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

Abstract

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. 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 13CO2 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 (Tlag) 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. The results show a statistically significant longer Tlag 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 Tlag and for T(1/2). 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.