This prospective, randomized, single-center study compares intraoperative heat loss at the core temperature level in patients scheduled for direct anterior total hip arthroplasty under general anesthesia and who will or will not, according to randomization, receive one hour of pre-warming with a pulsed air thermal blanket prior to anesthesia induction.

In patients undergoing surgery, intraoperative hypothermia can occur because of anesthesia-induced inhibition of thermoregulation and heat loss associated with the patient's exposure to an environment maintained at a temperature below normal skin temperature.

Randomized trials show that even mild hypothermia results in serious complications, including surgical wound infection, coagulopathy and increased blood transfusions, and delayed postoperative recovery.

All products used during general anesthesia profoundly alter thermoregulatory control, reducing the activation thresholds of the main defenses against cold, which are the closure of the arteriovenous shunt and the generation of shivering. Impaired thermoregulation, combined with a cold operating room environment and direct-anterior hip surgical approach and exposure, causes hypothermia in almost all unheated patients.

The body core temperature is finely tuned to maintain an average of 37°C by balancing heat gain and loss. The nasopharynx is an excellent alternative to patient core temperature monitoring when esophageal monitoring is excluded for surgical reasons or blocked by an airway protected by an airway device.

Inclusion Criteria:

• ASA 1-2-3
• Scheduled for direct anterior-approached total hip replacement surgery under general anesthesia

Exclusion Criteria:

• pregnant women

• patients with:

  1. peripheral neuropathy or other severe neurological pathology
  2. immunosuppression
  3. chronic renal insufficiency or severe hepatic insufficiency
  4. major congenital or acquired hemostasis disorders
  5. craniofacial dysmorphism or anatomical alterations of the upper airways
  6. known thermoregulatory disorders

• patients with a preoperative body temperature > 37.5°C.

Unblinded