(A) conventional pH catheter (diameter 2.1 mm) used to monitor gastroesophageal reflux and intragastric pH, (B) multi-channel intraluminal impedance-pH catheter (diameter 2.1 mm) with impedance electrodes (4 mm in length) set in pairs at 2-cm intervals

(A) conventional pH catheter (diameter 2.1 mm) used to monitor gastroesophageal reflux and intragastric pH, (B) multi-channel intraluminal impedance-pH catheter (diameter 2.1 mm) with impedance electrodes (4 mm in length) set in pairs at 2-cm intervals

This allows for six impedance rings and one pH electrode in the esophagus and a second pH electrode in the stomach. The pH sensor is placed 5 cm above the LES and gastric pH at 10 cm below the LES.

LES: lower esophageal sphincter.

Courtesy of Radu Tutuian, MD and Donald O Castell, MD.

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