Chronic hyperbaric oxygen therapy and the human nasal mucosa: increased thickness of epithelium basement membrane and moderate neutrophilic infiltration.

Objective: We aimed to identify potential morphologic changes induced in the nasal mucosa by hyperbaric oxygen (HBO) treatment. Study Design: Biopsies were obtained from two groups of 9 individuals: the first group had a diagnosis of tinnitus and was submitted to 15 sessions of 100 min-long HBO treatments, and the latter group consisted of healthy volunteers not submitted to HBO therapy. Methods: Small biopsies of the anterior portion of the lower nasal turbinate were collected with the help of a Hartmann forceps under direct visual inspection. The samples were processed for light microscopy and morphometric analysis. Inflammatory infiltration (neutrophils and lymphocytes) was evaluated by a semiquantitative method. Unpaired t test and Bernoulli distribution were applied to evaluate statistical differences between data from the two groups of samples. Results: Samples of the turbinate mucosa of the HBO-treated group showed a significant increase in the thickness of the epithelial basement membrane and a moderate enhancement in infiltrating neutrophils when compared with the samples from the control group. Conclusions: Chronic HBO treatment causes only minor changes in the architecture of the nasal mucosa that may represent the response of the respiratory tract to the increase in pressure and in oxygen content induced by this type of therapy.