24-h Recording of Intragastric pH: Technical Aspects and Clinical Relevance

Abstract

van Herwaarden MA, Samsom M, Smout AJPM. 24-h recording of intragastric pH: technical aspects and clinical relevance. Scand J Gastroenterol 1999;34 Suppl 230:9-16.Background: Information about gastric acid secretion and gastric acidity can be obtained using several techniques but, presently, continuous intragastric pH recording is probably the one applied most frequently. This paper aims to review the technical aspects and some important applications of intragastric pH monitoring in research and clinical practice. Methods: Literature review. Results: Most studies on intragastric pH are performed with either glass or antimony electrodes. Optimal measurement of 24-h intragastric pH requires accurate calibration of the pH measuring system, exact positioning of the pH electrodes, and a sufficient sample rate. Depending on the aim of the study the results of intragastric pH monitoring are expressed either as median H activity or as median pH values. Gastric acidity shows a circadian rhythm, modified by buffering meals and nocturnal duodenogastric reflux. In health, age, gender and smoking habits are known to influence gastric acidity. In duodenal ulcer disease an increased gastric acidity is found and in patients with gastric ulcer gastric acidity is decreased. In GERD, no relation between reflux oesophagitis and gastric acidity is found. Helicobacter pylori affects intragastric pH most pronounced during acid inhibitory therapy, both in DU patients and in healthy subjects. In the absence of H. pylori the effect of proton-pump inhibitors on intragastric pH is much less than in the presence of the microorganism, whereas the effect of ranitidine on intragastric pH is barely affected by the H. pylori status. Conclusions: Despite some limitations, intragastric pH monitoring provides important information about gastric acidity.

Postprocessing In Vitro Digestion Challenge To Evaluate Survival of Escherichia coli O157:H7 in Fermented Dry Sausages

“…The effect is dual and results from the interaction between the existing basic food moieties and the acids released in the stomach (31,40), as well as from the hydrolysis of proteins by pepsin, with concurrent release of amines. This buffering effect was evidenced in the present study when gastric challenge was carried out under static conditions, with no pH adjustment, and resulted in a moderate decrease of acidity.…”

Review article: methods of measuring gastric acid secretion

“…They can be connected to a recording device directly, or indirectly by radiotelemetry. 40 The positioning of the electrode is vital as different parts of the stomach may have different pH. Fackler et al demonstrated that positioning the probe in the fundus was the optimal position for measurement of gastric pH, whereas Cilluffo et al showed in postprandial states pH measurement in the antrum was more dependable.…”

“…Hence, some concerns have been raised in using pH values as a measure of gastric acid. 40 It should be borne in mind that gastric pH neither gives a quantitative evaluation of the volume of acid secretion nor does it necessarily correlate to gastric acid secretion as several factors like food, gastric emptying, bicarbonate secretion, dilutional effect of saliva and intestinal secretions can all influence the pH of gastric liquid.…”

The Effects of Increasing Doses of Ranitidine on Gastric pH in Children

“…Thus, gastric pH measurement provides important pharmacodynamic information regarding the efficacy of anti-secretory medications like ranitidine. 18 In a study of infants, ranitidine 2 mg/kg/dose administered every eight hours was more effective than 2 mg/kg, 3 mg/kg or even 4 mg/kg administered every 12 hours in terms of total time with gastric pH values < 3 and < 4. 19 In another infant study, ranitidine 5 mg/kg/dose orally increased gastric pH for 9-10 hours.…”