Thermal Vapor Ablation for Lung Lesions in a Porcine Model.

BACKGROUND: Various methods for ablating peripheral lung lesions are being investigated; however, none have been successfully adapted for delivery via bronchoscopy. Vapor ablation is currently being used to bronchoscopically create lung volume reduction in emphysema patients. OBJECTIVES: In this study, an adaptation of that technology is evaluated for potential treatment of lung lesions in a live pig model. METHODS: In 5 anesthetized healthy pigs, vapor of varying energy levels was delivered bronchoscopically to 66 different lung subsegments with airway diameters of 2-5 mm. Two hours after treatment, a necropsy was performed and the ablated regions were assessed for ablation and tissue structure disruption. In 6 additional pigs, vapor was applied to 3 subsegments each. To evaluate the progression of the response to treatment, 2 were kept alive for 10 days, 2 for 21 days, and 2 for 32 days. RESULTS: Histopathological evaluation of the sections demonstrated that vapor is capable of creating a uniform field of necrosis following the subsegment anatomical boundary. The reliability of a uniform field is dependent on the level of energy delivered. An energy level that reliably creates a uniform field of necrosis was applied in chronic animals. The animals tolerated the procedure and posttreatment care. No cardiac arrhythmias, hemorrhage, stroke, respiratory distress, or pneumothorax occurred during or after treatment. CONCLUSIONS: Vapor ablation is a potentially safe and efficient means of ablating a targeted region of the lung. We hypothesize that vapor may be useful in treating lesions of the lung in humans.

Sequential vapour ablation of adjacent segments in canine lung.

INTRODUCTION: Vapour ablation is used to create lung volume reduction for emphysema patients to improve lung function and quality of life. This study characterises effects of vapour ablation treatment in lung segments within a lobe that are adjacent to lung segments previously treated with vapour in a healthy canine model. Because emphysema is a progressive disease, subsequent treatments could offer continued benefit to the patient. METHOD: Six healthy canines were treated with vapour at 8.5 cal/g in one upper lobe segment. After a 4-week healing period, the adjacent segment was treated. After a second 4-week healing period, necropsy was performed and the tissue inspected. Clinical effects were monitored during each healing period. RESULTS: Each treatment was well tolerated and no significant abnormalities were observed during the healing phases, including death, pneumothorax, or major decline in health status. Animal health, oxygenation changes, pathology, and airway changes were monitored during the study. Analysis of these end points showed no difference in changes after treatment 2 as compared to changes after treatment 1. CONCLUSION: In this model, there was no evidence of increased or different clinical observations after a second adjacent vapour ablation. It was not possible to differentiate between the clinical effects of treatment 1 and the clinical effects of treatment 2. These results support investigation of sequential adjacent segmental vapour treatments in humans.