Pulmonary changes following extracorporeal membrane oxygenation: autopsy study of 23 cases

Extracorporeal membrane oxygenation (ECMO) has become an established mode of therapy in many centers for potentially fatal neonatal respiratory failure refractory to conventional therapy. We reviewed the findings of 23 autopsies of patients placed on ECMO therapy during the period from 1988 to 1992 at our institution in order to document the pulmonary histopathologic changes and to correlate such changes with the duration of treatment. Interstitial and intra-alveolar hemorrhages, as well as hyaline membrane formation, were the most common findings during the first few days of therapy. Reactive epithelial hyperplasia (bronchial and type II pneumocytes), squamous metaplasia, and smooth muscle hyperplasia were observed as early as 2 to 3 days after initiation of ECMO therapy. Interstitial fibrosis was noted only after 7 days of ECMO therapy. In three patients treated for 15, 19, and 21 days there was replacement of the terminal airways and alveoli by tall columnar and mucin-producing epithelium. Alveolar and bronchiolar calcifications were noted in seven of the 23 cases in this series. Pulmonary vascular changes were seen in association with persistent fetal circulation, meconium aspiration, and respiratory distress syndrome. These changes are most likely due to the compounded effect of ECMO and the underlying pulmonary insult.