Otitic barotrauma is defined as a non inflammatory reaction produced in the middle ear cleft when the air pressure within it is considerably lower than that of the surrounding atmosphere. Otitic barotrauma occurs while flying, during loss of height, but also in diving or in compression in a decompression chamber. The tympanic membrane retracts inwards with the relative decrease of pressure within the cleft. Vascular engorgement occurs throughout the cleft lining and is followed by oedema, ecchymosis and transudation of fluid, which may become sanguineous in severe cases. With sudden and intense pressure changes the tympanic membrane may rupture.