Automatic online numerical analysis of prolonged recording of gastro-oesophageal acid reflux

An automatic numerical amplitude analyser was designed for use in conjunction with a measuring system for the recording of acid reflux at the distal end of the oesophagus. The analyser is described, and its use is discussed in the light of the results of stability and reliability studies carried out by way of 12 hin vitro andin vivo recordings. The apparatus has proved stable with an electrode drift of 0–0·2 pH units over 12 h. The analyser permits calculation of the temporal distribution of the pH values within various preselected intervals, expressed as percentages of the total time of recording. The accuracy of the analysis was tested on a simulated pH curve, and, within the frequency range 0·1–5 Hz, deviation was less than 1% for all analytical areas. By repeated analyses of the samein vivo studies, the coefficient of variation was calculated at 0·0001–0·10.