An esophageal heat exchange tube will be inserted in anesthetized surgical patients. Each patient will have 30 minutes of cooling (circulating fluid at 7 degrees C) and 30 minutes of warming (42 degrees C) with 15-minute recovery break in between. The primary outcome will be heat transfer, determined from inflow and outflow temperatures and fluid flow rate for cooling and warming modes.

The ECD is made with medical-grade silicone and has 3 ports; 2 coolant ports and a central port. The coolant ports of the ECD are connected to external heat exchanger while a third, central lumen simultaneously allows gastric decompression and drainage. The ECD can be inserted like a standard gastric tube.

The aim of this prospective, interventional study is to quantify heat transfer during warming and cooling using the Esophageal Cooling Device in anesthetized patients having non-cardiac surgery.

An esophageal heat exchange tube will be inserted in anesthetized surgical patients. Each will have 30 minutes of cooling (circulating fluid at 7 degrees C) and 30 minutes of warming (42 degrees C) with 15 -minute break in between; the order of the cooling and warming will be randomized. The primary outcome will be heat transfer, determined from inflow and outflow fluid temperatures and fluid flow rate assessed for both cooling and warming modes.

Inclusion Criteria:

• Elective non-cardiac surgery;
• Age 18-80 years;
• Surgery expected to last >2 hours;
• General anesthesia with endotracheal Intubation;
• Volatile anesthesia;
• BMI < 38 kg/m2;
• ASA physical status 1-3.

Exclusion Criteria:

• Weight < 45 kg;
• Unstable blood pressure;
• Known esophageal deformity or evidence of esophageal trauma or esophageal disease that in the opinion of the attending anesthesiologist precludes safe use of ECD.