PREOPERATIVE ANXIETY AND VOLUME AND ACIDITY OF GASTRIC FLUID IN PEDIATRIC PATIENTS

Abstract

S298 INTRODUCTION: Pediatric anesthesia is associated with a high risk of pulmonary aspiration of gastric contents [1]. Although H2-blockers can reduce the acidity and volume of gastric fluid, they have no effect on the already existing gastric fluid. Increased sympathetic tone by preoperative anxiety would affect secretion of gastric fluid and gastric empty time. Our purpose in this study is to clarify how preoperative anxiety of pediatric patients and their parents affects the acidity and volume of the gastric fluid. METHODS: After obtaining informed consent, we studied 43 pediatric patients aged 3 to 6 years who underwent elective minor surgery under general anesthesia starting in the early morning. At preanesthetic visit, the parents were asked to complete two sets of the visual-analogue scale, on the night before surgery (VAS-N) and the other the next morning before premedication (VAS-M), with regard to the level of anxiety of the patients (range 0 = "no anxiety at all", 10 = "extremely anxious"). Midazolam (0.2 mg/kg-1) was rectally administered 30 min. earlier to the induction. After induction of anesthesia with sevoflurane in nitrous oxide and oxygen, gastric content was aspirated in the supine position, both lateral positions, and in the Trendelenburg and reverse Trendelenburg positions. Volume of gastric content and pH was measured by a graduated cylinder and pH meter (Cyberscan 100, Iuchi, Shingapor), respectively. Patients whose VAS-M was less than 5 were considered the low-anxiety group (L-group), and the others were the high-anxiety group (H-group). Statistical analysis was performed by Mann-Whitney U test and p value less than 5% was considered significant. RESULT: Numbers of patient of the L-group and the H-group were 24 and 19 respectively. Ages and body weights were comparable. In the H-group, the VAS-N score was significantly higher than in the L-group (P<0.05). The increase in VAS-M from VAS-N was significant higher in the H-group (p<0.05). There was no difference in distribution of pH of gastric fluid. The mean volume of gastric fluid in the L-group (0.47 +/- 0.26 ml.kg-1) was significantly higher than in the H-group (0.28 +/- 0.16 ml.kg-1) (P<0.05) DISCUSSION: The cephalic phase of gastric secretion, stimulated by sight, smell, thought and so on, can originate in the cerebral cortex or in the appetite center and be transmitted to the stomach through the vagal nerve. In a highly anxious state, the cephalic phase of gastric secretion would be suppressed due to focusing on anesthesia or surgery. In addition, the increased sympathetic tone disturbs gastric secretion through the adrenergic neurons in the splanchnic nerve. The result suggests that relief of preoperative anxiety does not help to reduce risk of aspiration of gastric contents. Therefore, anxiolysis and reduction of gastric fluid should be achieved by different procedures.