The pneumothorax was drained, but following a further pneumothorax on the left, the infant died. At 25 weeks, the lungs have not yet formed alveoli, the airways end in terminal sacs. Two fetal rabbit lungs showing the effects before and after giving artificial surfactant. The effect of surfactant treatment is to make the lungs function as if they were about a week more mature than the age of the infant. PerinatalPic7 Hyaline membrane disease Lung maturation is retarded by oligohydramnios, as might ocurr after premature rupture of the membranes.
Maturation is enhanced by stress, and by treatment of the mother prentally with dexamethasone.
Lungs which have insufficient surfactant are damaged by high ventilation pressures and by oxygen toxicity, and the necrotic epithelial lining and exudate forms the pink hyaline membrane seen in the micrograph. PerinatalPic8 Pulmonary interstitial emphysema High ventilation pressures can also cause airspaces to rupture into the interstitium of the lung, causing pulmonary interstitial emphysema. If these interstitial collections in turn rupture into the thoracic cavity, the result is a pneumothorax. The baby did not breathe spontanteously at birth, and required resuscitation. After 12 hours the infant developed seizures and signs of cerebral hypoxia. At one week of age a magnetic resonance imaging scan of the brain showed loss of cortical definition in the occipital lobes.