Respiratory-related fluctuations in lower esophageal sphincter pressure recording were examined by evaluating both axial respiratory motion and inspiratory compression of the high pressure zone in 20 volunteers. High-pressure zone length measurements were made by motorized slow and rapid pull-through techniques. Further studies were done using the hand withdrawn station pull-through technique with simultaneous quantitation of inspiratory depth. During quiet respiration, there was 0.6 +/- 0.2 cm axial motion in the abdominal portion and 0.4 +/- 0.1 cm movement in the thoracic portion of the high-pressure zone. A hypothetical waveform was constructed based upon this calculated axial motion. There was good agreement between hypothetical and actual pressure profiles except for the distal segment of the high-pressure zone where deep inspiration increased peak pressures to levels 2-3 times those of quiet respiration. It is concluded, therefore, that both axial motion and inspiratory compression contribute to the high-pressure zone waveform.

Modern computer design offers the opportunity to rapidly and objectively analyze the large quantity of data obtained during prolonged intraesophageal monitoring. The purpose of this study is: (1) to describe a rapid automated technique for acquisition and analysis of esophageal parameters, using a microcomputer; and (2) to compare computerized versus manual analysis of physiograph recordings. Ten normal subjects underwent 24-hr computerized monitoring of intraesophageal function, including: (1) pH recording at 5 and 10 cm above the lower esophageal sphincter (LES); (2) pharyngeal contraction; (3) esophageal contraction at 5 and 10 cm; (4) posteriorly directed LES pressures; and (5) gastric pressure. Segments from several studies were chosen for comparison of physiograph data with that obtained by computer. No significant differences were found except for the number of esophageal contractile events. This difference stems from a problem of shifting baseline related to subject position. Thus, the computer can be used for analysis of large quantities of data obtained from prolonged esophageal monitoring.