[Changes and implications of esophageal function in patients with chronic cough induced by gastroesophageal reflux]

Objective: To explore the changes in the esophageal function and their association with the therapeutic outcome in patients with gastroesophageal reflux-induced chronic cough (GERC). Methods: One hundred thirty-five patients with definite GERC consecutively referred to our respiratory clinic were recruited into the study between January 2012 and August 2015.Cough was due to acid reflux in 81 patients and non-acid reflux in 54 patients, with the favorable response to the standard antireflux therapy in 88 patients and to the intensified antireflux treatment in 47 patients. The control groups included 26 patients with gastroesphageal reflux disease without cough and 22 healthy volunteers. All the subjects underwent an esophageal manometry from which the parameters were recorded, including the pressure, length and relaxation rate of lower esophageal sphincter, and the peristaltic contractive amplitude, wave velocity and contractive time of esophagus. The data were combined with the results of multi-channel intraluminal impedance combined with pH monitoring to analyze the changes of esophageal function in the patients with acid or non-acid GERC and their relation to the outcomes of antireflux therapy. Results: Compared with healthy volunteers, patients with GERC presented with a lower pressure [(11±5) mmHg vs (15±5) mmHg (1 mmHg=0.133 kPa), q=3.70, P=0.000], shorter overall length [(2.2±0.5) cm vs (3.0±1.0) cm, q=2.78, P=0.017] and similar relaxation rate of lower esophageal sphincter(q=1.14, P=0.258). Furthermore, they also showed a decrease in esophageal peristaltic contractive amplitude [(33±13) mmHg vs (45±11) mmHg, q=2.19, P=0.030] and wave velocity [(2.6±0.8) cm/s vs (3.4±0.6) cm/s, q=2.91, P=0.010] but an increase in esophageal contractive time of esophagus [(4.9±2.2) s vs (3.1±0.8) s, q=3.25, P=0.001] in addition to a linear negative correlation between esophageal peristaltic wave velocity and bolus clearance (r=-0.603, P=0.000). However, these parameters were not different between patients with GERC and gastroesophageal reflux disease without cough. The patients with GERC due to acid and non-acid reflux presented with a similar esophageal dysmotility but different variables reflecting the acidity of refluxates as indicated by multi-channel intraluminal impedance combined with pH monitoring. The esophageal peristaltic wave velocity was significantly lower in the patients with GERC responsive to the standard antireflux therapy than in those responsive to the intensified antireflux therapy [(2.2±0.6) cm/s vs (3.0±1.0) cm/s, t= 2.066, P= 0.041]. Conclusions: Esophageal dysfunction is present in patients with GERC. Its characteristics and severity are not associated with the types of gastroesophageal reflux inducing cough, but may predict the efficacy of medical antireflux therapy.