Fructose Administration Increases Intraoperative Core Temperature by Augmenting Both Metabolic Rate and the Vasoconstriction Threshold

Background: The authors tested the hypothesis that intravenous fructose ameliorates intraoperative hypothermia both by increasing metabolic rate and the vasoconstriction threshold (triggering core temperature).

Methods: Forty patients scheduled to undergo open abdominal surgery were divided into two equal groups and randomly assigned to intravenous fructose infusion (0.5 g middle dot] kg-1 middle dot] h-1 for 4 h, starting 3 h before induction of anesthesia and continuing for 4 h) or an equal volume of saline. Each treatment group was subdivided: Esophageal core temperature, thermoregulatory vasoconstriction, and plasma concentrations were determined in half, and oxygen consumption was determined in the remainder. Patients were monitored for 3 h after induction of anesthesia.

Results: Patient characteristics, anesthetic management, and circulatory data were similar in the four groups. Mean final core temperature (3 h after induction of anesthesia) was 35.7degrees] +/- 0.4degrees]C (mean +/- SD) in the fructose group and 35.1degrees] +/- 0.4degrees]C in the saline group (P = 0.001). The vasoconstriction threshold was greater in the fructose group (36.2degrees] +/- 0.3degrees]C) than in the saline group (35.6degrees] +/- 0.3degrees]C; P < 0.001). Oxygen consumption immediately before anesthesia induction in the fructose group (214 +/- 18 ml/min) was significantly greater than in the saline group (181 +/- 8 ml/min; P < 0.001). Oxygen consumption was 4.0 l greater in the fructose patients during 3 h of anesthesia; the predicted difference in mean body temperature based only on the difference in metabolic rates was thus only 0.4degrees]C. Epinephrine, norepinephrine, and angiotensin II concentrations and plasma renin activity were similar in each treatment group.