Fructose administration increases intraoperative core temperature by augmenting both metabolic rate and the vasoconstriction threshold

Abstract

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·kg -1·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 35.7° ± 0.4°C (mean ± SD) in the fructose group and 35.1° ± 0.4°C in the saline group (P = 0.001). The vasoconstriction threshold was greater in the fructose group (36.2° ± 0.3°C) than in the saline group (35.6° ± 0.3°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 0.4°C. Epinephrine, norepinephrine, and angiotensin II concentrations and plasma renin activity were similar in each treatment group. CONCLUSIONS: Preoperative fructose infusion helped to maintain normothermia by augmenting both metabolic heat production and increasing the vasoconstriction threshold. © 2006 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.