CRYOSURGERY OF RESPIRATORY STRUCTURES. II. CRYONECROSIS OF THE LUNG

This study was undertaken in dogs and monkeys to assess the sequelae of cryosurgery of the lung. In seven animals, a cryoprobe was repeatedly applied to the entire right middle lobe. In no instance was the probe inserted through the pleura into pulmonary parenchyma, but the pulmonary parenchyma was firmly compressed beneath the probe tip during freezing. This permitted through-and-through freezing of the entire right middle lobe and ensured complete cryonecrosis of the entire lobe. In three animals, a portion of the right lower lobe was also frozen by repeatedly applying the probe tip to the midportion of that lobe. All animals survived the procedures, and all resumed normal activity within 24 hours of operation. There were no pleural space complications except for the production of pleural adhesions. All lesions had the features of an acute hemorrhagic infarct, characterized by intense local hemorrhage and complete coagulation necrosis, typical of cryolesions. Subsequently, there was total collapse and fibrosis of underlying pulmonary tissue with areas of hemorrhagic necrosis, hemosiderin in macrocytes, focal calcification, and hyalinization. Serum lactic dehydrogenase values and leukocyte counts promptly increased after cryosurgery; however, all values returned to normal within 14 days, and no significant changes were noted thereafter. Thoracic roentgenograms showed changes consistent with consolidation of the right middle lobe, and by seven weeks, the only roentgeno-graphic evidence of the cryotreated middle lobe was a small density in the hilus. Histologically, this was a small mass of scarified tissue that sealed the bronchial stump and major vessels at the hilus and consisted of organized fibrosis.