Mutzbauer
Administration of free-radical scavengers (vitamins C and E) before oxygen diving did not improve eustachian tube ventilatory function.
Clinical Bottom Line:
1. Administration of vitamins C and E promoted rather than prevented negative ear pressures after oxygen diving.
2. The magnitude of the negative middle ear pressure was less after the second dive in both groups.
Citation/s: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.
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 |
Comments:
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
Appraised by:Mike Bennett, Dept. of Diving and Hyperbaric Medicine, Prince of Wales Hospital, Sydney; Sunday, 17 September 2000
Expiry date:June 2022
