Gastric emptying of a solid–liquid meal measured with 13C octanoic acid breath test and real-time ultrasonography: a comparative study

Abstract

OBJECTIVES: The 13C octanoic acid breath test (OBT) has been proposed as a reliable noninvasive test to measure gastric emptying. OBT has been compared with scintigraphy; however, there are no data comparing it with gastric emptying measured with real-time ultrasonography (RUS) The aim of the study was to correlate gastric emptying of a solid–liquid meal, with OBT and RUS simultaneously evaluated in a group of normal volunteers. METHODS: A total of 14 normal subjects ingested a standard test meal (one scrambled egg with two slices of white bread, 10 g of butter, and 300 ml of tap water). The egg yolk was mixed with 0.1 ml of 13C octanoic acid. Breath samples for 13CO 2 analysis were collected in breath bags and were analyzed by means of isotope-selective nondispersive infrared spectrometry (IRIS). RUS was simultaneously performed by calculating the antral area following a previous validated method. Breath samples and antral area were taken at baseline and every 15 min after the meal during the first 2 h and every 30 min for another 2 h. Lag time (T lag) and gastric half emptying time (T 1/2) were calculated for OBT and RUS. Data were analyzed by the Student’s t test for paired data, correlation coefficient, and regression line. RESULTS: The results show a statistically significant longer T lag and T 1/2 for OBT in comparison with RUS ( p < 0.001). A significant correlation and positive regression line was computed between OBT and RUS for T lag and for T 1/2. CONCLUSIONS: Our results show that OBT overestimates gastric emptying parameters of a solid–liquid meal in comparison with RUS. However, both techniques give data in good correlation. Because OBT is less operator-dependent than RUS, it may be useful in comparative gastric emptying studies.