Introduction Percutaneous cryoablation has been adopted for small, malignant peripheral pulmonary lesions and has yielded favourable results as a less invasive local treatment. A transbronchial approach may reduce the risks of complications, such as pneumothorax and pleural haemorrhage. A fundamental animal experiment on transbronchial cryoablation was performed to examine its immediate safety and effectiveness.
Methods Experimental cryoablation was performed on swine lungs using a rigid cryoprobe, 2.4 mm in diameter. The probe was introduced from the right main bronchus into the distal bronchus via thoracotomy, perforated the end of the conducting bronchus and reached the lung parenchyma. The temperature of the cryoprobe tip reaches approximately −130°C during freezing and approximately 20°C during thawing. After three freeze-thaw cycles, the cryoprobe was removed.
Results No significant haemorrhage was bronchoscopically observed in the airways throughout the experiment. The chronological changes and spatial distribution of the temperature of the pulmonary tissue circumferential to the point of the cryoprobe were similar to those seen with transpleural cryoablation and the less than −20°C thermal zone seemed to be established within a radius of at least 12 mm. The central destruction zone of alveolar structures was histologically similar to the thermal zone, while the conducting bronchus structure and the accompanying pulmonary artery were not severely affected.
Conclusion Experimental transbronchial cryoablation with a rigid cryoprobe could effectively freeze and destroy peripheral lung alveoli without any significant immediate adverse effects. This may suggest the potential clinical application of transbronchial cryoablation for peripheral malignant lung lesions.
- transbronchial cryoablation
- lung cancer
- metastatic lung tumor
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Contributors MKo, HY, SN, MKa and MI designed the research. MKo, RH, KO, HY, SN and MI performed the research. MKo analysed the data and wrote the paper.
Funding This study funded by Japan Society for the Promotion of Science (Grant-in-aid for Scientific Research (C) # 17K1080) 2016 Tokai University School of Medicine grant-in.
Competing Interest None declared.
Patient consent Not required.
Ethics approval statement All experiments were conducted in accordance with protocols approved by the Animal Experimentation Committee of Tokai University and was performed in compliance with its Animal Experimental Guidelines.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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