Nitrous oxide and the middle ear.

A case of hearing deficit following nitrous oxide anaesthesia is reported. The mechanism and time course of nitrous oxide-induced intratympanic pressure changes are described and contrasted with the effects of non-nitrous oxide anaesthesia. The rate of increase is about 10 mm H20/min. The possibility that nitrous oxide may cause displacement of tympanic membrane grafts both outwards and inwards, or disrupt the reconstructed middle ear conducting mechanism, is raised again.