Effect of head position on the dynamics of the upper esophageal sphincter and pharynx

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Abstract
Due to limitations in available technology it has been difficult to obtain data on upper esophageal sphincter (UES) and pharyngeal (P) function under varying physiologic conditions. We used a manometry system with solid-state intraluminal transducers, including a circumferential sphincter transducer, and computer analysis to measure pressure changes in UES and P during wet (5 ml H2O) swallows as the head was moved through a 75 degree arc in nine normal volunteers. UES residual pressure increased markedly and duration of UES relaxation decreased with increasing head extension. Similar decreases were also seen with time between P peak and both UES nadir and UES end. There were no changes in either pharyngeal peak pressures or the duration of the pharyngeal contraction. Head extension produces major changes in UES relaxation and UES/P coordination. These effects may be clinically important when feeding neurologically impaired patients.