24-h recording of intragastric pH: Technical aspects and clinical relevance

Background: Information about gastric acid secretion and gastric acidity ca n be obtained using several techniques but, presently, continuous intragast ric pH recording is probably the one applied most frequently. This paper ai ms to review the technical aspects and some important applications of intra gastric pH monitoring in research and clinical practice. Methods: Literatur e review. Results: Most studies on intragastric pH are performed with eithe r glass or antimony electrodes. Optimal measurement of 24-h intragastric pH requires accurate calibration of the pH measuring system, exact positionin g 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 circ adian rhythm, modified by buffering meals and nocturnal duodenogastric refl ux. In health, age, gender and smoking habits are known to influence gastri c acidity. In duodenal ulcer disease an increased gastric acidity is found and in patients with gastric ulcer gastric acidity is decreased. In GERD, n o relation between reflux oesophagitis and gastric acidity is found. Helico bacter pylori affects intragastric pH most pronounced during acid inhibitor y 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 le ss than in the presence of the microorganism, whereas the effect of ranitid ine on intragastric pH is barely affected by the H pylori status. Conclusio ns: Despite some limitations, intragastric pH monitoring provides important information about gastric acidity.