Mer om hvordan fruktose øker kroppvarme (termogenese). I denne er det snakk om å bruke det intravenøst for å unngå at pasienter blir kalde etter operasjoner. Det øker restitusjonsevnen etter operasjonen.
We tested the hypothesis that intravenous fructose ameliorates intraoperative hypothermia both by increasing metabolic rate and the vasoconstriction threshold (triggering core temperature)
40 patients scheduled for 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 hours) 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.
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 (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 hours 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.
Preoperative fructose infusion helped maintain normothermia by augmenting both metabolic heat production and increasing the vasoconstriction threshold.
Fructose is known to provoke the greatest thermogenesis among various carbohydrates.19,20 Fructose also provokes dietary-induced thermogenesis in awake healthy volunteers, and does so far better than glucose.15 We thus tested the hypothesis that intravenous fructose increases metabolic heat production in anesthetized humans. We also tested the hypothesis that fructose, like amino acids, increases the vasoconstriction threshold and thus has a thermoregulatory as well as metabolic contribution to maintaining perioperative normothermia.
CO2 production before infusion showed no significant difference between saline group (147+19 ml min−1) and fructose group (142+16 ml min−1) but increased significantly in the fructose group (201+26 ml min−1) just before induction of anesthesia, compared with the saline group (146+19 ml min−1)(p<0.001). This increased level was maintained for 135 min after induction of anesthesia.