The Evaluation of Gastric Emptying Using the 13 C-Acetate Breath Test in Neurologically Impaired Patients - A Focus on the Stomach Function and Morphology

PURPOSE

We explored factors affecting gastric emptying in neurologically impaired (NI) patients using the 13C-acetate breath test.

METHODS

Twenty-four NI patients were classified by the presence of gastroesophageal reflux disease (GERD), which was treated by fundoplication plus gastrostomy, or the absence of GERD, which was treated by gastrostomy alone, along with gastric malposition involving cascade stomach and organoaxial gastric volvulus (OGV). Gastric emptying parameters (GEPs), which were the emptying half time (T 1/2 , minute), the lag phase time (T lag , minute), and the gastric emptying coefficient (GEC), were measured before and after surgery. We evaluated the relationship between GEPs and GERD, gastric malposition, and surgical intervention. All data were expressed as the median (interquartile range).

RESULTS

The T1/2 and GEC of patients with OGV were significantly worse than in those without OGV before surgery (T1/2 with OGV: 241.3 [154.9, 314.3] vs. T1/2 without OGV: 113.7 [105.2, 151.4], p = 0.01, GEC with OGV: 3.19 [2.46, 3.28] vs. GEC without OGV: 3.65 [3.24, 3.90], p = 0.02). GERD and cascade stomach were not associ ated with GEPs. The GEPs of all NI patients showed no significant difference between before and after surgery. The surgical change in T1/2 (ΔT 1/2 ) in the patients with OGV was significantly lower than in those without OGV (ΔT1/2 with OGV: -47.1 [-142.7, -22.1] vs. ΔT1/2 without OGV: -3.78 [-26.6, 12.0], p = 0.03).

CONCLUSION

Stomach malposition, such as OGV, seems to affect gastric emptying and may be improved by surgi cal intervention.

Influence of regular exercise on gastric emptying in healthy men: a pilot study

Functional gastrointestinal disorders (FGIDs), including functional dyspepsia (FD), are common chronic disorders even in the younger population. Physical activity is advocated for patients with FGIDs, although the evidence is insufficient. We investigated the association between the intensity of regular exercise and gastric emptying to determine the effect of physical activity on dyspeptic symptoms. Thirty healthy individuals were selected and divided into three groups (low, moderate, and high) using the index of total exercise intensity in a week. Gastric emptying was evaluated by the ¹³C-acetate breath test. Gastroesophageal reflux symptoms, dyspeptic symptoms, stool forms, scores of anxiety and depression, and scores of sleep quality were also compared. Baseline scores of gastroesophageal reflux symptoms, anxiety, depression, and sleep quality were not different among the three groups. Gastric emptying was significantly faster in low-intensity exercise group than the moderate-intensity exercise group. Although the presence of loose stool and alcohol consumption were also associated with the intensity of regular exercise, these variables were not confounders. In conclusion, the intensity of regular exercise was independently associated with gastric emptying in healthy individuals. These baseline data would be useful for consideration of an optimal exercise intervention for the treatment of FD.

On the validity of the (13) C-acetate breath test for comparing gastric emptying of different liquid test meals: a validation study using magnetic resonance imaging

BACKGROUND

(13) C-acetate breath testing (BT) is applied to assess and compare gastric emptying of liquid meals. Gastric half-emptying times (t50 ) from BT show offsets compared to t50 values from γ-scintigraphy and ultrasonography. Linear transformations have been proposed to correct these offsets. This investigation critically validates the BT for the assessment of liquid gastric emptying by using simultaneously recorded meal and total gastric content volume emptying data from magnetic resonance imaging (MRI).

METHODS

Data were collected during a recently published double-blind, randomized, cross-over MRI gastric emptying study of three (13) C-labeled enteral formulas differing in protein sources (PMID: 24699556). Breath testing-derived t50 was computed with the analysis methods commonly applied in gastric emptying research, i.e., the exponential-beta function and the Wagner-Nelson (WN) method, respectively.

KEY RESULTS

Breath testing t50 values from exponential-beta function and WN method showed a positive and negative offset to MRI data, respectively. Linear regression detected low concordance between MRI and both BT methods revealing meal specific and emptying rate-dependent offsets. The WN method showed worse agreement and correlation with MRI emptying data. Breath testing rather reflected meal volume than total gastric content volume emptying.

CONCLUSIONS & INFERENCES

This validation study indicates that the (13) C-acetate breath test may not be applied to compare gastric emptying of arbitrary liquid meals without prior validation by imaging methods. t50 values from BT are biased by (i) the properties of the meal and (ii) the selected method used for (13) CO2 exhalation analysis. No linear transformation common for all meals was applicable to correct the offsets between BT and MRI.

Evaluation of periesophageal nerve injury after pulmonary vein isolation using the (13)C-acetate breath test

Background

Pulmonary vein isolation (PVI) has become an important option for treating patients with atrial fibrillation (AF). Periesophageal nerve (PEN) injury after PVI causes pyloric spasms and gastric hypomotility. This study aimed to clarify the impact of PVI on gastric motility and assess the prevalence of gastric hypomotility after PVI.

