Fig. 4.
Comparison of percentage retention (the percentage of the liquid test meal retained within the stomach) calculated based on the fluorescence data (using two methods of data analysis) and the paracetamol data. (A) Graph showing percentage retention values as functions of time. Blue dots (“Fluorescence – direct”) represent retention values calculated using the direct method of data analysis (see Eq. (8)). Black triangles (“Fluorescence – S(t)”) represent retention values calculated via fitting of the fluorescence vs. time curves (see equations (2-7)). Data for participant 9 was excluded from the fluorescence retention calculations due an error in the fluorescence data collection. Data for participant 7 was excluded from the paracetamol retention calculations, as a steady state elimination region was not observed in this dataset (which is required for accurate calculation of percentage retention based on the paracetamol data [19]). (B-D) Box plots showing the times at which 75% (B), 50% (C) and 25% (D) retention were observed using each technique. For each box, the red line represents the median value, the upper and lower edges of the blue box represent the 25th and 75th percentiles, the whiskers extend to the most extreme data points (excluding outliers), and outliers are indicated by red ‘+’ symbols. As above, data for participants 7 and 9 were excluded from the paracetamol and fluorescence boxes respectively. P-values represent the results of Wilcoxon signed rank tests comparing the fluorescence retention times against the corresponding paracetamol retention times (for which the values for participants 7 and 9 were excluded from all datasets to allow a paired analysis).