Novel gel bolus to improve impedance-based measurements of esophageal cross-sectional area during primary peristalsis

Abstract

Introduction: Intraluminal esophageal impedance (ILEE) has the potential to measure esophageal luminal distension during swallow-induced peristalsis in the esophagus. A potential cause of inaccuracy in the ILEE measurement is the swallow-induced air in the bolus.

Aim: Compare a novel gel bolus to the current alternatives for the measurement of impedance-based luminal distension (cross-sectional area, CSA) during primary peristalsis.

Methods: 12 healthy subjects were studied using high-resolution impedance manometry (HRMZ) and concurrently performed intraluminal ultrasound (US) imaging of the esophagus. Three test bolus materials were used: 1) novel gel, 2) 0.5 N saline, and 3) commercially available Diversatek EFTV viscous. Testing was performed in the supine and Trendelenburg (-15°) positions. US imaging assessed air in the bolus and luminal CSA. The Nadir impedance values were correlated to the US measured CSA. A custom Matlab software was used to assess the bolus travel times and impedance-based luminal CSA.

Results: The novel gel bolus had the least amount of air in the bolus during its passage through the esophagus, as assessed by US image analysis. The novel gel bolus in the supine and Trendelenburg positions had the best linear fit between the US measured CSA and nadir impedance value (R² = 0.88 & R² = 0.90). The impedance-based calculation of the CSA correlated best with the US measured CSA with the use of the novel gel bolus.

Conclusion: We suggest the use of novel gel to assess distension along with contraction during routine clinical HRM testing.

Keywords: esophageal distension; esophageal impedance; intraluminal esophageal impedance; primary peristalsis; swallow gel.