Oesophageal pressure-flow metrics in relation to bolus volume, bolus consistency, and bolus perception

Background: The utility of combined oesophageal pressure-impedance recording has been enhanced by automation of data analysis. Objective: To understand how oesophageal function as measured by automated impedance manometry (AIM) pressure-flow analysis varies with bolus characteristics and subjective perception of bolus passage. Methods: Oesophageal pressure-impedance recordings of 5 and 10 ml liquid or viscous swallows and 2 and 4cm solid swallows from 20 healthy control subjects (five male; 25-73 years) were analysed. Metrics indicative of bolus pressurization (intrabolus pressure and intrabolus pressure slope) were derived. Bolus flow resistance, the relationship between bolus pressurization and flow timing, was assessed using a pressure-flow index. Bolus retention was assessed using the ratio of nadir impedance to peak pressure impedance (impedance ratio). Subjective perception of bolus passage was assessed swallow by swallow. Results: Viscosity increased the bolus flow resistance and reduced bolus clearance. Responses to boluses of larger volume and more viscous consistency revealed a positive correlation between bolus pressurization and oesophageal peak pressure. Flow resistance was higher in subjects who perceived bolus hold up of solids. Conclusions: Bolus volume and bolus type alter oesophageal function and impact AIM analysis metrics descriptive of oesophageal function. Perception of bolus transit was associated with heightened bolus pressurization relative to bolus flow.