Figure 1.

Characterization of acidity in the distal esophagus and proximal stomach under fasting conditions and in response to a large meal using high-resolution pH-metry in healthy subjects (8). The left panel shows the position of the 12-electrode catheter relative to that of the squamocolumnar junction (SCJ). The catheter was clipped to the SCJ with an endoclip using a loop tied between electrodes 4 and 5, 10.5 cm proximal to electrode 12, at the tip of the catheter. The right panel illustrates the pH contour plots (120 s duration each) of the high-resolution 12-electrode pH-meter (a) in the fasting state, showing marked intragastric acidity; (b) 3 min after the meal, showing intragastric buffering by food; (c) 17 min after the meal, showing emergence of the acid pocket at the esophagogastric junction; (d) 43.5 min after the meal, showing acid pocket enlargement; (e) 47.5 min after the meal, showing an acid reflux episode from the acid pocket (circled) despite simultaneous distal intragastric buffering; and (f) 73.5 min after the meal, simultaneously recording the proximal acid pocket and distal gastric acidity. This figure is from reference 8, and its use has been permitted by the publisher.