Fluctuations of middle ear aeration in atelectatic ears

This is a prospective study of 27 eardrums which were found to be in an atelectatic condition before night sleep. On awakening in the morning, 10 (37.0%) of these ears were found to be inflated. The atelectasis as well as the presentation of spontaneous disappearance of the atelectasis were observed with the operating microscope. After awakening, the original atelectatic state reappeared within 65.7 min (on average). Spontaneous autoinflation of atelectatic ears cannot be explained by nocturnal CO2 diffusion into the middle ear, as CO2 would rediffuse within one order of time quicker than found-i.e. 6 min. The phenomenon emphasizes the fluctuating nature of atelectatic conditions.