Liquid gastric emptying in the pig: effect of concentration of inhaled isoflurane.

UNLABELLED An animal model of gastric emptying may have use in the study of gastric physiology and pharmacoscintigraphy. The pig has anatomy and physiology similar to that of humans. Our aim was to develop a model of gastric emptying in the pig. It was not possible to perform this study in conscious pigs; therefore, an anesthetic model was developed. METHODS Fifteen studies were performed on 4 pigs (age, 2-6 mo; weight, 20-100 kg). After acclimatization and training, pigs were fasted overnight before the study. Pigs were anesthetized using inhaled isoflurane without the use of injected premedication agents. An orogastric tube was inserted for the administration of a liquid meal, which consisted of (99m)Tc-diethylenetriaminepentaacetic acid either in water (nonnutrient) or with dextrose (nutrient meal). The pig was laterally positioned to enable right lateral dynamic acquisition to be performed. Anesthesia was maintained at 2% +/- 0.5% isoflurane in 4 studies and 0.8% +/- 0.5% in 11 studies (4 nutrient, 7 nonnutrient). RESULTS With 2% +/- 0.5% isoflurane, there was delayed gastric emptying with a mean 50% emptying time (+/-SEM) of 141 +/- 14 min. With 0.8% +/- 0.5% isoflurane, the liquid meal emptied in an exponential manner similar to that of humans, with mean 50% emptying times (+/-SEM) of 30 +/- 7 min (nutrient) and 31 +/- 4 min (nonnutrient). CONCLUSION The results indicate that high-dose anesthesia inhibits gastric emptying, but with low-dose anesthesia a useful pig model of liquid gastric emptying can be developed.