END-EXPIRATORY PRESSURE BEST APPROXIMATES INTRINSIC LOWER ESOPHAGEAL SPHINCTER PRESSURE - REPORT OF A PATIENT WITH CHEYNE-STOKES RESPIRATION

Lower esophageal sphincter (LES) pressure is routinely measured during esophageal manometry. However, the method of recording LES pressure, of actually taking the measurement, and its clinical usefulness remain areas of debate. Current esophageal manometric systems employ water-perfused catheters or intraluminal transducers, although a recently developed sleeve apparatus is used in a research setting for continuous sphincter pressure monitoring (1). The respiratory effect on intraluminal LES pressure is easily appreciated on manometric tracings obtained by station pull-through (SPT) (2). Because of the respiratory oscillation inherent in the SPT technique, LES pressure may be scored in several ways with reference to gastric baseline pressure: end-expiratory pressure, mid-respiratory pressure, and peak respiratory oscillation (3-5). There is no consensus as to which is preferable. A recent study in cats showed that respiratory-induced oscillations in LES pressure are primarily the result of active diaphragmatic contraction (6). An absence of oscillation in LES pressure was found during periods of central apnea induced by manual hyperventilation. LES pressure during apnea was equal to end-expiratory pressure during spontaneous respiration in the cats. It was concluded that intrinsic LES pressure is best approximated by end-expiratory pressure during spontaneous respiration. This finding is confirmed in a patient we report with Cheyne-Stokes breathing and achalasia who underwent esophageal manometry. LES pressure during periods of central apnea approximated end-expiratory pressure during periods of hyperpnea. © 1990 Plenum Publishing Corporation.