Reliability of the time to maximal [¹³CO₂] excretion and the half-[¹³CO ₂] excretion time as a gastric emptying parameter: Assessments using the Wagner-Nelson method

Abstract

In the [ 13 C]-octanoate breath test, two popular parameters have been used to quantify gastric emptying rates, namely the time to the maximal [ 13 CO2] excretion (Tmax) and the time to the half-[ 13 CO2] recovery (T1/2b). Although each of Tmax and T1/2b is closely correlated with the scintigraphic half-emptying time, the two parameters occasionally indicate different judgments on a gastric emptying rate. In this study, to clarify which of the two parameters is more reliable, Tmax and T1/2b were compared to the "reference" parameters calculated using the Wagner-Nelson method, which allows accurate estimation of a time-course of gastric emptying from breath data. Ten healthy male volunteers underwent the breath test after ingestion of a muffin meal (320 kcal) containing 100 mg [ 13 C]-octanoate. Breath samples were collected at 15-min intervals for 6 h. According to the conventional analytical algorithm, Tmax and T1/2b were mathematically calculated. By applying Wagner-Nelson analysis to the breath test, the time-percent gastric retention curve was generated and the half-emptying time (T1/2WN) was determined. T1/2WN was more closely correlated with Tmax (r=0.954, P<0.0001) than with T1/2b (r=0.782, P=0.008). Tmax was significantly correlated with the percent gastric retention value in the early (t=0.25 and 0.5 h), the middle (t=1.0 and 1.5 h), and the late (t=2.0 h) postprandial phase. T1/2b was significantly correlated with the gastric retention value in the middle and the late phase, but not with the gastric retention value in the early phase. The present results show that T1/2b has limited capability to reflect gastric emptying in the early postprandial period, suggesting that Tmax is more reliable than T1/2b as a gastric emptying parameter.

Stable isotope breath tests for assessing gastric emptying: A comprehensive review

“…emptying time is expressed as (-1/k)ln(1 -2 -1/β ){ln(β)}/k and the lag phase as (-1/k)ln(1 -2 -1/β ). (Takahashi et al, 2006;Sanaka et al, 2007b;Sanaka et al, 2008;Iwase et al, 2009;Shindo et al, 2009;Mishima et al, 2009). In this context, Tlag is replaced by Tmax afterward in the present review.…”

“…This finding is quite understandable, considering that the CPDR[t] curve changes minimally while the PDR[t] curve does dynamically in the early phase (Zai et al, 2009). Next, T1/2b would be prone to mistakenly judge a "normal" emptying to be "delayed" in case that the PDR[t] curve exhibits a very gentle descending slope Shishido et al, 2002;Lee et al, 2000;Sanaka et al, 2007b); in such a case, we speculates that the retention, rather than a real delay in the emptying, makes the pulmonary […”

“…Some investigators, however, are skeptical about the primacy of T1/2: rather, they are confident that T1/2b is inferior to Tmax as an emptying measure based on the following observations. First, T1/2b is less sensitive than Tmax in detecting an early postprandial change in gastric emptying (Sanaka et al, 2007b). This finding is quite understandable, considering that the CPDR[t] curve changes minimally while the PDR[t] curve does dynamically in the early phase (Zai et al, 2009).…”

“…Generally, T1/2b seems more popular than Tmax, despite a lack of tangible supportive evidence (Sanaka et al, 2007b). Some investigators, however, are skeptical about the primacy of T1/2: rather, they are confident that T1/2b is inferior to Tmax as an emptying measure based on the following observations.…”

Camostat Mesilate, Pancrelipase, and Rabeprazole Combination Therapy Improves Epigastric Pain in Early Chronic Pancreatitis and Functional Dyspepsia with Pancreatic Enzyme Abnormalities

“…Further studies will be warranted to determine whether the early phase of gastric emptying such as AUC 5 value was associated with pancreatic enzyme abnormalities in FD patients. In addition, previous studies have reported that solid test meals [43] and liquid meals [44][45][46] were used for assessment of the early phase of gastric emptying. In the future, we have to compare the early phase of gastric emptying evaluated by solid test meals with liquid test meals.…”