[abstract] IS EUSTACHIAN TUBE VENTILATORY FUNCTION (ETVF) IMPAIRMENT AFTER OXYGEN DIVING MEDIATED BY FREE RADICALS?

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[abstract] IS EUSTACHIAN TUBE VENTILATORY FUNCTION (ETVF) IMPAIRMENT AFTER OXYGEN DIVING MEDIATED BY FREE RADICALS?

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Title: [abstract] IS EUSTACHIAN TUBE VENTILATORY FUNCTION (ETVF) IMPAIRMENT AFTER OXYGEN DIVING MEDIATED BY FREE RADICALS?
Author: Mutzbauer, TS; Muelle, PHJ; Tetzlaff, K; Neubauer, B; Sigg, O
Abstract: BACKGROUND: Negative middle ear (ME) pressure has been observed to occur due to intermittent obstruction of the Eustachian tube (ET) and gradual middle ear gas absorption. It has been suggested that negative ME pressure that can be observed after oxygen diving might be attributed to oxygen toxicity affecting ET or ME mucosa. The purpose of this study was to examine the influence of vitamines C and E as free radical scavengers on ETVF impairment after oxygen dives. METHODS: In a double-blind placebo-controlled study, each of 15 divers took daily either 1 g of ascorbic acid combined with 600 IU of d-alpha-tocopherol or placebo at least 3 h before a dive with a pure oxygen rebreathing diving apparatus at average depths of 4 m for 30 min on 2 consecutive days. Before, 2 h and 24 h after the dives ME impedance was measured by tympanometry (pressure range of -400 to +200daPa; GSI 28 Auto Tymp; Grason-Stadler, Littleton, MA). ME impedance results were compared by Wilcoxon test statistics. group, predive, post1stdive, post1stnight, post2nddive, post2ndnight; vitamin, 20, 185, 0, 55, 45, max; n equals 7, 0, -5, -17.5, -10, -7.5, median; [daPa], -60, -10, -150, -60, -35, min; placebo, 60, 35, 20, 10, 30, max; n equals 8, 25, -25, -5, 0, -25, median; [daPa], -15, -40, -55, -180, -15, min; p-value, .827, .01678, .0733, .6408; RESULTS: A decrease in ME Impedance was observed overnight after the first (p equals .015) but not after the second dive (p equals .4746) in both groups. No differences were found between groups with respect to ME impedance after the first dive (p equals .827). After the first night and after the second dive ME impedance values in both groups were different (p equals .01678/p equals.0733), emphasizing even slightly more negative pressures in the vitamin group. CONCLUSIONS: Application of vitamins C and E did not reduce ETVF impairment that was observed in both groups of oxygen divers 24 h after the first dive, suggesting no evidence of free oxygen radical-mediated toxicity affecting the ET or ME mucosa during and after oxygen diving. A phenomenon of tissue adaptation to repetitive hyperbaric oxygen exposure might be considered suggesting other than antioxidant defense mechanisms.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org)
URI: http://archive.rubicon-foundation.org/5372
Date: 2000

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  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

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