Hyperbaric Oxygen Therapy for Acute Acoustic Trauma: Blast versus Noise-Induced Hearing Loss.

BACKGROUND

Blast injuries impair hearing through several mechanisms that are distinct from other causes of acute acoustic trauma (AAT).

OBJECTIVES

To compare blast injured patients to those exposed to noise alone in their auditory response to hyperbaric oxygen (HBO) therapy with oral steroids.

METHODS

Adult patients with evidence of a previously undocumented ≥ 30 dB pure-tone threshold within 30 days of AAT were treated with a combination of one 2.5 atm HBO therapy session for 90 minutes daily with oral prednisone. Exposure was classified by history as blast (for explosion-induced AAT) or noise. The change in high pure tone average (HPTA) was the primary outcome.

RESULTS

Of 598 ears (387 patients) included in the final analysis, 259 were exposed to blast and 339 to noise. Before treatment, the blast injured patients had significantly more abnormal findings on otoscopy (87% vs. 95%, P = 0.003), higher pure-tone average (18 ± 11 dB vs 12 ± 9 dB; P < 0.001), and higher speech reception thresholds (16 ± 14 dB vs 10 ± 8 dB, P < 0.001). Following treatment, these patients exhibited a significantly smaller improvement in HPTA (6 ± 17 dB vs 10 ± 14 dB P = 0.022) with pure tone thresholds remaining significantly worse across all frequencies in the blast exposed group (mean difference ranging from 3.2 to 6.8 dB, all P < 0.05).

CONCLUSIONS

Blast injuries result in unique auditory characteristics and responses to HBO therapy compared to other causes of AAT.