Pulmonary Changes in Cardiopulmonary Bypass: Short-term Effects on Granular Pneumocytes

¹ Department of Pathology Research, St. Luke's Hospital, and Institute of Pathology, Case Western Reserve University, Cleveland
² Departments of Biomedical Engineering, Case Western Reserve University and the Department of Medicine, Veterans Administration Hospital, Cleveland

Focal atelectasis, penriarterial hemorrhage and peribronchial hemorrhage were seen in six dogs subjected to approximately two hours of closed-chest total cardiopulmonary bypass. During bypass, mean compliances decreased, while compliances in three sham-operated dogs increased. Counts of granular pneumocytes (type II cells) in routine light microscopic sections showed no consistent differences in the numbers of these cells in bypass and sham-operated dogs. This finding was supported by similar results in 1µ sections from one bypass and one sham-operated dog. However, in the 1µ sections, the number of inclusions per granular pneumocyte was reduced. Since these inclusions are generally believed to be surface-active material (surfactant), the loss of inclusions may be the earliest light microscopic evidence of alteration in surfactant.