Incidence of Hypothermia under Perioperative Standard Thermal Management in Patients With Abdominal Surgery and Its Effect on Surgical Site Infections

Background/Objectives: Perioperative thermal management has been routinely performed to prevent hypothermia induced adverse events including surgical site infections (SSIs). This study aimed to examine the incidence of hypothermia in abdominal surgeries under perioperative standard thermal management and its effect on SSI. Methods: A retrospective cohort study was conducted involving patients who underwent liver (BILI-H), pancreatic (BILI-P), esophageal (ESOP), gastric (GAST), colon (COLN) and rectal (REC) surgery within the period from January to December 2010. Perioperative thermal management was performed using a forced-air warming system in all cases. The following data were collected: the lowest perioperative rectal temperature (pharyngeal temperature in patients undergoing colorectal surgery); 5 patient-related characteristics; 5 surgical procedure-related characteristics; and 5 SSIrelated items. Analysis was performed by calculating: 1) the incidence of each stratified level of hypothermia (mild; 36.0-35.6 degrees C; moderate; 35.5-35.1; and severe; 35.0 or lower) and odds ratios (OR) for risk factors of hypothermia. 2) risk ratios (RR) for SSI risk factors, including hypothermia (36.0 degrees C or lower, 35.5 or lower). SSI was diagnosed based on the criteria defined by the National Healthcare Safety Network. Results: A total of 632 patients (BILI-H: 81; BILI-P: 46; ESOP: 24; GAST: 133; COLN: 134; and REC: 196) were studied. The incidence of each level of hypothermia was as follows: mild 151 patients (24%); moderate 54 patients (9%); and severe 9 patients (1%). The RR for each cause of hypothermia with a body temperature of 36.0 degrees C or lower was as follows: thoracolaparotomy 1.84 (95% Confidence Intervals: 1.22-2.76); lithotomy position: 1.28 (1.141.44); males: 1.55(1.20-1.99); a Body Mass Index (BMI) lower than 18.5: 1.42(1.19-1.70); stoma:1.20 (1.03-1.39, P1⁄40.01) and anemia: 1.13 (1.01-1.26, p1⁄40.038). In multivariate analysis, thoracolaparotomy (OR 4.27, 95%CI 2.01-9.07), lithotomy position (1.97, 1.372.83). BMI lower than 18.5 (2.52, 1.67-3.84), males (1.98, 1.35-2.91) were selected as risk factors for hypothermia with a body temperature of 36.0 or lower. The perioperative body temperature was not correlated with the bleeding volume, duration of surgery, and transfusion volume. The incidence of SSIs was 21% (BILI-H: 16%; BILI-P: 37%; ESOP: 37%; GAST: 14%: COLN: 15%; and REC: 25%). Significant risk factors for SSIs were as follows: contaminated wounds (1.60, 1.05-2.43); emergency surgery (1.27, 0.98-1.64); and stoma construction (1.16, 1.05-1.29). Hypothermia (36.0 or lower, 35.5 or lower) was not selected as a significant risk factor for SSIs [1.02 (0.94-1.12), and 0.99 (0.87-1.13), respectively].