1. Date of download: 6/28/2016 Copyright © American College of Chest Physicians. All rights reserved. From: Upper Esophageal Sphincter and Gastroesophageal Junction Pressure Changes Act to Prevent Gastroesophageal and Esophagopharyngeal Reflux During Apneic Episodes in Patients With Obstructive Sleep Apnea Chest. 2010;137(4):769-776. doi:10.1378/chest.09-0913 Concurrent polysomnographic and manometric tracings from a typical OSA event are shown. (A) This tracing represents a 60-s period from the polysomnogram recording. The normally fluctuating nasal airflow and pressure become flat, indicating an apneic event. There is persistent effort seen in the chest and abdomen belts, confirming the obstructive nature of the apnea. There is no rapid eye movement, and both submental and leg muscle tone continue to persist. These findings indicate a non-rapid eye movement sleep stage. There is an absence of Δ waves and the presence of sleep spindles, indicating stage 2 sleep. Therefore, in this example, the OSA event occurred during stage 2 sleep and lasted 26 s. This obstructive event ended with arousal, seen in the EEG channels and confirmed with the return of normal nasal airflow. (B) Concurrent high-resolution manometric contour plot tracing during the apneic period seen in (A). This tracing represents a 60-s period. The horizontal axis represents time, and the vertical axis represents axial location along the pharynx, UES, esophagus, GEJ, and stomach. Pressure values are coded through a color scale. Color bands denoting the UES and GEJ high pressure zones are readily identified, as are phasic changes in pressure with respiration. The time of the OSA event is shown as a blue box at the bottom of the tracing. (C) Line tracing and e-sleeve pressure tracings of pressure data seen in (B). Figure shows selected pressure recordings from individual recording sites used to generate the contour plot. In addition, the e-sleeve shows the highest instantaneous pressure value over multiple sensors located at the level of the GEJ, to avoid artifacts from recording from a single sensor that is displaced during respiration. The end-inspiratory intraesophageal pressure progressively decreases from the beginning to the end of the apneic period. On the other hand, the end- inspiratory GEJ pressure progressively increases from the beginning to the end of the apneic period. (D) UES pressure response during the apneic period. Tracing is similar to that in (C), except that the e-sleeve is now positioned over the region of the UES. The end-inspiratory UES pressure increases progressively from the beginning to the end of the apneic period. EMG = electromyogram; EOG = electroophthalomogram; ESO = esophageal body; GEJ = gastroesophageal junction; LES = lower esophageal sphincter; L- EOG = left electroophthalmogram; L-LEG = electromyogram on the left leg; R-EOG = right electroophthalmogram, R-LEG = electromyogram on the right leg; OSA = obstructive sleep apnea; Sao 2 = arterial oxygen saturation; UES = upper esophageal sphincter. Figure Legend: