ELECTROGASTROGRAPHIC POWER RATIO IN HUMANS IS NOT RELATED TO CHANGES IN ANTRUM-SKIN DISTANCE BUT TO ANTRAL MOTILITY

It is not clear whether the power increase in electrogastrography (EGG ) after meal or water ingestion reflects increases in gastric motility or gastric distension bringing the stomach closer to the electrodes o n the abdominal skin surface. We recorded EGG and real-time ultrasonog raphy simultaneously before and after 150-ml water ingestion in 17 hea lthy volunteer. We calculated gastric power, by spectral analysis of E GG by the maximum entropy method, for 400 s before and after water ing estion, and calculated their ratio (power ratio). We calculated, using sonography: the number of antral contractions before and after water ingestion, the motility index after water ingestion, the distance betw een the antrum and the abdominal skin surface before and after water i ngestion, and the ratio of these distances (distance ratio). The numbe r of contractions was positively correlated with gastric power before water ingestion, and the antrum-skin distance was negatively correlate d with gastric power both before and after water ingestion. The motili ty index after water ingestion was positively correlated with both gas tric power after water ingestion (Spearman's rank correlation r = 0.49 2. P = 0.0498) and the power ratio (r = 0.615. P = 0.0141). There was no correlation between the distance ratio and the power ratio. These r esults suggest that the power increase in EGG induced by water ingesti on does not reflect the approach of the antrum to the abdominal surfac e, but rather, reflects antral motility after water ingestion.