Gastro-oesophageal refluxate: does it always have to be acid to be noxious?

Direct monitoring of bile acids using an electrode device has been described but not so far reported for long term monitoring. 5 Other techniques include continuous aspiration using a sump tube, 1 a sodium sensitive electrode (based on differences in sodium concentration between gastric and duodenal juice) 6 and a device measuring bilirubin concentrations spectrophotometrically (the Bilitec probe) as a proxy for bile acids. 7 Oesophageal aspiration studies in patients with an intact stomach have detected conjugated bile acids but rarely trypsin in oesophageal contents, with the highest concentrations occurring at night perhaps due to the diluting effects of saliva during the day; bile acids were generally detected in samples also containing refluxed acid.