378 Resting Upper Esophageal Sphincter Pressure Is Elevated in Proton Pump Inhibitor-Refractory Chronic Cough Patients and May Be a Marker for Laryngeal Hypersensitivity

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INTRODUCTION: Chronic cough is difficult to treat when unresponsive to proton-pump inhibitor (PPI) and sinus therapy. In this setting it is presumed to be neurogenic in etiology. Despite the role of the upper esophageal sphincter (UES) as a barrier to laryngopharyngeal reflux disease, it has not been well characterized in chronic cough patients. We aim to assess UES tonicity in patients with PPI-refractory chronic cough and otherwise intact esophageal motor function. METHODS: Patients with a Chicago Classification diagnosis of normal esophageal motility on high-resolution esophageal manometry (HRM) on studies performed for the indication of chronic cough were retrospectively studied. All studies were performed at a GI motility lab at a tertiary care center from January 2013 to August 2018. Patients with prior cervical spinal surgery, foregut surgery, gastroparesis, severe pulmonary disease or manometric hiatal hernia were excluded. All HRM were performed with a solid-state assembly with a 4.2 mm outer diameter catheter. Upper esophageal resting pressure and residual pressure (mmHg) were recorded from HRM studies and compared to a control group of patients with normal esophageal motility on studies performed for an indication of non-cardiac chest pain. Available pH-metry tests in chronic cough patients were also reviewed for acid exposure time. RESULTS: Fourteen patients with chronic cough (mean age 63 ± 25, 71% female) and twenty patients with non-cardiac chest pain (mean age 55 ± 14, 60% female) were included. Median resting UES pressure (mmHg) was higher in the chronic cough group (80) vs the chest pain group (50.8) with a p value of 0.004 (Figure 1). There was no difference in residual UES pressure (3.5 in chronic cough vs 3.15 in chest pain). A total of 12 pH studies were performed in chronic cough patients; 9 of these were on PPI. Median distal acid exposure time % was 1.35 [IQR 0.5-6]. CONCLUSION: UES hypertonicity found in PPI-refractory chronic cough patients may be a marker of laryngeal hypersensitivity. A second possibility is that primary UES dysfunction is the cause of cough in this subgroup.