PERIOPERATIVE NORMOTHERMIA TO REDUCE THE INCIDENCE OF SURGICAL-WOUND INFECTION AND SHORTEN HOSPITALIZATION

Background. Mild perioperative hypothermia, which is common during maj or surgery, may promote surgical-wound infection by triggering thermor egulatory vasoconstriction, which decreases subcutaneous oxygen tensio n. Reduced levels of oxygen in tissue impair oxidative killing by neut rophils and decrease the strength of the healing wound by reducing the deposition of collagen, Hypothermia also directly impairs immune func tion. We tested the hypothesis that hypothermia both increases suscept ibility to surgical-wound infection and lengthens hospitalization. Met hods. Two hundred patients undergoing colorectal surgery were randomly assigned to routine intraoperative thermal care (the hypothermia grou p) or additional warming (the normothermia group). The patients' anest hetic care was standardized, and they were all given cefamandole and m etronidazole. in a double-blind protocol, their wounds were evaluated daily until discharge from the hospital and in the clinic after two we eks; wounds containing culture-positive pus were considered infected. The patients' surgeons remained unaware of the patients' group assignm ents. Results. The mean (+/-SD) final intraoperative core temperature was 34.7+/-0.6 degrees C in the hypothermia group and 36.6+/-0.5 degre es C in the normothermia group (P<0.001), Surgical-wound infections we re found in 18 of 96 patients assigned to hypothermia (19 percent) but in only 6 of 104 patients assigned to normothermia (6 percent, P = 0. 009). The sutures were removed one day later in the patients assigned to hypothermia than in those assigned to normothermia (P = 0.002), and the duration of hospitalization was prolonged by 2.6 days (approximat ely 20 percent) in the hypothermia group (P = 0.01). Conclusions. Hypo thermia itself may delay healing and predispose patients to wound infe ctions, Maintaining normothermia intraoperatively is likely to decreas e the incidence of infectious complications in patients undergoing col orectal resection and to shorten their hospitalizations. (C) 1996, Mas sachusetts Medical Society.