Ambulatory esophageal pH monitoring: new directions.

pH testing remains a commonly used evaluative tool in clinical practice. However, the original tool that included a nasally placed pH catheter was plagued with a variety of shortcomings, primarily the effect of the procedure on patients' lifestyle and thus on reflux-provoking activities. The miniaturization of evaluative techniques in gastroenterology was the impetus for the development of the wireless pH capsule and the SmartPill. These modalities improve patients' tolerability of the required test and provide a unique opportunity for expansion of indications and data collection. The introduction of the multichannel intraluminal impedance with a pH sensor allowed the detection of gastroesophageal reflux that is non-acidic. However, the value of the technique beyond the realm of academic gastroenterology remains to be elucidated. Recently, there was a renewal of interest in Bilitec 2000. The technique, which has never found a clear clinical role, has been recommended as an important tool in evaluating patients who failed proton pump inhibitor therapy. However, data to support its clinical value in this situation have remained scant.