Surgery: a Randomised Controlled Trial

Delivery of warmed, humidified CO2 to the peritoneal cavity during laparoscopic and open abdominal colorectal cancer surgery. Participants in the study group will receive warmed (37 degrees Celsius), humidified (98%) CO2 via insufflation in the minimally invasive group or wound insufflation in the open group. The HumiGardTM humidification system (MR860; Fisher and Paykel Health Care, Auckland, New Zealand) has been independently tested to confirm the effectiveness of gas humidification. Anticipated duration of surgery for any group is between 2 to 4 hours. For both laparoscopic surgery groups, pneumoperitoneum will be established after insertion of a 12mm port by open method. Further 10mm and 5mm ports will be inserted according to the type of laparoscopic procedure. The laparoscopic control group will receive non humidified unwarmed CO2 delivered by a standard insufflator. For the study laparoscopic group the insufflation tubing will include the humidification system consists of a bacterial filter and a humidification chamber filled with 180 mL sterile water, attached to a humidifier controller that includes an integrated temperature and flow sensor. The outlet of the humidification chamber is connected to a thermally insulated 2.5m long heated insufflation tube that maintains temperature and humidity of the gas to its outlet. In the open group dry CO2 is delivered via a 6.35mm polyvinylchloride tube to the open surgery humidification system (F&P HumiGard, Fisher & Paykel Healthcare Ltd, Auckland, New Zealand). This is attached to flexible tubing and positioned inside the open abdominal wound cavity in the right upper quadrant, a depth of approximately 4 cm from the skin. Insufflation of warmed, humidified CO2 will be continued from the time the laparotomy incision is made until just before abdominal wall closure. The control open group will not receive any insufflation. Adherence to protocol, the pressure, flow rate and total volume of CO2 delivered will be recorded by an observer in the operating room for both groups.