Proton pump inhibitors affect the size, relative acidity, and position of the acid pocket in gastroesophageal reflux patients, reported Dr. Wout O. Rohof and his colleagues.
"If one accepts that the acid pocket is still the source of the refluxate during PPI use, therapeutic strategies directly intervening with the acid pocket possibly may prove effective in preventing persistent symptoms on PPI," they wrote in the July issue of Clinical Gastroenterology and Hepatology News (doi.org/10.1016/j.cgh.2014.04.003-).
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While the total number of reflux episodes was similar for both PPI and non-PPI cohorts, the number of acid reflux episodes was lower on PPI.
"This insight is of great importance because in approximately 30% of patients PPI therapy fails to resolve symptoms, either partially or completely," they added.
Dr. Rohof of the Academic Medical Center in Amsterdam and his colleagues looked at 36 patients with gastroesophageal reflux disease (GERD) confirmed by the presence of esophagitis on endoscopy and/or impedance-pH-metry with an acid exposure of more than 4.5%, plus usual GERD symptoms.
Eighteen patients were on PPIs; the remainder had been off PPIs for at least 1 week prior to the study; eight PPI cohort patients used omeprazole, five used pantoprazole, and five used esomeprazole, with dosages varying from 20 mg (one patient), to 40 mg (eight patients), to 40 mg twice daily (nine patients).
All patients were fed a standardized meal of orange juice and pancakes; afterward, concurrent scintigraphy, high-resolution manometry, and pH-impedance recordings were acquired for 105 minutes.
At the study’s conclusion, the acid pocket – a floating pool of acid on top of ingested food, visualized on scintigraphy after patients were injected with a radioisotope – was aspirated for analysis of its pH level.
The authors found that overall, while the total number of reflux episodes was similar for both PPI and non-PPI cohorts (15 vs. 14; P = .81), "As expected, the number of acid reflux episodes was lower on PPI (4.5 vs. 2.0; P = .04)."
Only two patients in the entire cohort did not demonstrate an acid pocket on scintigraphy; both were taking PPIs.
Of the remaining patients, the size of the acid pocket was significantly less among PPI patients than their counterparts (10 cm2 vs. 15 cm2; P less than .01).
Moreover, when the acid pocket was aspirated at the conclusion of the study through the manometry catheter, the pH of the aspirated acid pocket fluid was significantly higher among PPI patients, compared with those not taking the drug (3.9 vs.0.9; P less than .001).
Finally, the investigators looked at the location of the acid pocket, which has also been shown to correlate with reflux episodes.
Their data showed that PPI patients were more likely to have the pocket located below the level of the diaphragm (60%), compared with patients not on PPI therapy (40%; P = .04).
This was especially important since pockets at this level correlated with only a 7% and 15% risk of acidic reflux events in PPI and non-PPI patients, respectively; in comparison, pockets in the hiatus and higher were associated with much greater rates of acidic reflux for both PPI and non-PPI patients, though the rates were lower among the former.
The authors disclosed no conflicts of interest or outside funding.