Evaluation of 13CO2 enrichment values obtained with an oral breath test under conditions of impaired gastric functioning. (12th June 2017)

• Record Type: Journal Article
• Authors: Vogt, J A; Wachter, U; Radermacher, P; Georgieff, M; König, D; Fabinski, W; Barth, E
• Is Part Of: Journal of breath research. Volume 11:Number 2(2017:Jun.)
• Publication Date: 2017-06-12
• Subjects: breath test -- 13CO2 -- Bayesian statistics -- MCMC -- acetate; Volatile organic compounds -- Analysis -- Periodicals; Clinical chemistry -- Periodicals; Bad breath -- Periodicals; Bad breath -- Treatment -- Periodicals; Bad breath -- Diagnosis -- Periodicals; 616.0756
• DOI: 10.1088/1752-7163/aa726d
• Languages: English
• ISSNs: 1752-7155

Abstract

Abstract: Gastric emptying can be assessed by an oral administration of a 13 C labeled substrate and its response in the expiratory release of the oxidation product 13 CO 2 . Impaired gut function, reflected, for example, in an intolerance against enteral nutrition may delay or discontinue gastric emptying, potentially leading to multiple peaks in the time profile of expiration. The resulting profile cannot be analyzed by the usual data evaluation that is based on a 'beta exponential' (BEX) function. We developed a new approach that better reflects the underlying physiology. It allows a flexible time profile of gastric release and considers a transient 13 CO 2 retention in different compartments as well as an incomplete recovery of 13 CO 2 in the expiration. Parameters that describe the distribution/retention kinetics cannot be determined based on the same breath data that were used to estimate emptying. To enable the determination of the kinetic parameters, they were constrained to match published data using a Bayesian statistical analysis. The applicability of the new model was compared with BEX for healthy subjects. BEX fails to explain the observed data and, compared to the new approach, overestimates the speed of emptying. Predictive accuracy under impaired gastric motility was explored using synthetic data. Only the new approach can reproduce a multiphase absorption profile. When routine benchtop equipment was used for measurements, then the rate-limiting step for precision in the estimate of emptying is the quality in the a priori estimate for kinetic parameters rather than precision in measurements. Only about 80% of the absorbed 13 CO 2 has to be released by expiration. With these features, the new approach promises to widen the applicability of breath tests for gastric emptying.