Measuring Gastric Emptying Phases

Five ml stomach aspirate was sampled at baseline, 30, 60 and 120 min, and aliquoted appropriately for analyte profiling. The (1–¹³C)-acetate/octanoate technique was employed to measure both the liquid and semi-solid phases of gastric emptying as previously described^{(37 (link),38 (link))}. Each test solution was labelled with 150 mg (1–¹³C)-sodium acetate and 100 mg (1–¹³C)-sodium octanoate. Breath samples were then collected every 5 min after the ingestion of the liquid test meal and were analysed for isotopic enrichment by an isotope ratio mass spectrometer (Iso-Analytical) with an online gas chromatographic purification system. All δ values were expressed v. the Pee Dee Belemnite international standard and related to the baseline value. This was converted to the percentage (¹³C) recovery per hour and to the cumulative recovery after 2 h, which acts as a marker of gastric emptying^{(38 (link),39 (link))}.