Approaches to driving the evolving understanding of lower oesophageal sphincter mechanical function

This article reviews and places into context the development of lower oesophageal sphincter (LOS) manometry, the key technique for researching the mechanics of this region. The first of two major challenges, being able to record sphincter pressure accurately with generally available equipment, was solved by the advent of perfused manometry in the 1960s. The other main challenge was to achieve reliable, continuous recording of LOS pressure, despite the constant movements of the LOS relative to the manometric catheter. Though well documented, this challenge is still poorly understood and prioritised, as many clinical/diagnostic and research manometric studies use methods for LOS manometry that are invalidated by LOS movement. There are two techniques that can record continuously from the LOS, despite its movements: high resolution manometry (HRM), which uses multiple point pressure sensors spaced at 1 cm interval or less, and the sleeve, which is a single long sensor. HRM provides valuable additional information on the varied topography of pressure patterns across the gastro-oesophageal junction and how this can change in an individual, second to second. HRM especially, but also sleeve manometry continue to advance understanding of the mechanics of gastro-oesophageal reflux, to unravel the mysteries of the mechanics of hiatus hernia and the diaphragmatic hiatus, to define why antireflux surgery fails or causes dysphagia, to recognise patients with dysphagia due to isolated defects of LOS relaxation and to test novel therapies for reflux disease directed at LOS function. Ample evidence now exists that accurate monitoring of LOS and gastro-oesophageal junction pressures is important for the diagnostic assessment of many patients and for advancing research into several aspects of the mechanical function of the LOS and its surrounding structures. This evidence now needs to be better reflected in the methods used for routine clinical practice and research.