Comparison of esophageal acid exposure at 1 cm and 6 cm above the squamocolumnar junction using the Bravo™ pH monitoring system

Abstract

The aim of this study was to assess the quantitative differences of acid exposure at 1 cm and 6 cm above the squamocolumnar junction (SCJ) using two radiotelemetry pH capsules affixed to the esophageal mucosa. Ten normal subjects and 10 endoscopy-negative gastroesophageal reflux disease (GERD) patients without hiatus hernia (ages 20-54, 12 male) were studied for a 24-h period using the Bravo pH monitoring system. pH capsules were placed 1 cm and 6 cm above the SCJ. Interpretable data for at least 14 h was obtained in 18 of the 20 subjects (9 normal, 9 GERD). Two failures occurred secondary to early capsule dislodgement. Median esophageal acid exposure was significantly increased at 1 cm above the SCJ compared to 6 cm above the SCJ during the total, upright and postprandial time periods in both normal and GERD subjects. During a 2 h postprandial period the esophageal acid exposure was 8-fold greater in GERD subjects and 5-fold greater in normal subjects 1 cm above the SCJ compared to 6 cm above the SCJ. Confident measurement of esophageal acid exposure at a fixed position 1 cm above the SCJ is feasible with the Bravo system. Acid exposure was significantly higher 1 cm above the SCJ compared to 6 cm above the SCJ in both GERD patients and controls. These findings suggest that measurement of acid exposure 1 cm above the SCJ may improve accuracy of pH monitoring by detecting acid reflux events confined to the distal esophagus.

The Value of High-Resolution Manometry in the Assessment of the Resting Characteristics of the Lower Esophageal Sphincter

“…This degree of variation in positioning the probe may lead to inconsistencies in pH measurements, given the gradient of acid exposure in the distal esophagus that has been documented in both patients with GERD 12 and in normal subjects. 13 This inconsistency in pH probe placement can affect clinical management by reporting false positive and false negative pH monitoring.…”

Impact of prolonged 48-h wireless capsule esophageal pH monitoring on diagnosis of gastroesophageal reflux disease and evaluation of the relationship between symptoms and reflux episodes

“…Subsequently, it was demonstrated that the Bravo system is capable of distinguish between GERD patients and controls with sensitivity of 84% and specificity of 85% (18) . Acid exposure is greater just above the squamocolumnar junction (22) , however, by convention, in catheter-based pHmetry the tip of the probe is positioned 5 cm above the LES to prevent migration of the pH sensor into stomach, due to esophageal shortening during swallows, which in turn could lead to record false episodes of acid reflux (8) . Bravo system monitors pH with a capsule attached to esophageal mucosa, therefore, in a fixed position in relation to LES, overcoming this limitation seen with catheter-based pHmetry (21) .…”

Wireless Capsule pH Monitoring: Does It Fulfil All Expectations?

“…It has been suggested that wireless pH monitoring performed at 1 cm instead of 6 cm above the SCJ could enhance sensitivity and specificity of wireless capsule pH monitoring compared to traditional pH monitoring [19]. However, a recent study by Bansal et al [20] has shown that wireless pH monitoring performed at 1 cm above the SCJ does not improve the sensitivity or specificity of wireless pH monitoring compared to monitoring performed at 6 cm above the SCJ.…”