Intraoperative glucose administration influences respiratory quotient during paediatric anaesthesia

Background: Oxidation of carbohydrates and fat yields respiratory quotients (RQ) of 1.0 and 0.7 respectively. Maintained or increased blood glucose co ncentrations are usually seen during paediatric anaesthesia and surgery eve n without glucose administration. The aim of the present study tvas to eval uate whether an intraoperative glucose infusion influences the RQ as an ind ication of a different metabolic preference in comparison to a glucose-free fluid regime. Methods: Eighteen children between 0.5 and 24 months of age were studied du ring anaesthesia with controlled ventilation, oxygen in air,isoflurane, thi opentone, atracurium and fentanyl. Oxygen consumption and carbon dioxide pr oduction were measured using indirect calorimetry All children received Rin ger acetate as needed; in addition, nine children were given glucose 10%, 3 ml kg(-1) h(-1), corresponding to 300 mg kg(-1) h(-1). Blood samples for a nalyses of glucose, lactate, free fatty acids and ketones were taken before and during surgery. Results: RQ was significantly higher in the children given glucose 0.92+/-0 .08, compared to 0.81+/-0.06 in the children without glucose (P<0.01). Oxyg en consumption tended to be higher, although not significantly so, in patie nts without glucose infusion. Energy expenditure was 1.70+/-0.29 kcal kg(-1 ) h(-1), without significant group differences. Higher blood glucose concen trations during surgery were found in the children given glucose. Conclusions: Our results indicate a higher glucose oxidation rate in patien ts given glucose during surgery.