This allows the nitrogen solution to escape back into a gas without forming dangerous bubbles. This causes a delayed reaction in the formation of bubbles. An aural barotrauma, or ruptured eardrum, is caused by unequal pressure in the ear. If a diver cannot perform this activity successfully, then the greater pressure on the outside of the eardrum will cause the membrane to rupture. A diver presenting with this injury should be referred to medical aid to avoid complications leading to potential deafness.
First aid is to cover the ear with a pad, and discourage the application of eardrops or earplugs.
Discourage the casualty from attempting to perform the valsava manoeuvre. When a diver descends to a given depth, pressure on the body increases. When the diver ascends, the volume of air increases or expands. If the diver ascends rapidly, and doesn't compensate for this expansion by breathing out during surfacing, the expansion of the air exceeds the capacity of the lungs, and causes a rupture of the membrane. In extreme cases there may be evidence of red, frothy sputum, and associated back pain.