I read the paper by Fletcher and colleagues with interest. (Gut 2004;53:168–73.)

In their earlier study,¹ the group reported the existence of an unbuffered acid pocket in 60% of study subjects which extended for approximately 2 cm (median length) in the postprandial period. Furthermore, when pre and postprandial pH step up distances were measured and correlated with clips fixed to the oesophagus, this acid pocket was localised to a region “just above” the squamocolumnar junction. It would be fair to infer then, that if a pH sensor was firmly implanted just above the squamocolumnar junction, it would record a prolonged acid reflux event in the postprandial state as the probe would be continuously bathed in acid from this reservoir. This is distinct from intermittent acid reflux events due to transient lower oesophageal sphincter relaxations or straining.

In their more recent paper,² greater acid exposure at the squamocolumnar junction was found compared with …