Development of a canine model of pulmonary emphysema and imaging of the emphysematous lung with infrared thoracoscopy

Background: The surgeon must use the results of preoperative computed tomography findings and scintigraphic studies to make a subjective decision during lung volume reduction surgery with regard to the best incision line. Objectives: Our Purpose was to develop an objective and real-time method of detecting areas of pulmonary emphysema by using infrared thoracoscopy. Methods: Pulmonary emphysema was developed in various lobes of the lung in the dog by injecting porcine pancreatic elastase through the bronchi. One month after the injection, chest computed tomography and lung biopsy were performed. Infrared thoracoscopic study was then performed to reveal the presence of the emphysematous lung tissue. Simultaneously, indocyanine green was injected intravenously, and the time taken for each type of lung tissue to stain blue was measured. Results: Chest computed tomography and histologic examinations revealed pulmonary emphysema-like areas in the porcine pancreatic elastase-injected lung. The computed tomography numbers of the porcine pancreatic elastase-injected lung tissue, normal lung tissue, and the tracheal lumen were -868.8+/-18.6, -752.2+/-32.5, and -1013+/-27.1, respectively. There were significant differences between the porcine pancreatic elastase-injected lung and the normal lung (P<.0001). The time for staining to begin was 10.7±4.8 seconds for normal lung tissue and 25.8±9.4 seconds for the emphysematous tissue; the onset of staining emphysematous lung tissue was significantly delayed (P=.003). Conclusions: We developed a successful canine model of pulmonary emphysema by injecting porcine pancreatic elastase. Infrared thoracoscopic examination revealed that the staining of emphysematous lung using indocyanine green injection was significantly greater than of normal lung.