Esophageal chemical clearance is impaired in gastro‐esophageal reflux disease – a 24‐h impedance‐pH monitoring assessment

AbstractBackgroundImpedance‐pH monitoring allows assessment of retrograde and antegrade intra‐esophageal movement of fluids and gas. Reflux is followed by volume clearance and chemical clearance, elicited by secondary and swallow‐induced peristalsis, respectively. We aimed to assess whether chemical clearance is impaired in gastro‐esophageal reflux disease (GERD).MethodsBlinded retrospective review of impedance‐pH tracings from patients with erosive reflux disease (ERD) and non‐erosive reflux disease (NERD), and from proton pump inhibitor (PPI)‐refractory patients before and after laparoscopic fundoplication. The number of refluxes followed within 30 s by swallow‐induced peristaltic waves was divided by the number of total refluxes to obtain a parameter representing chemical clearance namely the postreflux swallow‐induced peristaltic wave (PSPW) index.Key ResultsThe PSPW index was significantly lower in 31 ERD (15%) and in 44 NERD (33%) off‐PPI patients than in 30 controls (75%), as well as in 18 ERD (16%) and in 48 NERD (31%) on‐PPI patients than in 26 on‐PPI functional heartburn (FH) cases (67%) (P < 0.05 for all comparisons). In 29 PPI‐refractory patients, the median PSPW index was unaltered by otherwise effective antireflux surgery (20% postoperatively, 21% preoperatively). The overall sensitivity, specificity, positive, and negative predictive values of the PSPW index in identifying GERD patients were 97%, 89%, 96%, and 93%.Conclusions & InferencesImpairment of chemical clearance is a primary pathophysiological mechanism specific to GERD: it is unaffected by medical/surgical therapy, is not found in FH, and is more pronounced in ERD than in NERD. Using the PSPW index could improve the diagnostic efficacy of impedance‐pH monitoring.