Computer-assisted ambulatory long-term manometry of tubular esophagus

A two-channel 24-hr digital recording of esophageal pressure generates about 20 times more data than an esophageal pH-metry if an appropriate high sampling rate is used and unreduced data are stored. Because of this large amount of data, manual data evaluation is no longer feasible, and a computer-assisted procedure becomes necessary. The system presented here consists of a combined one-channel pH and two-channel pressure probe, a digital data logger, and a computer program for automated evaluation (CAMA). From the pH channel, standard variables (acid exposure time and number of reflux episodes) are calculated. The analysis of the pressure channels is completed in five distinct steps: (1) recognition of contractory events using dynamically recalculated baseline and threshold values, (2) characterization of contractory events, (3) rejection of artifacts, (4) classification of contractions, and (5) integrated analysis (frequency analysis, hourly patterns of single variables, relation to other external variables). This system has been used successfully more than 150 times in more than 120 patients and volunteers; validation was done for contraction characterization by comparing the system's performance with manual analysis and for contraction detection and classification by comparing its performance with a reference standard established from a questionnaire evaluated by international experts. In addition, the reproducibility of esophageal motility has been tested in a series of repeated measurements, and the system has been used to assess the 24-hr pattern of esophageal motility.