EFFECTS OF 2-HOUR, 4-HOUR AND 12-HOUR FASTING INTERVALS ON PREOPERATIVE GASTRIC FLUID PH AND VOLUME, AND PLASMA-GLUCOSE AND LIPID HOMEOSTASIS IN CHILDREN

We evaluated 105 randomly-selected unpremedicated children aged 1 14 y ears to determine the effects of a 2-, 4- and 12-h preoperative fastin g interval on the preoperative gastric fluid pH and volume, and plasma glucose and lipid homeostasis. Each child undergoing elective surgery ingested a large volume approximately 10 ml/kg b.w.) of apple juice a nd then fasted for 2, 4 or 12 h before the estimated induction of anae sthesia. After induction of anaesthesia, gastric fluid was aspirated t hrough a large-bore, multiorifice orogastric tube. Plasma concentratio ns of glucose, total ketone bodies, non-esterified fatty acid (NEFA), triglycerides, and cortisol were measured at the time of induction to evaluate the fasting interval effects on preoperative plasma glucose a nd lipid homeostasis. There were no significant differences between th e three groups in either gastric fluid volume or pH. In addition, ther e were no significant differences between the groups with respect to t he proportion with a pH < 2.5 and volume > 0.4 ml/kg b.w. Neither plas ma concentrations of glucose, triglycerides, nor cortisol at the time of anaesthetic induction differed between the three groups. Both 4 and 12 h nil per os (NPO) caused an increase in lipolysis, which was pres umably a compensatory mechanism to maintain normoglycaemia. The plasma NEFA and total ketone bodies concentrations were therefore significan tly higher in these two fasting intervals than in 2 h NPO. These data suggest that a 2-h NPO, after a large volume of ingested apple juice, may offer additional benefits by preventing an increase in lipolysis d uring the fasting interval without either increasing the volume of gas tric fluid or decreasing the gastric pH. However, we must emphasize th at these limited results should not be extrapolated either to infants or to the general population.