Strain induced augmentation of upper oesophageal sphincter pressure in children.

The hypothesis that troublesome oesophagopharyngeal reflux arises from defective upper oesophageal sphincter response to straining has been evaluated in 53 children aged two to 81 months (median 13) referred with symptoms thought to be related to gastro-oesophageal reflux. Spontaneously occurring pharyngeal, upper oesophageal sphincter, oesophageal body, and gastric pressures were analysed after feeding. Inspiratory strain was the most common spontaneously occurring strain (172 episodes), defined as an oesophageal body inspiratory negative pressure dip at least twice the size of the normal inspiratory wave. Overall, during inspiratory strain, upper oesophageal sphincter pressure was significantly higher than before straining (p < 0.01) (5 v 27 mm Hg, p < 0.01). Sustained strains defined as increases in gastric and oesophageal body pressure for two to 20 seconds were also common (149 episodes) and when compared with just before straining, also augmented upper oesophageal sphincter pressure (60 v 39 mm Hg, p < 0.01). The vigour of straining, estimated as increase of gastric pressure, correlated significantly with the degree of augmentation of upper oesophageal sphincter pressure (p < 0.05). Children with and without evidence of troublesome oesophagopharyngeal reflux showed no difference in upper oesophageal sphincter response patterns to straining. Failure of augmentation of upper oesophageal sphincter tone in the face of strain induced increases of oesophageal body pressure is probably a secondary factor in the production of oesophagopharyngeal reflux in children.