In order to confirm the animal data in the human, a first RCT was performed in which 20 women undergoing a laparoscopy for at least 60 minutes were randomised to a pneumoperitoneum with either 100% carbon dioxide or 96% carbon dioxide plus 4% of oxygen. Insufflation pressure and Trendelenburg were standardised at 15 mm Hg and 30° respectively. In a second trial women were randomized to either 100% carbon dioxide or 86% carbon dioxide plus 4% of oxygen + 10% nitrous oxide + humidification and set temperature of 32°C of the peritoneal cavity.