The role of prolonged esophageal pH monitoring in the diagnosis of gastroesophageal reflux.

To reassess 24-hour esophageal monitoring and determine if shorter time periods might retain its diagnostic benefits, we studied 16 gastroesophageal reflux (GER) patients and eight controls. Esophageal pH monitoring was performed for 24 hours, with patients in an upright position during the day and supine when retiring. During the 24-hour pH monitoring period, the mean percentage time that pH was less than 4.0 in GER patients, 13.2% +/- 2.9% (SEM), was significantly higher than in normal subjects, 0.7% +/- 0.2% (SEM). Analysis of individual data indicated clear separation of GER patients from normal subjects when in the upright posture, but 25% of GER patients were within the range of the normal subjects when supine (overnight). Three-hour time periods after meals were analyzed. Postprandial pH monitoring, when compared with 24-hour pH monitoring, can identify GER with a 77% sensitivity and a 96% specificity. A 12-hour period (four hours after the dinner meal and eight hours supine) can identify GER with a 94% sensitivity and a 100% specificity. We conclude that (1) 24-hour pH monitoring of the esophagus may have a continuing role in research aspects of GER, (2) 12-hour pH monitoring is a highly accurate test that could be adapted to patients' work schedules or to outpatient telemetry, and (3) postprandial pH testing is a practical, less expensive, and accurate method of diagnosing GER that could be utilized by any gastroenterology diagnostic unit.