Hyaline membrane disease: a pathological study of 55 infants.

This study concerns the pathological changes found in the lungs of 55 newborn infants with hyaline membrane disease (HMD). The accepted appearances are a widespread resorption of air with collapse of many alveolar ducts and most alveoli, producing a severe atelectasis. The alveolar ducts and alveoli that remain open are distended and lined by a variable amount of homogeneous acidophilic material. There is intense vascular engorgement (Morison, 1952; Potter, 1953; Nesbitt, 1957). Numerous hypotheses have been proposed to explain the formation of the hyaline membranes: these include the aspiration of amniotic fluid (Farber and Sweet, 1931; Farber and Wilson, 1933; Blystad, Landing, and Smith, 1951; MacGregor, 1953), defect in pulmonary circulation with plasma transudate (Rudolph, Auld, Drorbaugh, Rudolph, Nadas, and Smith, 1959; Neligan, 1959), and a disturbance of alveolar surface tension (Avery and Mead, 1959; Klaus, Reiss, Tooley, Piel, and Clements, 1962). In this study an attempt has been made to determine the relation between the possible aetiological factors and the morphological findings. Particular attention has been paid to the degree of pulmonary maturation, the degree of pulmonary expansion or atelectasis, the extent of the hyaline membranes, the pulmonary lymphatics, the amount of aspirated amniotic fluid, the presence of alveolar oedema, the occurrence of pulmonary haemorrhages, and the relation of the hyaline membranes to the alveolar septa.