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 hyper-baric oxygen (HBO) therapy with oral steroids. Methods: Adult patients with evidence of a previously un-documented ≥ 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 explo-sion-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. Be-fore 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 fre-quencies in the blast exposed group (mean difference rang-ing 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.