title: A new method for determining gastric acid output using a wireless pH-sensing capsule.
abstract: BACKGROUND
  Gastro-oesophageal 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.
  
  
  OBJECTIVE
  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, USA).
  
  
  METHODS
  Twenty healthy subjects underwent conventional GAO studies with a nasogastric tube. Variables impacting liquid meal-stimulated GAO analysis were assessed by modelling 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 radiolabelled 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 basal acid output (BAO) (r = 0.51, P = 0.02), maximal acid output (MAO) (r = 0.72, P = 0.0004) and peak acid output (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.
authors: Digestive Diseases Branch, National Institutes of Health, Bethesda, MD, USA.
authors: D H
authors: DH
authors: Weinstein
authors: S
authors: S
authors: deRijke
authors: C C
authors: CC
authors: Chow
authors: L
authors: L
authors: Foruraghi
authors: X
authors: X
authors: Zhao
authors: E C
authors: EC
authors: Wright
authors: M
authors: M
authors: Whatley
authors: R
authors: R
authors: Maass-Moreno
authors: C C
authors: CC
authors: Chen
authors: S A
authors: SA
authors: Wank
mesh_terms: D000328:Adult; D053704:Capsule Endoscopy / Q000379:methods*; D005260:Female; D005744:Gastric Acid / Q000378:metabolism* / Q000502:physiology; D005745:Gastric Acidity Determination; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D015203:Reproducibility of Results; D055815:Young Adult
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