Date Published: June 12, 2019
Publisher: Public Library of Science
Author(s): Ryohei Miyazaki, Sumio Hoka, Ken Yamaura, Akshay Chauhan.
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.
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.
BMI (β = 0.010, 95%CI: 0.001–0.019, p = 0.033) and waist-to-hip ratio (β = 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 (β = 0.012, 95%CI: 0.003–0.021, p = 0.009 and β = 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 (β = 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.
Visceral fat protects against core temperature decrease during laparoscopic donor nephrectomy.
Inadvertent hypothermia is a common intraoperative complication. Hypothermia can lead to adverse patient outcomes, including shivering, increased blood loss and transfusion[1,2], surgical site infection, and reduced clearance of various drugs. These complications may lead to higher mortality rates and longer hospital stays.
This clinical trial was approved by the Ethical Committee for Clinical Studies of the Kyushu University School of Medicine, and was prospectively registered at UMIN Clinical Trial Registry (UMIN000019276). One-hundred-and-twenty patients scheduled for donor nephrectomy were enrolled. All surgeries were performed through the transperitoneal approach in the left renal position. Written informed consent was obtained from each patient prior to participation in this study. Patients with cardiovascular disease, peripheral vascular disease, preoperative hypo- or hyperthermia, an age of 70 years or older, American Society of Anesthesiologists Physical Status classification (ASA-PS) > 2, autonomic disorder, or thyroid disease were excluded. Patients undergoing emergency surgery were also excluded.
Baseline characteristics and perioperative variables of the study participants are shown in Table 1. All surgeries were completed as scheduled. All patients were classified as ASA-PS class 1 or 2. No patient required a blood transfusion, and no surgical site infections occurred. Changes in body temperature are shown in Fig 3. Core temperature decreased for about 1 hour after the surgical incision, and subsequently increased.
The current study showed that visceral fat, but not subcutaneous fat, was strongly associated with core temperature change during laparoscopic surgery.