Effects of posture in hiatus hernia as studied by oesophageal pH measurement.

The use of postural restriction in the treatment of patients with hiatus hernia has been analysed using continuous oesophageal pH measurements. It appears that it is not effective in the prevention of reflux of acid. The percentage of the time during which oesophageal pH remains below 5 is not significantly different when comparison is made during periods of sitting and lying. The frequency of reflux episodes is actually greater in the sitting position, but the duration of each reflux episode is significantly shorter than when lying. It is suggested that the undoubted symptomatic benefit derived by hiatus hernia patients from adopting the sitting position is explained by improved clearance of regurgitated acid. This is a study into the effect of postural restriction on gastro-oesophageal reflux and into the rationale for its use in treatment. Fluoroscopy is a readily available and easy method for the examination of gastro-oesopha-geal reflux but the method lacks accuracy and does not lend itself easily to comparison between cases. In view of this, measurement using an in-dwelling pH electrode was chosen for this investi-A prolonged oesophageal pH recording, as suggested by Spencer (1969), was favoured as this establishes the pattern of gastro-oesophageal reflux in an individual patient. METHOD A dual pH glass electrode is used (Cambridge Instrument Company). In this a small glass electrode is connected to a pH meter by a co-axial wire. The reference half-cell is a salt-bridge (3 5 M potassium chloride solution) in the other lumen of the dual electrode connexion. A sintered glass plug near the distal end of the electrode retains the potassium chloride in the lumen of the tube though allowing diffusion at a rate of 7 isl/hr, thus establishing a closed electrical circuit. The output from the electrode is measured using a modified ammeter (Pye Unicam, model 292 pH meter). Permanent records are obtained with a pen-writing galvanometric recorder ('Inkwell' model). The response-time sensitivity lRequests for reprints to: Professor J. of this apparatus is 0-5 s, and a paper speed of 1 in/hr is used, as this speed is practical while still allowing satisfactory analysis of the tracing. The pH glass electrode was passed transnasally in the evening with little difficulty or discomfort to the patient and was positioned 5 cm above the cardiac sphincter. The exact level of this sphincter was previously datermined using manometric studies (Woodward, 1970) and simultaneous recordings of transmucosal potential change (Helm, Schlegel, …