Warm and humidified insufflation gas during gynecologic laparoscopic surgery reduces postoperative pain in predisposed patients-a randomized, controlled multi-arm trial

Background: Postoperative pain remains a common problem in gynecologic laparoscopy, especially in head zone-related regions, triggered by intra-abdominal pressure during capnoperitoneum. Humidified and prewarmed insufflation gas may ameliorate pain and be beneficial.

Methods: This prospective randomized controlled parallel group multi-arm single-center study investigated the effects of temperature and humidity of insufflation gas on postoperative pain during gynecologic laparoscopy with a duration ≥ 60 min. Female participants (18-70 years) were blinded and randomly assigned-computer generated-to either insufflation with dry cold CO₂ with forced air warming blanket ("AIR"), humidified warm gas without forced air warming blanket ("HUMI"), or humidified warm gas with forced air warming blanket ("HUMI +"). We hypothesized that using humidified warm gas resulted in lower pain scores and less analgesic consumption. The primary endpoint postoperative pain was assessed for different pain localizations every 12 h during 7 days after surgery. Secondary endpoints were demand for painkillers and epidural anesthetics, length of stay in recovery room, and hospital stay. (Registration: ClinicalTrials.gov NCT02781194-completed).

Results: 150 participants were randomized. Compared to group "AIR" (n = 48), there was significantly less pain in group "HUMI +" (n = 48) in the recovery room (- 1.068; 95% CI - 2.08 to - 0.061), as well as significantly less ibuprofen use at day two (- 0.5871 g ± 0.258; p-value = 0.0471). Other variables did not change significantly. Stratification for presence of endometriosis or non-previous abdominal surgery in patient history revealed significantly less pain in both groups "HUMI" (n = 50) and "HUMI +" versus group "AIR." Related side effects were not noted.

Conclusion: In the overall population, the use of warm, humidified insufflation gas did not yield clinically relevant effects; however, in predisposed patients with endometriosis and who could otherwise expect high pain levels, warm and humidified gas may be beneficial.