PWE-046 The development of human esophageal pain hypersensitivity is associated with anxiety and sympathetic nervous system activation: Abstract PWE-046 Figure 1

Abstract

Objective: Experimental acid infusion in the distal esophagus leads to secondary hyperalgesia in the proximal esophagus in most healthy subjects but 30% remain resistant. The factors that mediate differences in sensitization to acid are unclear and their study may help to understand risk factors for esophageal hypersensitivity in gastro-esophageal reflux disease. The aim is to determine the psychophysiological factors which predict the development of esophageal pain hypersensitivity (EPH) to acid infusion in healthy subjects using a validated model. Methods: Forty-eighgt healthy volunteers (mean age 29 y range 19-49 y, 33 male) underwent psychological profiling for, anxiety, depression and personality type. Baseline pain threshold (PT) to proximal esophageal electrical stimulation was measured using a visual analogue scales; before HCl acid infusion (0.15 mol L-1) in the distal esophagus for 30 min. This was followed by esophageal PT measurements in the proximal, unexposed esophagus at 30, 60 and 90 min. Parasympathetic (Cardiac Vagal Tone - CVT) and Sympathetic Nervous System (RR interval) responses were monitored throughout the study. Volunteers were classified as sensitizers if the proximal PT fell ≥6 mA after esophageal acidification. Results: Thirty-five subjects (73%) sensitized to acid, and 13 subjects (27%) did not sensitize. There was no difference in the age, sex or in personality domains between sensitizers and non-sensitizers (P > 0.05). Spielberg trait anxiety comparison indicated a trend, P = 0.08 for sensitizers to be more anxious than non sensitizers. At baseline there was no difference in CVT and RR interval between the two groups. During acid infusion the key difference in autonomic nerves system response was that in the sensitizers the RR interval was shorter in sensitisers than non sensitisers (sensitisers: Δ1.662 ± SE 48.9 vs non sensitisers: D66.13 ± SE 25.65. DRR interval difference 64.4 ms (SE ± 37.3) P = 0.002; see Fig. 1). Trait anxiety demonstrated a negative correlation with the RR interval r = - 0.35 (P = 0.04). Conclusion: Our results suggest that higher anxiety and SNS activation has a pro nociceptive effect on the (Figure presented) development of post-acid infusion esophageal sensitization. This may explain why individuals with anxiety or stress at the time of visceral injury or inflammation are more likely to go onto develop EPH.