Observational Examination of Thermoregulation in Total Joint Arthroplasty

Peri-operative hypothermia can have deleterious effects. While there is no standard consistent definition within the literature mild hypothermia is commonly defined as a core temperature between 34 and 36 °C. Mild hypothermia has been shown to increase the occurrence of surgical site infections, cardiac morbidity, coagulopathy leading to increased blood loss and transfusion requirements, impaired drug metabolism, and prolonged emergence from anesthesia. In addition, there is evidence that maintaining intra-operative normothermia can shorten hospital length of stay. Despite the fact that intra-operative temperature monitoring and warming are considered standard of care, peri-operative hypothermia in total joint arthroplasty patients remains an issue for several reasons. A large proportion of patient undergoing joint replacement are elderly, making them susceptible to peri-operative hypothermia. In addition, regional anesthesia causes vasodilation and promotes heat flow from the core to the periphery and impairs central and autonomic thermoregulation such that patients receiving neuraxial anesthesia can be particularly susceptible to perioperative hypothermia. Finally, core temperature monitoring is typically not used during regional anesthesia and hypothermia may go undetected for long periods of time.

The primary goal of this study was to examine the incidence of hypothermia during lower extremity arthroplasty. A secondary aim was to identify patient and operative factors associated with hypothermia in order to improve future preventative strategies. Our hypothesis was that peri-operative hypothermia occurs in the majority of patients undergoing lower extremity arthroplasty. In addition, we hypothesized that certain patient and anesthetic factors (such as low body mass index and receiving general anesthesia) would increase the incidence of hypothermia.