A Pilot Study Evaluating Surfactant on Eustachian Tube Function in Divers

Background: Middle ear barotrauma (MEBT) is the most common medical complication in diving, aviation, and hyperbaric medicine. Eustachian tube dysfunction (ETD) quantifies the inability to open the eustachian tube (ET), risking MEBT. Surfactant administration improved ET function and efficaciously treated otitis media in a host of animal models. We performed a pilot study evaluating the efficacy of intranasal surfactant administration in reducing MEBT in repetitive diving. Methods: Eight divers participated in a subject-blinded, placebo-controlled, random order, multiarm (air and O )-repeated measures trial investigating the relative efficacy of intranasally administered surfactant, acetylcysteine and oxymetazoline, and orally administered pseudoephedrine versus saline-placebo in middle ear equilibration during repetitive, multiday diving. Subjects were tested with the Nine-Step Inflation/Deflation Tympa-nometry Test (NSI/DT) and sonotubometry (testing eustachian tube opening pressure [ETOP]) before and immediately after each dive. Results: Significant interaction effects were found for drug-by-test (F 8,668 = 4.05; p < 0.001) and the three-way interaction of drug-by-dive-by-test (F 16 668 = 2.47; p = 0.001) in sonotubometry testing. The ETOP revealed trends toward lowered (improved) values post- versus predive in all treatment arms, which was significant for oxymetazoline (p = 0.04). Only four of the eight subjects experienced any holds during diving. Statistical analysis of the NSI/DT data showed that none of the drug interventions resulted in improvements in ET function over that expected by chance. Conclusions: There is large intra- and intersubject variability in daily functioning of the ET as measured using the NSI/DT and sonotubomtery (ETOP). Sonotubometry engendered trends toward lowered (improved) values post- versus predive in all treatment arms. The repetitive dives did not result in a significant decrease in ET function as evidenced in the saline-placebo trials, circumventing an ability to detect superiority among the various treatment arms in our subject population. Additionally, since our study was underpowered to detect significant effects, we can only assert that various inhalational agents may improve middle ear ventilation in repetitive diving warranting further study. A larger subject population including subjects diagnosed with ET dysfunction may provide more statistical power to discern the benefit of inhaled agents as a useful prophylactic for preventing or reducing ET dysfunction during diving and/or hyperbaric/hypobaric pressure changes.