Background:Obstructive sleep apnea/hypopnea syndrome (OSAHS) and laryngopharyngeal reflux (LPR) disease have a high comorbidity rate,but the potential causal relation between the two diseases remains unclear.Our objectives were to investigate the esophageal functional changes in OSAHS patients and determine whether OSAHS affects LPR by affecting esophageal functions.Methods:Thirty-six OSAHS patients and 10 healthy controls underwent 24-h double-probed combined esophageal multichannel intraluminal impedance and pH monitoring simultaneously with polysomnography.High-resolution impedance manometry was applied to obtain a detailed evaluation of pharyngeal and esophageal motility.Results:There were 13 OSAHS patients (36.1％) without LPR (OSAHS group) and 23 (63.9％) with both OSAHS and LPR (OSAHS and LPR group).Significant differences were found in the onset velocity of liquid swallows (OVL,P =0.029) and the percent relaxation of the lower esophageal sphincter (LES) during viscous swallows (P =0.049) between the OSAHS and control groups.The percent relaxation of LES during viscous swallows was found to be negatively correlated with upright distal acid percent time (P =0.016,R =-0.507),and OVL was found to be negatively correlated with recumbent distal acid percent time (P =0.006,R =-0.557) in the OSAHS and LPR group.Conclusions:OSAHS patients experience esophageal functional changes,and linear correlations were found between the changed esophageal functional parameters and reflux indicators,which might be the reason that LPR showed a high comorbidity with OSAHS and why the severity of the two diseases is correlated.