ABSTRACT
Pulmonary hypoplasia refers to the abnormal development of an entire lung or both lungs, resulting in a diminutive and potentially dysfunctional gas exchange organ. This occurs most commonly as a consequence of extrinsic compression during gestational development, although primary hypoplasia does occur. A number of intrathoracic mass lesions may be responsible, however the most common are congenital diaphragmatic hernia and CCAM. Pulmonary aplasia results from developmental arrest during organogenesis sometime after the sixth gestational week, resulting in a reduction in the number of alveoli; this may be marked. The physiologic consequences of both derangements can be severe and include pulmonary hypertension, persistent fetal circulation and respiratory failure. Extraordinary measures of clinical support are frequently required32,46 including high-frequency oscillation, extracorporeal membrane oxygenation, and the use of inhaled nitric oxide.
