LIMITATIONS OF CONTINUOUS 24-H INTRAGASTRIC PH MONITORING IN THE DIAGNOSIS OF DUODENOGASTRIC REFLUX

Objective: Long term gastric pH monitoring has been proposed to diagno se abnormal duodenogastric reflux. This study analyses the in situ rep roducibility of continuous intragastric pH measurements to assess the influence of artifactual factors in producing spontaneous variations o f pH values that might be frequently misinterpreted as episodes of duo denogastric reflux. Methods: The investigation was carried out in 301 endoscopically proven duodenal ulcer patients (87 female, 214 male, me an age 46 yr). Each patient underwent 24-h gastric pH monitoring with two closely adjacent pH electrodes whose tips were about 2 mm apart. T he two simultaneous pH tracings obtained from each patient were analyz ed with regard to the number, characteristics, and discrepancies of un expected alkalinization waves over the entire circadian cycle. Results : The simultaneous pH tracings of the two-channel datalogger we used r an almost superimposed for more than 23 h in 224 out of 301 (74%) duod enal ulcer patients. Major discrepancies between the two pH tracings o f each recording were obtained in the remaining cases (77/301 = 26%). The most frequent event was represented by unexpected alkalinization w aves that occurred mainly during nighttime and were recorded by only o ne of the two simultaneously measuring electrodes. As few as 16/244 (7 %) patients showed synchronous, unexpected alkalinization waves that o ne might eventually consider to be duodenogastric refluxes. Conclusion s: It is rather common that only one of two closely adjacent pH electr odes placed within the stomach measures longlasting pH elevations, par ticularly during the nocturnal period. This discrepancy is due to a po or in situ, reproducibility of simultaneous pH recordings and indicate s that pH readings might be influenced by interference and artifacts. Thus, the frequent differences between two simultaneous pH readings an d the indirect measurement of the backflow of duodenal contents with l ong term gastric pH-metry do not allow us to rely on this technique to diagnose duodenogastric reflux.