The hypothesis that forced-air warming preserves core temperature better than circulating-water mattresses was tested in: (a) 16 adults undergoing major maxillofacial surgery, including radical node resection and flap reconstruction; (b) 53 adults undergoing hip arthroplasty, having ≈25% of their body surface area available for warming; (c) 20 infants undergoing minor maxillofacial surgery; and (d) 10 young children undergoing pelvic or femoral osteotomies. Patients having each type of surgery were randomly assigned to forced-air warming (≈40°C) or conductive warming using a full-length circulating-water mattress at 40°C. Forced-air warming was applied to the legs of the adults undergoing maxillofacial surgery and to one arm, the shoulders, and the neck in the adults undergoing hip arthroplasty; a U-shaped, tubular forced-air cover was positioned around the pediatric patients. Core temperatures increased in all patients given forced-air warming and decreased or remained constant in those without active warming. Furthermore, we needed to decrease the temperature of the warmer from high to medium (≈37°C) in most patients assigned to forced-air warming to prevent hyperthermia. After 15 h of anesthesia, rectal temperatures in the adults undergoing maxillofacial surgery were 3.4“C higher in the forced-air group (P < 0.01). After 4 h of anesthesia, esophageal temperatures had increased 0.8 ± 0.5”C in the patients warmed with forced-air and decreased 0.8 2 0.3“C in those warmed by circulating-water mattresses (P < 0.01). Rectal temperatures in the infants undergoing maxillofacial surgery decreased 0.3 ± 0.1 ”C in both the forced-air and circulating-water groups after premedication with midazolam. Core temperatures then decreased an additional ≈0.4“C in each group during the first 45 min of anesthesia, but after 165 min of anesthesia, were 1.3”C higher in the patients warmed with forced-air (P < 0.01). Esophageal temperatures in the children undergoing orthopaedic surgery decreased ≈0.5“C in each group during the first 60 min of anesthesia. Temperatures subsequently increased in the forced-air group and decreased in those given circulating water. After 150 min of anesthesia, core temperatures were 1.6”C higher in the patients warmed with forced air (P < 0.01). These data indicate that forced-air warming is more effective than circulating water in preventing intraoperative hypothermia in infants, children, and adults.
Address reprint requests to Andrea Kurz, MD, Department of An International Anesthesia Research Society.esthesia and Intensive Care, University of Vienna, Austria.
© 1993 International Anesthesia Research Society