The primary objective of this study is to determine if the intraoperative distal esophageal (core) temperature with vitalHEAT warming is non-inferior to upper-body forced-air warming in patients undergoing open colectomy under general anesthesia. This is a randomized study.

Participants will be randomized into one of two groups. Patients assigned to vitalHEAT warming will have the circulating-water sleeve applied to an arm that will not require intravenous access. An esophageal temperature probe will be inserted and connected to the anesthesia machine monitoring system. Intravenous fluids will be warmed to 40-42°C.

As soon as practical after induction, the vitalHEAT warmer will be activated in the appropriate patients and set to "high" which is 42°C

An upper-body forced-air warmer will be positioned over the upper body and exposed arms on patients assigned to forced-air heating. The forced air blower will be set to "high" which is 43°C and activated as soon as practical, usually after prepping and draping.

Patients in both groups will be otherwise draped per surgical routine. Ambient temperature will be maintained near 20°C. Active warming will be maintained until just before extubation. The esophageal temperature probe will be removed, and the patient extubated after emergence from anesthesia. This will conclude the study and subsequent management will be at the discretion of the attending anesthesiologist

Inclusion Criteria:

• Body-mass index 20-36 kg/m2;
• Age 18-75 yrs;
• ASA Physical Status 1-3.

Exclusion Criteria:

• Patient requires an intravenous or arterial catheter distal to the elbow on both arms;
• Serious skin lesions on the hands or arms;
• History of serious vascular disease in the arms;
• Pre-operative fever;
• Contraindication to sevoflurane endotracheal anesthesia.
• Pre-existing neuropathy

5 patients with missing data, including 3 in the warm-water sleeve group and 2 in the forced air group.