Correspondence / Digestive and Liver Disease 46 (2014) 1052–1054
Proton pump inhibitor (PPI) therapy transforms the vast majority of acid refluxes into weakly acidic refluxes. The main advantage of combined impedance-pH over pH-only monitoring is that assessment of refluxes is allowed during PPI therapy independent of pH. Given the limitations of the symptom-reflux association indexes, we have developed the post-reflux swallow-induced peristaltic wave (PSPW) index in order to obtain a quantitative parameter useful to elucidate the mechanisms of PPI resistance [2]. The PSPW index has 95% accuracy in diagnosing gastro-oesophageal reflux disease (GERD) and efficiently discriminates erosive reflux disease (ERD) from non-erosive reflux disease (NERD) and both from functional heartburn [2]. It is unaffected by PPI therapy or otherwise effective surgical therapy, a low value hence representing a permanent marker of GERD [2]. Conversely, the mean acid clearance time (MACT) is halved by PPI treatment [3] and similar values are found in ERD and NERD [4]. In our on-PPI study, neither the percentage oesophageal acid exposure time (EAET) nor the number of acid refluxes significantly differed among patients with refractory reflux esophagitis (RRE), healed reflux oesophagitis (HRE), or NERD [1]. Acid refluxes were no more than 15% of the total [1]. As expected, the MACT showed a significant correlation with the %EAET (rs 0.802, P = 0.001) and did not differ significantly among the three groups of patients (median 109, 45, and 81 s, respectively, P = 0.118), confirming the limited value of acid reflux parameters in evaluating PPI refractoriness. As far as manometric patterns are concerned, apart from the most extreme conditions such as scleroderma oesophagus and achalasia, the relationship between oesophageal contractility and transit is complex and far from perfect [5]. Even high-resolution manometry is currently deemed unfit for predicting bolus transit [5]. In our study [1], patients with scleroderma oesophagus and achalasia were excluded and ineffective oesophageal motility, currently defined at traditional manometry by at least 50% pressure waves
Proton pump inhibitor (PPI) therapy transforms the vast majority of acid refluxes into weakly acidic refluxes. The main advantage of combined impedance-pH over pH-only monitoring is that assessment of refluxes is allowed during PPI therapy independent of pH. Given the limitations of the symptom-reflux association indexes, we have developed the post-reflux swallow-induced peristaltic wave (PSPW) index in order to obtain a quantitative parameter useful to elucidate the mechanisms of PPI resistance [2]. The PSPW index has 95% accuracy in diagnosing gastro-oesophageal reflux disease (GERD) and efficiently discriminates erosive reflux disease (ERD) from non-erosive reflux disease (NERD) and both from functional heartburn [2]. It is unaffected by PPI therapy or otherwise effective surgical therapy, a low value hence representing a permanent marker of GERD [2]. Conversely, the mean acid clearance time (MACT) is halved by PPI treatment [3] and similar values are found in ERD and NERD [4]. In our on-PPI study, neither the percentage oesophageal acid exposure time (EAET) nor the number of acid refluxes significantly differed among patients with refractory reflux esophagitis (RRE), healed reflux oesophagitis (HRE), or NERD [1]. Acid refluxes were no more than 15% of the total [1]. As expected, the MACT showed a significant correlation with the %EAET (rs 0.802, P = 0.001) and did not differ significantly among the three groups of patients (median 109, 45, and 81 s, respectively, P = 0.118), confirming the limited value of acid reflux parameters in evaluating PPI refractoriness. As far as manometric patterns are concerned, apart from the most extreme conditions such as scleroderma oesophagus and achalasia, the relationship between oesophageal contractility and transit is complex and far from perfect [5]. Even high-resolution manometry is currently deemed unfit for predicting bolus transit [5]. In our study [1], patients with scleroderma oesophagus and achalasia were excluded and ineffective oesophageal motility, currently defined at traditional manometry by at least 50% pressure waves
