Figure 2.

 Simultaneous recordings of oesophageal pH using a conventional pH measurement system (CPHMS) with an antimony transnasal electrode (upper trace) and the Bravo catheter free system (CFS) (lower trace). (A) Several short reflux events observed on the upper trace do not appear on the lower trace. (B) Reflux events recorded by the Bravo catheter free system appear shorter for the time pH <4, and some reflux events reach the pH 4 threshold with the antimony transnasal electrode but not with the Bravo electrode.