Core temperature monitoring is mandatory during major surgery. The accurate techniques currently used are invasive, such as artery catheter and oesophagal probe. A new non-invasive cutaneous device, 3M SpotOn, using Zero Heath-Flux method, continuously measure core temperature. This prospective study compare the accuracy of Zero-Heath-Flux to oesophagal temperature (30 patients) and to artery catheter (20 patients) in adult patients during surgery.

Every patients undergoing heavy surgery had their central temperature monitoring, through an arterial catheter if the surgery required it (30 patients in this arm), otherwise the investigators used an oesophagus tube (20 patients). We also monitored every 50 patients with a non-invasive method 3M spot on (Zero-heath-flux technic) in order to measure its fiability and validity during the surgery.

Inclusion Criteria:

• Patients scheduled to undergo general anaesthesia for gut surgery lasting more than 2 hours
• Patients with core temperature monitored with oesophagal probe only (30 patients) or with oesophagal probe and PICCO device (20 patients)
• Patients without opposition to this study after informations given

Exclusion Criteria:

• Patients with frontal cutaneous decay wich avoid using 3M Spot-on
• Patients whom oesophagal probe was prohibited (oesophagal varices, oesophagal surgery)
• Pregnant women or breast-feeding, women who may become pregnant unless adequate contraceptive measures