Pandolfino et al (Gut 2005;54:1687–92) and Bruley des Varannes et al (Gut 2005;54:1682–6) presented data from simultaneous pH monitoring by wireless Bravo and catheter mounted antimony electrode systems. Both studies demonstrated that the wireless system recorded significantly fewer reflux events; the effect on overall acid exposure was more limited. Further analysis revealed that events “missed” by the Bravo system were shorter and less acidic than those detected by both systems. The authors suggested that the different recording characteristics of the two systems explain the apparent “higher sensitivity” of the catheter pH system, including the lesser sampling rate of the Bravo system, and the systematic inaccuracy in catheter electrode calibration (not assessed by Bruley des Varannes et al).

Beyond these technical concerns, the significance of short “reflux events” is questionable because short drops to pH <4 can be caused by factors unrelated to gastro-oesophageal reflux: firstly, ingestion of …