HEAT HumiGard Evaluation Study

Laparoscopic surgery involves filling the peritoneal cavity with carbon dioxide (CO2) gas (insufflation) to increase the working and viewing space in the abdomen. It is standard care in the United Kingdom (UK) to use dry, unwarmed CO2. There is evidence that dry, unwarmed insufflation is associated with tissue desiccation and intraoperative hypothermia showing that insufflation of cool dry gas resulted in a temperature drop of 1.3-1.7°C. Despite active warming methods, perioperative hypothermia is common. One study demonstrated that nearly half of patients had continuous core temperatures of 36°C for more than an hour.

HumiGard (Fisher and Paykel Healthcare) is a CE marked medical device designed to humidify and heat CO2 for insufflation. A meta-analysis included 13 studies (total of 796 patients) comparing warmed, humidified CO2 insufflation compared to unwarmed, dry CO2 in patients having a range of procedures. There was a significant difference in mean core temperature change, and an effect size of +0.3°C (95% confidence interval [CI]: 0.1-0.6). This was more pronounced in studies of long procedures (80 min). Another meta-analysis of 15 studies (1026 patients) demonstrated a small beneficial effect on immediate post-operative pain but not at day 1 or 2. Warmed, humidified CO2 reduced the risk of intraoperative hypothermia (p=0.004) but postoperative core temperatures were not significantly different (10 studies, 718 patients). No differences were observed in analgesic consumption, length of stay, or procedure duration.

This is a blinded, randomised controlled feasibility study on 40 patients receiving laparoscopic colorectal resectional surgery at a single site (University Hospital of Wales) and treated with either the HumiGard device plus standard care (20 patients) or a sham HumiGard device plus standard care (20 patients).

This study will assess various aspects of a proposed larger pragmatic blinded, RCT evaluating whether HumiGard insufflation device, when used with standard care, can improve patients' quality of recovery after laparoscopic colectomy surgery.

The feasibility study will aim to highlight the most appropriate outcomes to be measured in a main RCT, particularly looking at the role of Quality of Recovery (QoR-40) questionnaire or continuous temperature measurements. The investigators will assess whether the outcomes of the study are suitable, achievable and measurable. The study will assess recruitment, ability to blind operating surgeon with a sham HumiGard device, use of urinary temperature probe compared to standard temperature monitoring in theatre, use of QoR-40 and visual analogue score (VAS) pain score by patients preoperatively (for a baseline score) and on post-operative day (POD) 1, 3 and 30, analgesia use, and intraoperative patient warming techniques. Length of stay in hospital from procedure to discharge (or until medically fit for discharge) will also be recorded and reported.

Furthermore, methods for analysing the postoperative complication rate will be evaluated. Complications will be recorded at POD1, POD3, upon discharge and POD30. Their severity will be graded using the Clavien-Dindo scale, a widely used and valid method for grading severity of surgical complications which helps to reduce subjectivity. The Comprehensive Complication Index (CCI) will then be used to create a composite score (0-100) for each patient.