In children with vomiting, dyspepsia, and feeding problems, gastroesophageal reflux (GOR) and altered gastric emptying are common. We have used electrical impedance tomography (EIT) to study children with suspected gastric emptying disorders. Abnormalities of the gastric emptying curve suggestive of GOR were seen in some, with marked negative or positive shifts related to sharp increases or decreases in intragastric resistance. These findings could represent fluid leaving or entering the stomach, as might occur in GOR. To confirm the origin of the abnormal EIT curves, we devised and in vitro tank test system, and we performed simultaneous 2-h EIT and intraoesophageal pH monitoring after a glucose meal on six patients. In vitro, reflux of > or = 25 ml produced clearly detectable changes on the emptying curves. In vivo, the overall correlation between the times of 42 GOR episodes lasting > or = 1 min detected by pH study and the times of 38 negative peaks due to > or = 15% changes of the maximum intragastric resistivity detected by simultaneous EIT was significant; the correlation was highly significant in four of six patients. When the peaks were used to define GOR episodes on EIT gastric emptying curves, the two methods still showed good agreement. Retrospective examination of 50 patients who had undergone both EIT and 24-h intraoesophageal pH study during their diagnostic workup showed that EIT had a sensitivity of 94.6% and a specificity of 76.9% (with positive and negative predictive values of 0.92 and 0.83, respectively) for the detection of pathological GOR.(ABSTRACT TRUNCATED AT 250 WORDS)