Administration of free-radical scavengers (vitamins C and E) before oxygen diving did not improve eustachian tube ventilatory function.
- Appraised by: Mike Bennett, Dept. of Diving and Hyperbaric Medicine, Prince of Wales Hospital, Sydney; Sunday, 17 September 2000
- Clinical Scenario: A diver exposed to hyperbaric oxygen displayed negative middle ear pressures.
- Three-part Question: In divers using high inspired oxygen, does the administration of vitamins C and E, compared to placebo, prevent negative middle ear pressure after diving?
- Search Terms: Middle ear, eustachian tube
- The Study:
Double-blinded concealed randomised controlled trial with intention-to-treat. Fit volunteer naval divers
- Control group (N = 8; 8 analysed): Placebo medication at least three hours before diving (oxygen rebreather at 4m for 30 minutes average) on two consecutive days.
- Experimental group (N = 7; 7 analysed): 1g vitamin C and 600 IU of vitamin E at least three hours prior to diving (same exposure).
- The Evidence:
|Non-event outcomes||Time to outcome||Placebo group||Vitamin group||P-value|
|Middle ear impedance (1st dive)||24 hours||-5 daPa||-17.5 daPa||0.017|
|Middle ear impedance (2nd dive)||24 hours||-2.5 daPa||-7.5 daPa||0.64|
1. Administration of vitamins was associated with significantly worse eustachian tube function- this finding was the reverse of that hypothesised. 2. The putative action of vitamins was to reduce free-radical mediated mucosal damage that might explain the development of negative middle ear pressures after oxygen diving. 3. Report in abstract only
- Expiry date: June 2020
1. Mutzbauer T, Mueller P, Tetzlaff K et al. Is eustachian tube ventilatory function (ETVF) impairment after oxygen diving mediated by free radicals? Undersea and Hyperbaric Medicine 2000; 27(suppl):16.