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

OBJECTIVES: The C-13 octanoic acid breath test (OBT) has been proposed as a reliable noninvasive test to measure gastric emptying. OBT has been compar ed 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 s crambled egg with two slices of white bread, 10 g of butter, and 300 mi of tap water). The egg yolk was mixed with 0.1 mi of C-13 octanoic acid. Breat h samples for (CO2)-C-13 analysis were collected in breath bags and were an alyzed by means of isotope-selective nondispersive infrared spectrometry (I RIS). RUS was simultaneously performed by calculating the antral area follo wing 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 rest 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 fo r T-1/2. CONCLUSIONS: Our results show that OBT overestimates gastric emptying param eters of a solid-liquid meal in comparison with RUS. However, both techniqu es give data in good correlation. Because OBT is less operator-dependent th an RUS, it may be useful in comparative gastric emptying studies. (C) 2000 by Am. Cell. of Gastroenterology.