Influence of respiration on recordings of lower esophageal sphincter pressure in humans.

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 Further studies were done using the hand withdrawn station pull-through technique with simultaneous quantitation of inspiratory depth.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.