Pulmonary structural changes in neonatal hyaline membrane disease treated with high pressure artificial respiration.

Fourteen babies with hyaline membrane disease were treated with artificial respiration using intermittent positive pressure. At present six children are in good health; four still show alterations on the chest radiograph. Eight babies died; in these, high pressures (50 cm. HO on the average) were used with high concentrations of oxygen (up to 100%). Severe pulmonary changes were found. The lungs were heavy and non-aerated. There was emphysema only in the child treated for six weeks. Bronchi and bronchioli showed a marked epithelial hyperplasia as well as squamous-cell metaplasia, whereas at other sites epithelial necrosis was apparent. The muscular layer was hypertrophic and mucous glands appeared hyperplastic. Hyaline membranes containing bilirubin pigment were found in six of the eight cases. The alveolar epithelium was extremely atypical. The interstitium showed a proliferation of fibroblasts which resulted in a pronounced interstitial fibrosis in the child treated for six weeks. It is suggested that this treatment may aggravate the pathological changes caused by the hyaline membrane disease itself. Therefore, artificial positive pressure respiration should be used only when other measures fail to help the infant during the period when spontaneous recovery is possible.