Application of isotope-selective nondispersive infrared spectrometry (IRIS) for evaluation of [13C]octanoic acid gastric-emptying breath tests: comparison with isotope ratio–mass spectrometry (IRMS)

摘要

Suitability of isotope-selective nondispersive infrared spectrometry (IRIS) for evaluation of [13C]octanoic acid gastric-emptying breath test was assessed and compared with standard isotope ratio–mass spectrometry (IRMS). The estimated bias of IRMS and IRIS measurements of baseline-corrected 13CO2exhalation amounted to ± 0.1 and ± 0.6 Δδ values (n = 360), respectively. In breath tests performed on 60 diabetic patients, the gastric emptying parameters were calculated by nonlinear regression analysis of the time course of 13CO2exhalation: half-emptying time ( t 1/2,breath, 90 ± 39 min), lag phase ( t lag,breath, 34 ± 27 min), and gastric emptying coefficient (GEC, 2.9 ± 0.5). A reasonable linear correlation was found between the two methods ( y = IRIS, x = IRMS) with respect to Δδ values ( y = 0.35 + 0.92 x , r = 0.985, S y | x = ±0.6, n = 1116) and a rather good agreement of the computed gastric emptying parameters was obtained ( t 1/2,breath: y = 0.99 x + 4.06, S y | x = ±6.3; t lag,breath: y = 0.97 x + 0.96, S y | x = ±3.4; GEC: y = 0.97 x ? 0.01, S y | x = ±0.09).