PSEUDOREFLUX

Abstract

Purpose: Pseudoreflux is believed to be caused by drying of proximal placed pH electrodes during recumbency due to decreased saliva production and limited swallowing. As the electrode dries, the signal decays resulting in the classic pattern of a gradual decline in pH. This decrease in pH, if not identified as an artifact and excluded, will be read as a reflux episode, and potentially induce over diagnosis. The aim of this study is to identify the frequency of pseudoreflux, and evaluate its effect on interpretation of 24-hour esophageal pH studies. Methods: 200 consecutive dual electrode pH studies (135 females, 65 males; mean age = 50 years; range: 16 – 88) performed in our lab between July 2002 and February 2003 were analyzed for percent time pH <4 at the distal (normal values: total <4.2%; upright <6.3%; recumbent <1.2%) and proximal (normal values: total <1%; upright <1.3%; recumbent = 0) sites. All tracings were re-analyzed to identify episodes of pseudoreflux and acid reflux time recalculated with these episodes included and excluded. Results: 14 patients (7%) showed at least one typical episode of pseudoreflux during their studies. In all these patients, exclusion of the pseudoreflux episodes showed absent proximal recumbent esophageal acid exposure. When the pseudoreflux episodes were included in the analysis, all the patients (100%) had abnormal proximal recumbent esophageal acid exposure (mean: 5.2%; range: 0.4%-13.5%). Only 4 of these patients showed any abnormal esophageal acid exposure when pseudoreflux was excluded. Thus, not excluding pseudoreflux changed the overall diagnosis from a normal to an abnormal study in 72% (10/14) of these patients. There was also a significant difference in recumbent (p = 0.0001) and total (p = 0.0001) proximal esophageal acid exposure when including or excluding the pseudoreflux episodes. Conclusions: Pseudoreflux is seen on a regular basis during 24-hour esophageal pH studies. Ignoring the need to exclude these artifacts will most often lead to over-diagnosing gastroesophageal reflux disease.