Esophageal chemical clearance is impaired in gastro-esophageal reflux disease--a 24-h impedance-pH monitoring assessment.
BACKGROUND
Impedance-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).


METHODS
Blinded 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.


RESULTS
The 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
Impairment 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.
Fisiopatologia Digestiva, Nuovo Ospedale S. Agostino, Modena, Italy. marziofrazzoni@gmail.com
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Frazzoni
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Manta
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Mirante
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Conigliaro
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Frazzoni
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Melotti
D017097:Electric Impedance; D050782:Esophageal pH Monitoring; D004947:Esophagus / Q000503:physiopathology*; D005260:Female; D005764:Gastroesophageal Reflux / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D010528:Peristalsis / Q000502:physiology*; D012189:Retrospective Studies