Visceral fat, but not subcutaneous fat, is associated with lower core temperature during laparoscopic surgery

Background Previous studies suggest that lower BMI is a risk factor for intraoperative core hypothermia. Adipose tissue has a high insulation effect and is one of the major explanatory factors of core hypothermia. Accordingly, determining the respective influence of visceral and subcutaneous fat on changes in core temperature during laparoscopic surgery is of considerable interest. Methods We performed a prospective study of 104 consecutive donors who underwent laparoscopic nephrectomy. Temperature data were collected from anesthesia records. Visceral and subcutaneous fat were calculated by computed tomography (CT) or ultrasound. For ultrasound measurements, preperitoneal fat thickness was used as an index of visceral fat. Multiple linear regression analysis was performed at 30, 60, and 120 minutes after the surgical incision to identify the predictive factors of body temperature change. The potential explanatory valuables were age, sex, BMI, visceral fat, and subcutaneous fat. Results BMI (beta = 0.010, 95% CI: 0.001-0.019, p = 0.033) and waist-to-hip ratio (beta = 0.424, 95% CI: 0.065-0.782, p = 0.021) were associated with increased core temperature at 30 minutes after the surgical incision. Ultrasound measured-preperitoneal fat was significantly associated with increased core temperature at 30 and 60 minutes after the surgical incision (beta = 0.012, 95% CI: 0.003-0.021, p = 0.009 and beta = 0.013, 95% CI: 0.002-0.024, p = 0.026). CT-measured visceral fat was also associated with increased core temperature at 30 minutes after the surgical incision (beta = 0.005, 95% CI: 0.000-0.010, p = 0.046). Conversely, subcutaneous fat was not associated with intraoperative core temperature. Male sex and younger age were associated with lower intraoperative core temperature. Conclusions Visceral fat protects against core temperature decrease during laparoscopic donor nephrectomy.