Reduced vascular volume might influence body temperature by diverting heat flow from peripheral tissues to the central organs. We therefore tested the hypothesis that mild hypovolemia helps to prevent intraoperative hypothermia in pediatric patients. Methods: Twenty-two pediatric patients (aged 1-3 yr) undergoing prolonged minor surgery were randomly assigned to conservative (n ‫؍‬ 12) or aggressive (n ‫؍‬ 10) perioperative fluid management. The conservative group fasted 8 h before surgery and

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... eceived a crystalloid at 1 ml · kg ؊1 · h ؊1 during surgery. The aggressive group was allowed to drink liquids until 3 h before surgery and was given a maintenance crystalloid at 8 ml · kg ؊1 · h ؊1 . Anesthesia was induced and maintained with halothane in nitrous oxide. Ambient temperature was kept near 25°C, but the patients were not actively warmed. During recovery from anesthesia, additional fluid was given to the conservative group so that perioperative fluid totaled 9.5 ml · kg ؊1 · h ؊1 in both groups. Results: Intraoperative body weight remained unchanged in the aggressive group and decreased only 1% in patients managed conservatively. Heart rate was slightly greater in the conservative group (107 ؎ 9 vs. 95 ؎ 4 beats/min, P ‫؍‬ 0.002), but blood pressure was similar. Esophageal temperature in patients whose fluid was managed conservatively increased significantly, by 0.4 ؎ 0.3°C, to 37.1°C; in contrast, temperature in the aggressive group decreased significantly, by 0.4 ؎ 0.2°C, to 36.4°C (P < 0.001 between groups). Temperatures remained significantly different 1 h after surgery. Conclusions: Conservative fluid management, which decreased body weight by only 1%, prevented reduction in core body temperature, presumably by reducing dissipation of metabolic heat from the core thermal compartment to peripheral tissues.