It is now over 20 years since the introduction of multichannel intraluminal impedance monitoring (MII) in the oesophagus. 1 Soon following, its application in children began in earnest with the widespread availability of paediatric catheters in 2002. MII detects oesophageal bolus movement by measurement of changes in electrical resistance and is used for assessment of reflux in tandem with pH monitoring (MII-pH). MII-pH heralded an advance in our ability to characterise reflux compared with the previous gold standard, pH monitoring alone. Advantages include the ability to detect nonacid and weakly acid reflux, distinguish between antegrade and retrograde bolus movements, differentiate liquid from gas reflux and assess proximal extent of the refluxate. In the intervening period, the translation of this more sophisticated and accurate measurement into improved patient outcomes has, however, not been as demonstrable as would have been hoped for.

The BSPGHAN position statement on MII-pH testing, published in the current issue of the journal, highlights the current state of the technology, practical advice for performance of investigations, as well as many issues and controversies that pertain to the use of the technology in the paediatric setting, and often equally to adult practice. 2 The position statement, including its recommendations for practice, was formulated by consensus within a seven-member working group following literature review, but systematic evaluation of the quality of evidence supporting the recommendations was not reported. This probably reflects the low quality and lack of availability of evidence underpinning many of the recommendations.