Effects of intraoperative insufflation with warmed, humidified CO₂ during abdominal surgery: a review

Purpose: During a laparotomy, the peritoneum is exposed to the cold, dry ambient air of the operating room (20°C, 0%–5% relative humidity). The aim of this review is to determine whether the use of humidified and/or warmed CO₂ in the intraperitoneal environment during open or laparoscopic operations influences postoperative outcomes. Methods: A review was performed in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The PubMed, OVID MEDLINE, Cochrane Central Register of Controlled Trials and Embase databases were searched for articles published between 1980 and 2016 (October). Comparative studies on humans or nonhuman animals that involved randomized controlled trials (RCTs) or prospective cohort studies were included. Both laparotomy and laparoscopic studies were included. The primary outcomes identified were peritoneal inflammation, core body temperature, and postoperative pain. Results: The literature search identified 37 articles for analysis, including 30 RCTs, 7 prospective cohort studies, 23 human studies, and 14 animal studies. Four studies found that compared with warmed/humidified CO₂, cold, dry CO₂ resulted in significant peritoneal injury, with greater lymphocytic infiltration, higher proinflammatory cytokine levels and peritoneal adhesion formation. Seven of 15 human RCTs reported a significantly higher core body temperature in the warmed, humidified CO₂ group than in the cold, dry CO₂ group. Seven human RCTs found lower postoperative pain with the use of humidified, warmed CO₂. Conclusion: While evidence supporting the benefits of using humidified and warmed CO₂ can be found in the literature, a large human RCT is required to validate these findings.