Induced atelectasis of the middle ear and its clinical behavior.

Atelectatic ears are often treated with ventilating tubes for long periods of time. However, a certain percentage of atelectatic ears and retraction pockets resolve spontaneously over time. In order to determine whether self-aeration had been achieved in atelectatic ears previously fitted with ventilating tubes, the tubes were sealed and the ears were then closely followed. Out of 37 such tests, atelectasis did not recur in 4 ears, allowing their ventilating tubes to be removed. In 33 tests atelectasis redeveloped within 1-2h after the ventilating tube was sealed, with ears reverting to the same degree and shape as the original atelectatic condition. The seals were then removed, resulting in resolution of atelectasis. These observations were enforced by previous observations of similar changes and suggest that the partial pressures of the blood gases may be an important factor in controlling the level and possibly also the pathogenesis of atelectasis. The method of testing described also can be used in selected cases to determine whether or not a given atelectatic ear still requires a ventilating tube.