New insights into pharyngo-esophageal bolus transport revealed by pressure-impedance measurement
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Introduction: Pharyngeal propulsion, strength of peristalsis and esophago-gastric junction (EJG) resistance are determinants of esophageal bolus transport. This study used pressure-impedance methods to correlate pharyngo-esophageal function with the esophageal bolus trajectory pathway and pressures generated during bolus transport. Methods: Pharyngo-esophageal pressure-impedance measurements were performed in 20 healthy adult controls. Pharyngeal automated impedance manometry was performed to derive pharyngeal swallow function variables. The esophageal time of nadir impedance (TZn) was used to track bolus trajectory pathway. The inflexion, or flow stasis point (FSP), of the trajectory curve was determined as were the pressures within the bolus (PZn) above and below the FSP. The size of 20mmHg isocontour defect measured the integrity of the peristaltic wave. Results: For viscous boluses, weaker pharyngeal bolus propulsion correlated with the FSP being located higher in the esophagus. Pressure within the bolus was observed to increase at the FSP and below the FSP in a manner that correlated with the magnitude of esophageal peak pressures. Larger 20mmHg isocontour defects were associated with lower pressures within the bolus at the FSP and below. Conclusion: The FSP of the bolus trajectory pathway appears to represent a switch from bolus propulsion due to pharyngeal mechanisms to bolus propulsion due to esophageal mechanisms. 20mmHg isocontour defects significantly reduce bolus driving pressure at or below the FSP.