The Effects of Intraoperative Hypothermia on Surgical Site Infection

Abstract

Our primary study objective was to determine whether intraoperative hypothermia predisposes patients to postoperative surgical site infections (SSI) after trauma laparotomy. Although intraoperative normothermia is an important quality performance measure for patients undergoing colorectal surgery, the effects of intraoperative hypothermia on SSI remain unstudied in trauma. A review of all patients (July 2003-June 2008) who survived 4 days or more after urgent trauma laparotomy at a level I trauma center revealed 524 patients. Patient characteristics, along with preoperative and intraoperative care focusing on SSI risk factors, including the depth and duration of intraoperative hypothermia, were evaluated. The primary outcome measure was the diagnosis of SSI within 30 days of surgery. Cut-point analysis of the entire range of lowest intraoperative temperature measurements established the temperature nadir that best predicted SSI development. Single and multiple variable logistic regression determined SSI predictors. The mean intraoperative temperature nadir of the study population (n = 524) was 35.2°C ± 1.1°C and 30.5% had at least 1 temperature measurement less than 35°C. Patients who developed SSI (36.1%) had a lower mean intraoperative temperature nadir (P = 0.009) and had a greater number of intraoperative temperature measurements <35°C (P < 0.001) than those who did not. Cut-point analysis revealed an intraoperative temperature of 35°C as the nadir temperature most predictive of SSI development. Multivariate analysis determined that a single intraoperative temperature measurement less than 35°C independently increased the site infection risk 221% per degree below 35°C (OR: 2.21; 95% CI: 1.24-3.92, P = 0.007). Just as intraoperative hypothermia is an SSI risk factor in patients undergoing elective colorectal procedures, intraoperative hypothermia less than 35°C adversely affects SSI rates after trauma laparotomy. Our results suggest that intraoperative normothermia should be strictly maintained in patients undergoing operative trauma procedures.