[Effects of anesthesia, premedication and age on gastric pH and volume]

To investigate the effect of anesthesia on gastric secretion, we measured pH and volume of gastric juice during anesthesia using the following anesthetic techniques: halothane anesthesia in three age groups, halothane without atropine premedication, halothane with thoracic epidural block, and enflurane anesthesia. Halothane anesthesia increased pH in all age groups and the increase in pH was greater in older age groups. Gastric pH also increased in halothane anesthesia group with thoracic epidural block and in enflurane anesthesia group. However, the increase in gastric pH and the decrease in gastric juice volume were not significant in halothane anesthesia group without atropine premedication. These results suggest that the increase in gastric pH during halothane anesthesia is due to parasympathetic nerve block.