Wireless esophageal PH monitoring. Clinical evaluation of a new technique

Sammanfattning: Esophageal pH monitoring is important in the clinical management of patients with symptoms suggestive of gastroesophageal reflux disease (GERD), and in research aiming to clarify the mechanisms involved in the development of GERD complications. Catheter-based techniques for pH recording are uncomfortable, not well tolerated by all patients and cannot reliably measure acid exposure in the most distal esophagus the region most prone to reflux-induced complications. New wireless technique using a pH recording capsule attached to the esophageal mucosa was evaluated to provide a scientific basis for the clinical use of the technique, and to characterize acid exposure in the most distal esophagus. Healthy volunteers and symptomatic patients underwent wireless 48-h esophageal pH monitoring with endoscopic placement of pH recording capsules at the standard position 6 cm above the squamocolumnar junction (SCJ) and immediately above the SCJ. The patient's perceived experience of the wireless and catheter-based techniques were compared in a randomized cross-over trial. The wireless technique was feasible regarding capsule placement and recording of pH data via radiotelemetry, and there were no complications related to the procedure. Premature capsule detachment and signal interruption occurred but were uncommon at the standard electrode position. Endoscopic placement of the wireless capsule followed by 48-h pH recording was, compared to manometry and 24-h catheter-based monitoring, associated with less adverse symptoms, less interference with normal daily life and was preferred by a significant majority of symptomatic patients. Analysis of the diagnostic performance of the wireless pH test showed that the total percent time with esophageal pH<4 for the 48-h study period was the parameter that best distinguished GERD patients from healthy controls, and a cut-off level of 4% generated a test specificity of 93% and a sensitivity of 76% in patients with esophagitis and 42% in patients without mucosal injury. Simultaneous pH recording at the two monitoring levels showed that in healthy subjects, esophageal acid exposure immediately above the SCJ was characterized by shorter reflux episodes with a lower minimum pH, and that only 25% of distal reflux episodes were detected at the standard monitoring level. The standard pH electrode position significantly underestimated the acid exposure in the most distal esophagus in GERD patients. With a predefined specificity, pH monitoring just above the SCJ increased the sensitivity of the test from 78 to 97% in patients with esophagitis and from 47 to 73% in patients with no esophagitis. Placement of the pH electrode immediately above the SCJ may improve the diagnostic accuracy of wireless pH monitoring.