Preoperative Warming, Hypothermia and Functional Recovery in Total Hip Arthroplasty

Effect of Preoperative Warming on Intraoperative Hypothermia and Postoperative Functional Recovery Outcomes in Direct Anterior-approached Total Hip Arthroplasty: a Randomized Clinical Trial

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.

Patients undergoing total hip replacement surgery by anterior approach, with general anesthesia and continuous core body temperature measurement via nasopharyngeal thermic probe. Patients recruited for surgery who will not receive the 30 minutes of preoperative warming through pulsed air thermal coverage.

Patients undergoing total hip replacement surgery by anterior approach, with general anesthesia and continuous core body temperature measurement via nasopharyngeal thermic probe. Patients recruited for surgery who will receive the 30 minutes of preoperative warming through pulsed air thermal coverage.

Patients enrolled in surgery who will not receive 30 minutes of pulsed air thermal blanket warming prior to induction of anesthesia (3M™ Bair Hugger™ Adult Integral Blanket, Model 300 Dimensions: 213 cm x 91 cm)

Variation of core body temperature during surgery, i.e. the difference between the temperature at the time of induction of general anaesthesia and the minimum temperature recorded during the procedure, as well as its evolution over time.

The occurrence of side effects related to hypothermia (cardiovascular, infectious and hemorrhagic complications)

Inclusion Criteria: ASA 1-2-3 Scheduled for direct anterior-approached total hip replacement surgery under general anesthesia Exclusion Criteria: pregnant women patients with: peripheral neuropathy or other severe neurological pathology immunosuppression chronic renal insufficiency or severe hepatic insufficiency major congenital or acquired hemostasis disorders craniofacial dysmorphism or anatomical alterations of the upper airways known thermoregulatory disorders patients with a preoperative body temperature > 37.5°C.

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