Effect of forced-air warming blanket position in elective lumbar spine surgery: Intraoperative body temperature and postoperative complications

BACKGROUND: Perioperative hypothermia is linked to multiple postoperative complications including increased surgical bleeding, surgical site infection, myocardial events, and increased length of hospital stay. The purpose of this study is to determine the effects of forced-air warming blanket position, above the shoulders versus under the trunk/legs, on intraoperative core body temperature and perioperative complications in elective lumbar spine surgery. METHODS: After IRB approval, patients were enrolled in a consecutive fashion and randomized to either upper body (Group I) or lower body (Group II) groups. Primary outcomes were intraoperative body temperature, incidence of hypothermia, postoperative complications, and infection. Secondary outcomes included blood loss, operative time, and length of stay. RESULTS: Seventy-four patients were included (Group I, 38; Group II, 36, mean age 60.7 years, 54% of male). Average patient follow-up was 69 ± 33.6 days in Group I and 67 ± 34.6 days in Group II. Average intraoperative body temperature was 35.7 in Group I and 35.8 in Group II (P = 0.27). Incidence of critical hypothermia (T < 35°C) was 18.4% and 11.1% in Groups I and II, respectively (P = 0.52). Incidence of mild hypothermia (T: 35°C–36°C) was 34.2% and 30.56% in Groups I and II, respectively (P = 0.81). Separately, pooled analysis comparing average body temperature and incidence infection demonstrated a relationship between mild hypothermia and infection (P = 0.03). CONCLUSION: Compared to using a lower body Bair Hugger under the patient, using standard upper body Bair Hugger may be associated with increased surgical site infection. Given equivalent body warming, we recommend using the lower body Bair Hugger to avoid infection.