PTU-131 Oesophageal Thermal Sensitivity and Mucosal Integrity in Healthy Subjects. A Study using a Novel Peltier-Based Heating Device and Impedance

Abstract

Background: Investigation of esophageal sensitivity might help better improve phenotyping of patients with GERD, functional heartburn and non-obstructive dysphagia. Previous studies on esophageal thermal sensitivity used balloon techniques with warm circulating water. This method lacks linear control of the heating ramp, has relative heat loss (due to thermal conduction) and provokes a slight mechanical stimulation by the distended balloon. Esophageal mucosal integrity is important in symptoms perception and can be studied in biopsies “in vitro” or using baseline impedance “in vivo”. We developed a catheter-based device incorporating a “thermal stimulator” using Peltier heating technology and a pair of impedance electrodes to assess mucosal contact and integrity. We aimed to investigate esophageal heat sensation/pain thresholds and their relationship with mucosal integrity in healthy human subjects. Methods: 21 healthy volunteers (age 25.6y (range 19 - 49) underwent thermal stimulation using an esophageal catheter with a 7 mm electronic Peltier heater, to deliver a ramp heating protocol up to 60 °C at 5 and 15 cm above LES. Symptoms were recorded by a computerized Visual Analogue Score (VAS) and the referred area of pain (pixels) was measured. The delivered temperature at Pain Detection Threshold (PDT), time to PDT was measured and the area under the heating curve (AUC) was calculated. Esophageal impedance was assessed over 10 minutes pre (basal), during and post heating in the distal and proximal esophagus (Figure). An Identical protocol was repeated after 2 weeks to assess reproducibility (Bland-Altman test). Results: Parameters of thermal sensitivity in normal subjects are presented in the table. Temperature at PDT showed a very low SD in the distal and proximal esophagus (53.7 ± 2.7 and 54.3 ±2.3 °C respectively) and Bland- Altman Tests showed good reproducibility (-0.1905 95% CI -1.4132 to 1.0327). There were no significant differences in thermal sensitivity parameters between distal and proximal esophagus (table). In the proximal esophagus but not in the distal esophagus, the referred area of pain was significantly correlated with temperature at PDT (r = 0.5781, P= 0.006). Due to the low inter-individual variability in thermal sensitivity between healthy subjects, we could not find a significant correlation between basal impedance and time to first perception or time to pain perception both in the proximal and distal esophagus. Conclusion: A novel Peltier-based thermal stimulator device can accurately and reproducibly determine esophageal thermal sensitivity. In healthy subjects we could not demonstrate a correlation between basal impedance and sensitivity to heating. Undergoing experiments are assessing this correlation in NERD patients with hypersensitivity to acid. (Table Presented).