Gastroesophageal reflux and eustachian tube dysfunction in an animal model.

Objective: To explore the possible relationship between gastroesophageal reflux and eustachian tube dysfunction in an animal model.

Study Design: Randomized trial.

Methods: Twenty Sprague-Dawley rats were randomly assigned into two groups, the control (phosphate-buffered saline, n = 10) and experimental (hydrochloric acid [HCl]/pepsin, n = 10) groups. All rats underwent an operation to implant a polyethylene tube into the posterior nasopharynx, through which phosphate-buffered solution or simulated gastric juice (0.5 mg/mL pepsin in 0.01 HCl) was infused at a rate of 0.1 mL/h for 2 0 minutes three times a day for 7 days. Passive opening pressure (POP), passive closing pressure (PCP), active clearance of positive pressure (ACPP) and active clearance of negative pressure (ACNP) were measured before catheter implantation, on postoperative day 5, and after days 1, 3, 5, and 7 of infusion. Mucociliary clearance time (MCCT) was measured after day 7 of infusion. Statistical analysis used a two-way analysis of variance (POP, PCP, ACPP, and ACNP) and Mann-Whitney rank sum test (MCCT).

Results: Significant increases in POP (P = .004), PCP (P <.001), ACPP (P <.001), ACNP (P <.001), and MCCT (P <.001) were demonstrated in the HCl/pepsin group compared with the control group. No significant difference was seen between preoperative and postoperative values.

Conclusions: Nasopharyngeal exposure to simulated gastric juice causes eustachian tube dysfunction in rats. Specifically, middle ear pressure regulation and mucociliary clearance of middle ear contents were disabled. These results support recent reports in the literature linking nasopharyngeal reflux to eustachian tube dysfunction and secondary development of otitis media.