Intrasubject variability of gastric emptying in the critically ill using a stable isotope breath test

SummaryBackground and aimsIsotope breath tests are increasingly used to evaluate the effects of prokinetic drugs on gastric emptying. The aim was to assess intrasubject variability in gastric emptying, when using an isotope breath test in the critically ill.MethodsA retrospective analysis of data was undertaken in 12 patients who had gastric emptying measurements on consecutive days using a 13C-octanoic acid breath test. The gastric emptying coefficient – GEC (a global index for the gastric emptying rate), and the t50 (calculated time for 50% of meal to empty) were calculated, together with the coefficient of variability for these parameters. Data are mean (SD).ResultsNeither GEC (day 1: 3.3 (0.8) vs. day 2: 3.1 (0.6); P = 0.31) nor t50 (day 1: 127 (43) min vs. day 2: 141 (48) min; P = 0.46) were significantly different between the two days. Intrasubject variability was less for GEC (15.6%) than for t50 (31.8%).ConclusionThere is only modest intrasubject variability in GEC measurements using the 13C-octanoic acid breath test in critically ill patients. As such, it may be an acceptable measurement tool to assess the effects of prokinetic drugs in this group.