Comparative study of glass and antimony electrodes for continuous oesophageal pH monitoring.

Oesophageal pH monitoring data are influenced by numerous patient or technique related factors, or both. In this study, data recorded with glass microelectrodes or antimony electrodes, both with external cutaneous Ag/AgCl reference electrodes, connected to two different recording devices are compared. Pearson correlation coefficients regarding the reflux index (% of the investigation time with a pH less than 4) ranged from poor to excellent (0.55 to 1.00). Differences in data recorded with glass electrodes are not significantly dependent on the recording device (r:0.93 to 1.00 for the reflux index). The correlation between data simultaneously recorded with antimony electrodes is lower, although not significantly different for the reflux index (0.90). Correlation between data recorded with glass and antimony probes is rather poor (0.55 to 0.70). Therefore data recorded with antimony electrodes cannot be compared with those recorded with glass electrodes. The mean pH recorded with glass electrodes is lower than that with antimony probes.