Methods

Thirty consecutive patients with AF underwent PVI under luminal esophageal temperature (LET) monitoring. The ¹³C-acetate breath test was conducted before and after the procedure for all patients (PVI group). Gastric emptying was evaluated using the time to peak concentration of ¹³CO₂ (T_max). This test was also conducted in another 20 patients who underwent catheter ablation procedures other than PVI (control group).

Results

The number of patients with abnormal T_max (≥75 min) increased from seven (23%) to 13 (43%) and from three (15%) to five (25%) after the procedure in the PVI group and control group, respectively. The mean T_max was longer after PVI than before PVI (64±14 min vs. 57±15 min, p=0.006), whereas there was no significant difference before and after the procedure in the control group. However, no significant difference in ΔT_max was observed between the two groups (p=0.27). No patients suffered from symptomatic gastric hypomotility.

Conclusions

Asymptomatic gastric hypomotility occurred more often after PVI. However, the average impact of PVI on gastric motility was minimal.

Nissen fundoplication for gastroesophageal reflux: No deterioration of gastric emptying measured by C-acetate breath test

Aim:

To study the gastric emptying 30 days after laparoscopic Nissen fundoplication (NF) in gastroesophageal reflux.

Materials and Methods:

Three patients were evaluated with ¹³C-acetate breath test (ABT) performed pre and post-NF. The liquid test meal consisted of Racol^™ mixed with ¹³C-acetate.

Results:

In the patient without neurological impairment (NI), the preoperative t_½ex and t lag were 0.900 and 0.510 hours, respectively. The postoperative t_½ex and t lag were 0.959 and 0.586 hours, respectively. In one patient with NI, the preoperative t_½ex and t lag were 1.828 and 1.092 hours, respectively. The postoperative t_½ex and t lag were 2.081 and 1.025 hours, respectively. In the other patient with NI, the preoperative t_½ex and t lag were 2.110 and 0.980 hours, respectively. The postoperative t_½ex and t lag were 1.118 and 0.415 hours, respectively.

Conclusions:

Our findings suggest that ¹³C-ABT parameters did not worsen in any of the children after laparoscopic NF.

Influence of chronic ethanol consumption on extra-pancreatic secretory function in rat

BACKGROUND

The usefulness of the typical direct methods involving duodenal intubation, such as the secretin and secretin-cholecystokinin tests, in the diagnosis of exocrine pancreatic dysfunction is widely accepted. However, these diagnostic tests tend to be avoided because of their technical complexity and the burden on patients. Recently, a simple breath test was developed for assessment of exocrine pancreatic function employing 13C-dipeptide [i.e., benzoyl-L-tyrosyl-[1-13C] alanine (Bz-Tyr-Ala)]. Although alcohol abuse causes pancreatic damage in humans, this has been unclear in rats.

AIMS

The aim of the study is to evaluate the effect of ethanol exposure beginning at an early age on extra-pancreatic secretory function in rats.

MATERIALS AND METHODS

Twelve female rats of the F344 strain aged 12 months were used. Seven rats were fed on a commercial mash food with 16% ethanol solution (Japanese Sake) as drinking-fluid since at 29 days of age (ethanol group). The remaining five rats were fed on a nutrient-matched isocaloric diet with water as drinking-fluid (control group). After 24-hr fasting, rats are orally administrated 1cc of water containing sodium 13C-dipeptide (5 mg/kg) and housed in an animal chamber. The expired air in the chamber is collected in a breath-sampling bag using a tube and aspiration pump. The 13CO2 concentration is measured using an infrared spectrometer at 10-min interval for 120 min and expressed as delta per mil.

RESULTS

The breath 13CO2 level increased and peaked at 20 min in both two groups. In general, 13CO2 excretion peaked rapidly and also decreased sooner in ethanol rats than in control rats. The mean value of the maximal 13CO2 excretion is 34.7 per mil in ethanol rats, greater than in control rats (31.4 per mil), but the difference did not reach the statistically significance.

CONCLUSION

Chronic ethanol feeding beginning at an early age does not affect extra-pancreatic secretory function in rats.

Removal of ovarian hormones affects the ageing process of acetate metabolism

BACKGROUND

Despite a close association between gastrointestinal motility and sex hormones, it has been unknown whether ovarian hormones affect absorption and metabolism of nutrients. The aim of this study is, therefore, to evaluate metabolism of acetate in rats with age and the influence of ovariectomy on its change.

METHODS

Fourteen female rats of the F344 strain were used, and 13C-acetate breath test was performed at 2, 7 and 13 months of age. Seven rats were ovariectomized at three weeks of age (ovariectomy group) and the remaining seven rats were studied as control group. After 24-hr fasting, rats are orally administrated 1ml of water containing sodium (13)C-acetate (100mg/kg) and housed in an animal chamber. The expired air in the chamber is collected in a breath-sampling bag using a aspiration pump. The (13)CO(2) concentration is measured using an infrared spectrometer for 120 min and expressed as delta per mil.

RESULTS

The breath (13)CO(2) excretion increased with time and peaked 30 min in control rats. In ovariectomized rats, thee peak time of (13)CO(2) excretion was prolonged to 40 min at 7 and 13 months of age. Cmax was significantly higher at 2 months of age but lower at 4 months of age in ovariectomized rats than in control rats. Those of two groups became equal at 7 months of age.

CONCLUSIONS

From the viewpoint of acetate metabolism, removal of ovarian hormones might make rats to be precocious ones and accelerate ageing.