Analysis of 24-hour esophageal pressure and pH data in unselected patients with noncardiac chest pain. Fourty-four unselected patients with noncardiac chest pain were studied using conventional manometry with additional edrophonium provocation and 24-hour ambulatory esophageal pH and pressure recording with a system developed by our group. New, fully automated techniques of statistical analysis of the complete set of esophageal pressure and pH signals were used to examine the temporal relation between pain, esophageal motility disturbances, and gastroesophageal reflux. The analysis used the 97.5th percentile of amplitude and duration of all esophageal contractions in each patient as well as a chi 2 test of the distribution of contraction types to determine whether a pain episode was related to abnormal motility or not. The edrophonium test results were positive in 2 patients. Only 25 patients (56.8%) had at least one pain episode (total, 111 episodes) during 24-hour recording. Thirty-three percent of the pain episodes were related to reflux and 23.4% to abnormal motility, and 43.2% were not related to an esophageal function disturbance. In the patient-oriented analysis in this study, it was required for a positive correlation that the symptom index (percentage of related pain episodes) was higher than 75%. It was found that the pain was related to reflux in 2 patients (4.6%), to reflux and motor abnormalities in 4 (9.2%), and to motor abnormalities in 2 patients (4.6%). In 36 patients (81.8%), no relation with an esophageal abnormality could be established, either because the patients had no pain during the 24-hour study, or because the pain seemed unrelated to reflux or abnormal motility. 