Intranasal metered dose aerosolized surfactant reduces passive opening pressure of the eustachian tube: Comparison study in two animal models

Hypothesis: Intranasal metered dose aerosolized inhaler surfactant will reduce opening pressure of the eustachian tube in gerbils and mice. Background: Eustachian tube opening pressure necessary to allow ventilation of the middle ear must exceed the contractile force exerted by the tension on the curved surface of the eustachian tube. When the active function of opening the eustachian tube is inefficient, functional collapse of the tube persists, resulting in negative middle ear pressure. Such dysfunction is the primary cause of otitis media with effusion in children. Methods: Surfactant in a metered dose aerosolized intranasal delivery system was administered to 61 healthy Mongolian gerbils and 34 albino mice. In the first arm of the experiment, measurements of eustachian tube passive opening pressure were taken at baseline, after the delivery of propellant, and then at 5 and 10 minutes after surfactant administration. In the second arm of the experiment, the animals were divided into control, propellant, and experiment groups. At zero minutes, propellant was administered to the propellant group and intranasal surfactant was administered to the experiment group. Measurements of eustachian tube passive opening pressure were taken at 0, 5, and 10 minutes. Results: Surfactant administration in the gerbil reduced eustachian tube passive opening pressure from a basal measurement of 40.5 mm Hg to 32.5 mm Hg after 5 minutes and to 30.1 mm Hg after 10 minutes. In mice, eustachian tube passive opening pressure reduced from a basal level of 41.8 mm Hg to 31.3 mm Hg after 5 minutes and to 31.2 mm Hg after 10 minutes in the surfactant group. Propellant placebo resulted in no change from basal level in both animal models and in both arms of the experiment. Conclusion: Intranasal metered dose inhaler aerosolized surfactant is effective in reducing eustachian tube passive opening pressure.