Perioperative hypothermia brings numerous and recognized postoperative complications. Active warming intraoperatively helps to maintain body temperature in the postoperative period, but there are few studies in Brazil, assessing the effect of prewarming in maintaining normothermia. It is believed that prewarming with forced air warming system keep the body temperature during intra and post-operative. This study aims to evaluate the effect on prewarming maintaining body temperature of patients undergoing elective surgery of Gynecology specialty using the forced air warming system. The study is experimental design, controlled type randomized clinical trial, with simple blinding for patients. Eighty adult patients undergoing gynecological surgery in the art, with a surgical time of at least an hour will be randomized and allocated into experimental groups - prewarming system with forced air warming system for 20 minutes, and control - Prewarming with sheet and blanket for 20 minutes. The patients will be kept warm during the anesthetic-surgical procedure. The measurement of temperature will be using a tympanic thermometer. Participants will be followed from receiving the surgical center to the end of surgery. Data will be recorded in validated instrument. Data analysis will be used the Model Linear Mixed Effects and the Structure Error Auto-Regressive.

Maintaining the patient in the perioperative normothermia is a challenge for surgical and nursing staff. Despite advances in the development of new technologies for the prevention of perioperative hypothermia, this event still happens in the operating room of the health services To prevent patient's body temperature loss, passive and active cutaneous warming methods can be used. Passive methods prevent loss of body heat through the heat transfer block, as blankets, clothes and cotton sheets; however, there is evidence to show that although assist in maintaining body temperature, passive methods alone are not effective.

Active warming methods are effective in keeping the perioperative normothermia. Among the different technologies available we emphasize the circulating water mattress, the forced air warming system and the carbon fiber resistive heating blankets.

Based on these and due to the lack of research in the Brazilian reality on effective measures for the prevention of perioperative hypothermia, among these, prewarming, and the finding guided by the professional experience that just directed investment for the maintenance of body temperature patient in the perioperative period, in health services, justified the conduct of this study.

Inclusion Criteria:

• Aged 18 years;
• Undergoing elective surgery with duration of at least one hour in the gynecological specialty with open technique;
• Under general, regional or combined anesthesia.

Exclusion Criteria:

• Patients with a body temperature above or below 36oC 37,5oC at the reception of the operating room.