Impedance as an adjunct to manometric testing to investigate symptoms of dysphagia: What it has failed to do and what it may tell us in the future

Dysphagia is a common reason for referral for investigations of oesophageal motility. Impedance measurement has now been incorporated into commercially available diagnostic manometry systems for more than a decade. This innovation, which offered the ability to record patterns of bolus transport without the need for simultaneous radiology, has for the most part failed to live up to expectations, offering few additional diagnostic insights. This review examines the potential pitfalls related to how impedance patterns are currently analysed and introduces and discusses the new concept of pressure-flow analysis integrating pressure and impedance measurements to derive new metrics linked to the pressures occurring within and around the bolus as it is being transported.