gastrointestinal disorders
Ambulatory pH Monitoring
Wireless pH Monitoring
Ambulatory esophageal pH monitoring can also be done using a wireless pH-sensing capsule that is attached to the distal esophagus. The device is endoscopically placed 5 cm above the lower esophageal sphincter and continuously monitors esophageal acid exposure (defined as pH < 4.0) for 48 to 72 hours. Similar to the probe-based test, patients record symptoms, meals, and sleep for the duration of the test, and excessive acid exposure and symptom-reflux correlation (symptom index or symptom association probability) are identified. However, because the capsule is a pure pH sensor, only acid reflux is detected. The capsule usually falls off within a week of placement and is spontaneously passed in the stool. The capsule transmits data wirelessly while attached and does not need to be retrieved. 