A new method for determining gastric acid output using a wireless pH‐sensing capsule

Abstract

BACKGROUND Gastroesophageal reflux disease (GERD) and gastric acid hypersecretion respond well to suppression of gastric acid secretion. However, clinical management and research in diseases of acid secretion have been hindered by the lack of a non-invasive, accurate and reproducible tool to measure gastric acid output (GAO). Thus, symptoms or, in refractory cases, invasive testing may guide acid suppression therapy. AIM To present and validate a novel, non-invasive method of GAO analysis in healthy subjects using a wireless pH sensor, SmartPill® (SP) (SmartPill® Corporation, Buffalo, NY). METHODS Twenty healthy subjects underwent conventional GAO studies with a nasogastric tube. Variables impacting liquid meal-stimulated GAO analysis were assessed by modeling and in vitro verification. Buffering capacity of Ensure Plus® was empirically determined. SP GAO was calculated using the rate of acidification of the Ensure Plus® meal. Gastric emptying scintigraphy and GAO studies with radiolabeled Ensure Plus® and SP assessed emptying time, acidification rate and mixing. Twelve subjects had a second SP GAO study to assess reproducibility. RESULTS Meal stimulated SP GAO analysis was dependent on acid secretion rate and meal buffering capacity but not on gastric emptying time. On repeated studies, SP GAO strongly correlated with conventional BAO (r=0.51, P=0.02), MAO (r=0.72, P=0.0004) and PAO; (r=0.60, P=0.006). The SP sampled the stomach well during meal acidification. CONCLUSIONS SP GAO analysis is a non-invasive, accurate and reproducible method for the quantitative measurement of GAO in healthy subjects. SP GAO analysis could facilitate research and clinical management of GERD and other disorders of gastric acid secretion.

Gastric secretion

“…During the past year, a noninvasive method of measuring gastric acid output (GAO) using a wireless pH sensor Smartpill (Covidien, Mansfield, Massachusetts, USA) has been reported in 20 healthy individuals [13]. Smartpill GAO was calculated using the rate of acidification of an Ensure Plus (Abbott, Columbus, Ohio, USA) liquid meal and was found to correlate with conventional basal acid output, maximal acid output, and peak acid output.…”

Gastric Hypersecretory States: Investigation and Management

“…Under direct endoscopic visualization developed by Oh et al , a single 15-minute sample of gastric juice is collected under fasting and stimulated states to assess for acidity and volume. 26 When compared to conventional gastric aspiration tests, there was excellent agreement when measuring acid concentration with the acceptable difference of ±2.5 mEq/h. However the endoscopic method was found to overestimate acid volume.…”

“…The authors argue the innate critique of under-measuring volume with blind aspiration and increased accuracy with direct visible aspirate. 26 The endoscopic method has the advantage over nasogastric aspiration in that it permits the collection of gastric juice by directly observing the gastric juice and allows the endoscopist to exclude the presence of peptic ulcerations, especially useful in patients with ZES. This method is routinely used at our institution since the test is better tolerated and likely to provide more accurate results.…”

Dyspepsia

“…A wireless pH sensor, the SmartPill, has been compared with conventional gastric acid output measurement, via nasogastric tube, in 20 healthy volunteers [16]. The SmartPill was ingested after an overnight fast, and analysis of gastric acid output proved to be accurate and reproducible, with strong correlations with basal, maximal, and peak acid outputs.…”