Clinical and animal experiment studies to optimise the therapy for acute acoustic trauma.

Despite extensive educational measures and improved ear protection, acute acoustic trauma still represents a major problem for the young soldier in the Federal Armed Forces. The aim of the investigation was thus to establish the optimum therapeutic scheme that could be applied by the generally young and still inexperienced unit medical officer to patients who had suffered acute acoustic trauma and to demonstrate the therapeutic scheme in animal experiments. In the clinical section, ten studies conducted on 500 patients who had suffered acute acoustic trauma made it possible to show that the combination of low-molecular dextran, or low-molecular hydroxyethyl starch, and hyperbaric oxygenation produced the best therapeutic results in terms of hearing gain and tinnitus elimination by a statistically significant margin. The studies only included patients who showed no tendency towards spontaneous recovery, with strict exclusion criteria being applied. Through animal experiments, it was seen that hyperbaric oxygenation, in the manner in which we conducted it (100% oxygen at 2.5 bar), leads to an increase in the oxygen partial pressure in the perilymph of the guinea pig cochlea. This is due partly to diffusion and partly to the blood flow. In a further experimental approach using animals, it proved possible to show that 60 hours after damage by acoustic trauma and hyperbaric oxygenation, the number of inner ear sensory cells that had suffered morphological damage in the animal was lower than without the hyperbaric oxygenation by a statistically significant margin. At the same time, valuable information was gained on the epidemiology of acute acoustic trauma.