Pulmonary changes in congenital heart disease with Down's syndrome: their significance as a cause of postoperative respiratory failure.

Biopsy or necropsy specimens of lung from 28 patients with congenital heart disease and Down's syndrome were studied to establish the cause of the postoperative respiratory failure often seen in such cases. Changes in lungs seen after operation included interstitial emphysema and overdistension of peripheral air spaces, associated with hypoplastic alveoli and deficient elastic fibres in the alveolar wall. In specimens taken before operation alveolar hypoplasia was common but interstitial emphysema or overdistension of lower airways was found only rarely. Findings suggest that alveolar hypoplasia is characteristic of Down's syndrome and that distension of peripheral air spaces or interstitial emphysema was due to artificial inflation of the lung during surgery. The severity of the lesions correlated significantly with the duration of artificial respiration and with the severity of the respiratory failure. Hypoplastic lung tissue in patients with Down's syndrome appears to be more susceptible to mechanical stress, and this is likely to be the cause of postoperative respiratory failure.