¹³C呼気試験法による胃排出能検査の標準化

抄録

We investigated some important points to standardize ¹³C breath test for gastric emptying. The ¹³CO₂ infrared spectrophotometry analyzer for ¹³C urea breath test to diagnose helicobacter pylori infection needed two breath samples which were collected before and after taking ¹³C substance to measure Δ value. We used a few big sampling bags to collect breath samples before taking test meal. The Δ value between two breath samples collected without ¹³C substance was very small. So there was no problem to regard separate breath samples as same ¹³CO₂ concentration. Deep breathing and using big sampling bag did not influenced because total CO₂ concentration of breath sample was not influenced the Δ value when CO₂ concentration was more than 2%. Therefore the ¹³CO₂ infrared spectrophotometry analyzer was useful to measure breath samples of ¹³C breath test for gastric emptying. Previous studies usually used the half emptying time as a parameter to assume gastric emptying. Recently, the maximum ¹³C excretion time was reported as a good parameter to assume gastric emptying. But in ¹³C-octanoate breath test for solids test meal, the half emptying time and the maximum ¹³C excretion time were considered parameters which were influenced by absorption, metabolism and excretion because there were strong correlations between the total cumulative ¹³C recovery and these parameters. Reproducibility of the parameters in ¹³C-acetate breath test for liquids were better than those in ¹³C-octanoate breath test for solids. So we considered that ¹³C-acetate breath test measured by the ¹³CO₂ infrared spectrophotometry analyzer was a standard method of 13C breath test for gastric emptying and that the maximum ¹³C excretion time was more useful parameter than other parameters. To simplify ¹³C breath test for gastric emptying, we considered to need more studies of normal subjects and patients.