Mechanisms Preventing Pharyngeal Reflux

"Combined manometric/impedance/pH recording: we will use combined solid-state high-resolution manometry and impedance catheter with 36 circumferential pressure sensors, spaced 1 cm apart, 18 impedance sensor couplets spaced 2 cm apart, 3 pH sensors spaced 7 and 10 cm respectively. The catheter will be introduced trans-nasally.~Concurrent video-pharyngo-laryngoscopy: to monitor concurrently the pharynx and larynx for entry of simulated refluxate we will use a laryngo-pharyngo-scope passed through the other nostril and positioned within the pharynx such that the UES inlet, vocal cords and pyriform sinuses are visualized. The laryngo-pharyngo-scope images will be synchronized with manometric/impedance/pH recordings by importing and superimposing the endoscopic images onto high resolution manometric recordings. A specially designed timer will be superimposed on the video images for durational analyses of endoscopic images."

A 3 mm outer diameter injection tube will be placed through the nose in a fashion that the injection port will be located 5-7cm above the manometrically determined upper border of lower esophageal sphincter (LES). With this arrangement gastroesophageal reflux events will be simulated by intra-esophageal injection of body temperature1/2 normal saline (its ionic nature helps impedance recording and identification of intra-esophageal distribution), 0.1 N HCl. Infused liquid will be colored green using food dye for ease of recognition of pharyngeal reflux. Esophageal clearance will be verified by the presence of an effective peristalsis and return of intra-esophageal impedance and pressure to baseline. Endoscopic views of pharynx will be watched carefully during infusions. At the first sign of reflux, perfusion will be stopped, and participants will be instructed to swallow to avoid any potential airway compromise.