Can eustachian tube ventilatory function impairment after oxygen diving be influenced by application of free radical scavenger vitamins C and E?

Objectives/hypothesis: To evaluate the influence of free radical scavenger vitamins C and E on eustachian tube ventilatory function changes related to oxygen dives.

Study Design: Prospective, randomized, double-blind, placebo-controlled study of middle ear impedance changes of oxygen divers being orally treated with free radical scavenger vitamins C and E.

Methods: Fifteen divers were allocated to two groups. Before diving on oxygen on consecutive days (days 1 and 2), divers in group 1 took a daily dose of 1 g ascorbic acid and 600 International Units d-alpha-tocopherol and divers in group 2 were given placebo. Before diving and 2 and 24 hours after diving on days 1 and 2, middle ear impedance was measured.

Results: Impedance decreased overnight after dive 1 (P =.04) but not after dive 2 (P =.31). No impedance differences were found between groups after the dive on day 1 (P =.83). Twenty-four hours after the dive on day 1 and after the dive on day 2, impedance values in both groups were different (P =.02 vs. P =.07), emphasizing slightly more negative pressures in the vitamin group.

Conclusion: Vitamins C and E did not reduce eustachian tube ventilatory function impairment overnight after the dive on day 1, suggesting no evidence of free radical-mediated toxicity affecting the eustachian tube or middle ear mucosa. Repetitive oxygen dives may cause tissue adaptation suggesting other than antioxidant defense mechanisms.