The present proposal intends to determine the effect of prewarming on body temperature in the perioperative period of patients submitted to digestive system surgeries and to evaluate a perioperative "Zero-Heat-Flux Cutaneous" body temperature thermometer in comparison to the standard care (temporal thermometer in the preoperative and postoperative, and esophageal in the intraoperative period). This is a randomized clinical trial consisting of three groups, namely: preoperative warming of patients with blanket and cotton sheet (control); preoperative warming with forced air warming system for 20 minutes (Intervention 1), and participants submitted to preoperative warming with a forced air warming system for 30 minutes (Intervention 2).

The present proposal intends to determine the effect of prewarming on body temperature in the perioperative period of patients submitted to digestive system surgeries and to evaluate a perioperative "Zero-Heat-Flux Cutaneous" body temperature thermometer in comparison to the standard care (temporal thermometer in the preoperative and postoperative, and esophageal in the intraoperative period). This is a randomized clinical trial consisting of three groups, namely: preoperative warming of patients with blanket and cotton sheet (control); preoperative warming with forced air warming system for 20 minutes (Intervention 1), and participants submitted to preoperative warming with a forced air warming system for 30 minutes (Intervention 2)

Inclusion Criteria:

• Patients aged 18 years and over at the time of data collection
• Patients submitted to elective oncological surgery of the digestive, curative or palliative system, with anesthesia duration of at least one hour

Exclusion Criteria:

• Subjects with body temperature equal to or greater than 38 ºC at the time of admission to the Surgical Center
• Patients submitted to video laparoscopic or minimally invasive surgeries