A valid, accurate, office based non-radioactive test for gastric emptying of solids

Background - Current breath tests for measurement of gastric emptying of solids are expensive, possibly inaccurate, and require cumbersome calculations. Aims - We wished to validate a simplified solid gastric emptying test using a [¹³C]Spirulina platensis breath test for accurate results relative to scintigraphy. Subjects - Thirty healthy volunteers. Methods - We measured gastric emptying of egg containing [¹³C]S platensis and ^99mTc sulphur colloid by breath ¹³CO₂ and scintigraphy over six hours. A generalised linear regression model was used to predict t(1/2) and t(LAG) by scintigraphy from breath ¹³CO₂ data. The model was cross validated and normative data calculated for a prepacked [¹³C]meal. Results - Regression models using all breath data over six hours, for the first three hours, and for samples at 75, 90, and 180 minutes ('reduced model') predicted t(1/2) and t(LAG) values similar to scintigraphy (t(LAG) 43 (SD 12) min; t(1/2) 100 (20) min). Standard deviations of differences in t(1/2) and t(LAG) between scintigraphy and the 'reduced model' were both 10 minutes. Gastric t(1/2) for the prepacked [¹³G]meal was 91 (15) min (10-90% range: 74-118). Conclusion - The [¹³C]S platensis breath test and a simple formula using breath ¹³CO₂ at baseline, 90, and 180 minutes measured gastric emptying t(1/2) for solids with results that were comparable with scintigraphy.