WAGNER‐NELSON METHOD FOR ANALYSING THE ATYPICAL DOUBLE‐PEAKED [¹³CO₂] EXCRETION CURVE IN THE [¹³C]‐OCTANOATE GASTRIC EMPTYING BREATH TEST IN HUMANS

Abstract

1. In the [(13)C]-octanoic acid breath test, the time versus pulmonary [(13)CO(2)] excretion rate curve is analysed using mathematical curve-fitting techniques to calculate gastric emptying parameters. Thus, the goodness-of-fit highly influences the accuracy of the breath test. However, a double-peaked [(13)CO(2)] excretion curve, which occasionally develops owing to the presence of an interval of quiescent gastric emptying (the plateau phase), is likely to be fitted poorly. 2. In pharmacokinetics, the Wagner-Nelson method has been used to describe precisely the absorption kinetics of orally administered drugs and its reliability is independent of the nature of gastric emptying. A recent study has shown the potential of the Wagner-Nelson method to generate a realistic gastric emptying flow curve from [(13)CO(2)] excretion data. In the present report, we have demonstrated that the Wagner-Nelson method can visualize the plateau emptying phase responsible for the cases of double peaks. 3. Wagner-Nelson analysis applied to the breath test described precisely the characteristic emptying pattern of the two emptying phases being interrupted by the plateau phase. Conventional analysis for the breath test failed to detect the plateau phase. 4. The Wagner-Nelson method is a useful tool for analysing atypical double-peaking [(13)CO(2)] excretion curves.

Methods and functions: Breath tests

“…Various mathematical models (e.g. Wagner Nelson method) try to make the 13 C-breath test kinetics comparable to radioscintigraphy curves and adjust for the passage of the 13 C-tracer through the metabolic pathways and for the fixation and loss in the bicarbonate pool [56]. In the author's opinion we should be aware of the differences in the methods but should not adjust for factors we do not measure in order to get similar curves to scintigraphy.…”

To Precisely Describe a Profile of Bizarre Gastric Emptying by Breath Testing

“…Its relevance has recently been validated against the sonographic measurement of liquid GE (6). More recently, it has been suggested that Wagner-Nelson analysis is versatile enough to decipher atypical GE patterns (4). To verify the versatility, we show here that a GE curve prepared by the Wagner-Nelson method can accurately reproduce atypical behavior of GE that is experimentally induced.…”

“…A breath (t) to each time point was calculated manually according to the trapezoidal rule, and C(t)/0.65 at the corresponding time was then added to each AUC(t). A breath (∞) was computed as A breath (4.0) + C(4.0)/0.65 (4,6). A breath (t) and A breath (t) + C(t)/0.65 were divided by A breath (∞).…”

13CO2 breath tests, a tool to assess intestinal and liver function in the ICU?

“…Ritz et al [24] observed a delayed emptying for ICU patients. In 7 out of 30 cases the 13 CO 2 profile either showed bi-phasic peaks or irregular patterns, which implies profound distortions in gastric motility and has to be handled with more elaborate evaluation schemes [25]. Chiolero et al [26], however, reported that the delay of 13 CO 2 release due to absorption and metabolism does not assume major importance in the critically ill patient.…”