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Introduction: Combined esophageal pH-impedance monitoring allows detection of nearly all gastroesophageal reflux episodes, acid as well as nonacid. However, the role of nonacid reflux in the pathogenesis of symptoms is poorly known. The aim of this study was to evaluate the diagnostic yield of this technique in patients with suspected reflux symptoms while on or off PPI therapy., Patients and Methods: The recordings of 150 patients recruited at seven academic centers with symptoms possibly related to gastroesophageal reflux were analyzed. Reflux events were detected visually using impedance (Sandhill, CO) and then characterized by pHmetry as acid or nonacid reflux. The temporal relationship between symptoms and reflux episodes was analyzed: a symptom association probability (SAP) > or =95% was considered indicative of a positive association., Results: One hundred fifty patients were included, 102 women (mean age 52 +/- 14 yr, range 16-84). Among the 79 patients off PPI, five did not report any symptom during the recording period. A positive SAP was found in 41 of the 74 symptomatic patients (55.4%), including acid reflux in 23 (31.1%), nonacid reflux in three (4.1%), and acid and nonacid in 15 (20.3%). In the group of patients on PPI (N = 71, 46 women, mean age 51 +/- 15 yr), 11 were asymptomatic during the study, SAP was positive in 22 of the 60 symptomatic patients (36.7%), including acid reflux in three (5.0%), nonacid reflux in 10 (16.7%), and acid and nonacid in nine (15.0%). The symptoms most frequently associated with nonacid reflux were regurgitation and cough., Conclusion: Adding impedance to pH monitoring improves the diagnostic yield and allows better symptom analysis than pHmetry alone, mainly in patients on PPI therapy. The impact of this improved diagnostic value on gastroesophageal reflux disease management remains to be investigated by outcome studies.

Background: Impedance-pH monitoring is the most sensitive method for detection and characterization of gastro-oesophageal reflux episodes. Normal values from European subjects are lacking., Aim: To build a database of gastro-oesophageal reflux patterns from French and Belgian healthy subjects., Methods: Seventy-two healthy subjects (35 men, mean age 35 years, 18-72) underwent 24-h ambulatory impedance-pH studies. Gastro-oesophageal reflux episodes were detected using impedance and characterized by pH as acid, weakly acidic, or weakly alkaline. Analysis was performed visually and effects of age, gender and intra-individual reproducibility were evaluated., Results: The total number of gastro-oesophageal reflux episodes was 44 (25,58,75) of which 59% were acid, 28% were weakly acidic and 10% weakly alkaline. Half of gastro-oesophageal reflux episodes were mixed (liquid/gas) and 22% reached 15 cm above the lower oesophageal sphincter. The bolus clearance time was 11 s while acid was chemically cleared in 34 s. Male gender was associated with increased number and proximal extent of total and acid gastro-oesophageal reflux. Repeated studies in 27 subjects showed good reproducibility for number, acidity and air-liquid composition of reflux (Kendall's W-values = 0.72-0.85)., Conclusions: This study demonstrates good reproducibility of 24-h ambulatory impedance-pH studies and provides values of reflux patterns in healthy subjects for comparisons with European gastro-oesophageal reflux disease patients.