PURPOSE: Lung volume reduction surgery has been shown to benefit patients with severe emphysema by improving ventilation-perfusion mismatch. This study investigates the use of a sclerosing agent (sodium tetradecyl sulfate) to collapse excess lung tissue as a method of lung reduction in rats. The objective of this study is to determine if this agent is able to sclerose lung tissue, the extent of the sclerosis histologically, and the dose-response characteristics.
METHODS: Six normal rats were divided with two in each concentration group: 0.25%, 1%, and 3%. Rats were anesthetized with isoflurane and intubated. Each rat had the sclerosing agent injected into the right bronchus after exposure via right thoracotomy. The dwell time was 10 minutes. The right mainstem bronchus was ligated proximal to the injection site. The contralateral lung acted as a control.
RESULTS: Lung sclerosis developed rapidly with gross changes observable within minutes. Affected lung tissue became dusky, indurated, and consolidated. In the 3% concentration group, Hematoxylin&Eosin staining showed extensive hemorrhagic coagulative necrosis around the central airways with limited infiltration of inflammatory cells (75% of lung parenchyma involved). There was a sharp line of demarcation between injured and viable tissue with minimal airway sparing. In the 1% concentration group, 50% of the lung parenchyma was necrotic. In the 0.25% concentration group, injury was limited to 15% of lung tissue with patchy areas of necrosis around few airways. Epithelial lining was stripped in few large airways with substantially less alveolar necrosis. Elastin and trichrome staining showed preserved alveolar architecture and elastic connective tissue. The controls in all concentrations showed normal histology without necrosis.
CONCLUSION: This proof of concept experiment shows that endobronchial application of a sclerosing agent (sodium tetradecyl sulfate) is capable of obliterating lung parenchyma while preserving stromal architecture acutely. Localized application is feasible. The effects are seen in proportion to the concentration of the applied agent and distance from large airways.
CLINICAL IMPLICATIONS: This sclerosing agent has application in potential endobronchial volume reduction of emphysematous non-functional lung tissue.
DISCLOSURE: George Comas, No Financial Disclosure Information; No Product/Research Disclosure Information