Ambulatory 24-hour esophageal pH monitoring. Technology searching for a clinical application.

The development of commercially available ambulatory 24 hour pH monitoring systems has expanded the potential use of this technique. In this article the use of these instruments is reviewed and direct comparisons between different techniques are made. Both the transnasal pH probes and the telemetric capsule have potential advantages and disadvantages for both the physician and the patient. Problems with the interpretation of pH recordings are discussed. A symptom index is developed in an attempt to provide a numerical assessment of the direct association between reflux events and symptoms in each individual patient.