Atelectasis has been defined by Van Allen and Lindskog1 as "an airless state of the lungs with collapse of the alveoli. No reference is implied to consolidation by replacement of air with exudate, transudate or other substance."
Atelectasis, other than that which is congenital, is due to obstruction to the passage of air, with subsequent absorption of the retained air and collapse of the alveoli. The extent of the collapse of the lung depends first on the location of the obstruction in the bronchial tree and secondly on the duration of the occlusion.2
Massive atelectasis due to the occlusion of a main bronchus has been described as having occurred during an asthmatic attack by various observers. The first recorded case of this type was that reported by Sante,3 in 1928. He described a case of massive collapse of the right lung which occurred during an asthmatic attack
TOWNSEND B. FRIEDMAN, CLEMENT J. MOLONY. ROLE OF ALLERGY IN ATELECTASIS IN CHILDREN. Am J Dis Child. 1939;58(2):237–249. doi:10.1001/archpedi.1939.01990080013001