Exclusion of the meal period improves the clinical reliability of esophageal pH monitoring

pH Testing: the basics

Esophageal pH testing, first described more than 3 decades ago, has become incorporated in the diagnostic armamentarium of most gastroenterologists. Using commercially available sophisticated equipment and software, the procedure is easy to perform and the analysis of the signals is automated. Nevertheless, users of esophageal pH testing must remain aware of the technical pitfalls that may stand in the way of the acquisition of meaningful results. Esophageal pH monitoring provides quantitative information about the exposure of the distal esophagus to acid. The technique makes it also possible, however, to quantify the correlation between symptom episodes and reflux events. In clinical practice, the latter is often more relevant than information on esophageal acid exposure.

Ingestion of acidic foods mimics gastroesophageal reflux during pH monitoring

Ingestion of acidic foods may produce artifactual drops in pH to < 4 that may be difficult to differentiate from a true acid reflux event. We aimed to evaluate intraesophageal pH changes during the ingestion of acidic food and describe the frequency and implications of acidic food ingestion on ambulatory pH monitoring. Ten normal volunteers (six females; mean age, 34) underwent combined impedance-pH testing with a pH electrode placed 5 cm above the lower esophageal sphincter. Each volunteer received 50 ml each of acidic foods in random order. Nadir and mean pH for 30 sec after ingestion of each substance were recorded. Subsequently 100 randomly selected reflux monitor diaries were reviewed, searching for ingestion of acidic foods, and 100 pH tracings were reviewed to evaluate the impact of including/excluding meal periods on percentage time pH < 4 and DeMeester scores. All foods produced abrupt drops to pH < 4, in 80% of cases exceeding 30 sec. During ambulatory pH monitoring 78% of patients recorded ingestion of at least 1 of the 10 tested substances during meals, the majority admitting ingesting carbonated beverages. Not excluding meal periods would have led to the misinterpretation of 6-16% of tracings, depending on the criteria used to identify abnormal acid exposure. We conclude that ingestion of acidic foods is frequent and carries the risk of overdiagnosing GERD. Current findings support the recommendations to carefully instruct patients to record all oral intake and to exclude meal periods from the analysis.

Comparison of morning and evening administration of rabeprazole for gastro-oesophageal reflux and nocturnal gastric acid breakthrough in patients with reflux disease: a double-blind, cross-over study

AIM

To assess the effect of timing of rebeprazole (RB) 20 mg/d administration on oesophageal acid exposure and nocturnal gastric acid breakthrough (NGAB) in patients with GERD.

METHODS

20 GERD patients received two 7-day treatments of RB in the morning (a.m.) or in the evening (p.m.) hours. The regimens were randomized in a double-blind fashion and separated by a 7-day washout period. The tablets were taken 30 min before standardized meals. A combined (oesophageal & gastric) 24-hour pH monitoring was performed before and on day 7 of each treatment.

RESULTS

Total oesophageal acid exposure was normalized in 10/14 (71.4%) patients with RB p.m. and in 6/15 (42.8%) with RB a.m. RB p.m. significantly decreased the nocturnal supine oesophageal acid exposure vs. RB a.m., 0.2% vs. 3.4%. The mean NGAB duration was significantly shortened with RB a.m. and p.m. vs. the baseline recording, 4.1+/-1.8 and 3.4+/-1.5 hours vs. 7.8+/-1.7 hours.

CONCLUSIONS

Rabeprazole significantly reduced the NGAB duration and significantly increased the mean nocturnal gastric pH; RB p.m. normalized more effectively the total oesophageal exposure than RB-a.m.; RB p.m. provided significantly better control of nocturnal supine gastro-oesophageal reflux than a.m. dosing. These data suggest that administration of a PPI before the evening meal maximizes acid control and would be the preferred dosing schedule in GERD patients, particularly those with nocturnal symptoms.

Monitoring of laryngopharyngeal reflux: influence of meals and beverages

Ambulatory 24-hour double-probe pH monitoring seems to be the best test to measure reflux. Artifacts caused by intake of acid foods and beverages have to be excluded, necessitating a time-consuming manual review of the 24-hour data. Dietary restrictions used to bypass these artifacts would interfere with the normal daily life situation. Therefore, the influence of food and beverages ingested during the monitoring period was studied. Data from 252 patients who underwent double-probe pH monitoring were analyzed, first by visual inspection of the 24-hour tracing and second by leaving out the intake periods. As to the registration of gastroesophageal reflux, the inclusion or omission of meals and beverages hardly influenced the data. However, the registration of laryngopharyngeal reflux was severely biased by intake of food and beverages and other artifacts. Leaving out meals and beverages did not correct for all artifacts. Therefore, we recommend review of each laryngopharyngeal pH drop.