Incidence of hypothermia and factors affecting variation in core body temperature in patients undergoing arthroscopic surgery of the hip.

Perioperative hypothermia (below 36°C) has been associated with post-operative morbidity. The aim of this study was to determine the incidence of post-operative hypothermia in hip arthroscopy patients and factors affecting perioperative body temperature variation. A prospective audit of 50 consecutive patients undergoing hip arthroscopy for a variety of pathologies was carried out. The final sample size was 46 due to missing data in 4 patients. Core body temperature was measured with a nasopharyngeal temperature probe at the induction of anaesthesia and at the end of the procedure. Other recorded variables were type of warming blanket, ambient theatre temperature and duration of surgery. It was noted whether the patient was shivering immediately post-operatively. The following demographic details were recorded : age, sex, body mass index and the American Society of Anaesthesiologists physical status score. The statistical analysis was performed with Stata® 12 (StataCorp LP, College Station, Texas) by use of a conditional regression model to calculate associations between post-operative body temperature and other variables. The series included 30 female and 16 male patients aged 18 to 57 years (mean 35), with a mean BMI of 26.4 (standard deviation 4.2). Overall incidence of hypothermia below 36°C was 61%. Results of the conditional regression analysis suggested a positive association between post-operative body temperature and pre-operative body temperature (P< .001). Incidence of hypothermia in hip arthroscopy patients is high (61%). We recommend warming patients pre-operatively with forced air warming devices to reduce this incidence. Level of evidence : IV.