The aim of this study is to assess if the conditioning of the insufflation carbon dioxide (CO2) allows for an additional benefit in terms of prevention of the heat loss, when compared with the usual prevention with a forced warm air blanket alone, in the setting of robot-assisted radical prostatectomy (RARP).

Among the possible consequences of cool and dry gas insufflation during laparoscopic procedures are hypothermia and cytokine response, which might cause significant perioperative morbidity. More in detail, body core temperature decrease during laparoscopic surgery has been calculated in humans as 0.3 °C for every 50 L of cold and dry insufflation gas. The reported temperature drop is caused by redistribution of heat and heat loss, both non-specific (due to anaesthesia and environmental patient exposure) and specific (due to peritoneal dry and cool insufflations). The resulting hypothermia can be severe, particularly after prolonged surgery. As for cytokine response, an increase of several pro-inflammatory cytokines has been described following the irritating effect of peritoneal CO2 insufflation.

That said, various devices of conditioning of the insufflating gas have been investigated to reduce the specific heat losses resulting from peritoneal insufflations, as well as to evaluate the inflammatory response. Previous studies conducted on animal models and clinical settings have suggested that warmed and humidified insufflation allows for an improved maintenance of body core temperature, a reduction in the degree of inflammatory response and an improved quality of postoperative course, compared with standard insufflating gas. These findings, however, are still not conclusive as they have not been confirmed by adequate randomized, controlled trials. Furthermore, no device providing warming and humidification has demonstrated a conclusive advantage over standard cold dry gas in terms of prevention of hypothermia during laparoscopy in man.

On the basis of the current available studies favouring warmed and humidified insufflation, the investigators hypothesize that a new device providing warmed and humidified insufflation (Humigard® Fisher and Paykel Healthcare®) might achieve significant benefits over standard insufflation in terms of body core temperature maintenance. The investigators also expect to document a decrease of pro-inflammatory cytokines, as a response to a diminished peritoneal irritation.

Inclusion Criteria:

• all patients undergoing RARP, with or without pelvic lymph node dissection, with a CO2 insufflation scheduled to last more than 60 minutes

Exclusion Criteria:

• patients over 80 years old, patients American Society of Anesthesiologist (ASA) status 4 or higher, patients not willing to sign the informed consent, conversions to open surgery

Adverse event data during hospital stay, an average of 4 days

Adverse events (as per Clavien-Dindo classification) directly linked to the CO2 insufflation during the robot-assisted laparoscopic procedure (standard vs Humigard)