In this procedure, the patient is placed in a 100% oxygen pressurised chamber to improve oxygenation in the blood. It is used to treat decompression sickness (‘the bends’) and embolism and has also been used to treat tinnitus for many years. The theory of administering oxygen is based on experimental evidence that noise exposure causes hypoxia (reduced oxygen) in the cochlea which can be reversed by HBOT protecting sensory hair cells.

A review of 22 studies from 1960 to 2007 showed no significant difference between HBOT and placebo as treatment for tinnitus.  However, a clinical trial conducted last year at the University of Helsinki found that HBOT significantly improved the recovery of hearing with reduced tinnitus persistence in patients who received HBOT when compared to a sham-pressurised chamber which had normal atmospheric oxygen. Both this study and earlier work found HBOT is most effective when used to treat patients with acute-onset tinnitus [[i]].