CHRONIC COUGH Patients with gastro-oesophageal reflux disease and cough have impaired laryngopharyngeal mechanosensitivity

Background: Laryngopharyngeal sensitivity (LPS) is important in preventing pulmonary aspiration and may be impaired by anaesthesia and stroke. It has been suggested that gastro-oesophageal reflux disease (GORD) may also impair LPS, although the underlying mechanism is unclear. The aim of this study was to compare LPS in patients with chronic cough and GORD with healthy subjects and to determine the effect of laryngopharyngeal infusions of both acid and normal saline on LPS. Methods: Fifteen patients with chronic cough and GORD and 10 healthy subjects without GORD underwent LPS testing using the fibreoptic endoscopic evaluation of swallowing with sensory testing (FEESST) technique. LPS, as measured by the lowest air pressure required to elicit the laryngeal adductor reflex (LAR), was determined both before and after laryngopharyngeal infusions of normal saline and 0.1 N hydrochloric acid performed on separate days. Results: The mean baseline LAR threshold of the patient group was significantly higher (9.5 mm Hg, range 6.0–10.0) than in normal subjects (3.68 mm Hg, range 2.5–5.0; p,0.01). Retest thresholds were not significantly different. In normal subjects LAR thresholds were significantly raised after acid but not after saline infusion (p = 0.005). There were no complications associated with the procedure. Conclusions: Patients with cough and GORD have significantly reduced LPS to air stimuli compared with healthy subjects which could potentially result in an increased risk of aspiration. Exposure to small amounts of acid significantly impaired the sensory integrity of the laryngopharynx.