Supplementary Material for: Balloon Dilatation for Bronchoscope Delivery (BDBD) in a Swine Model: A Novel Technique for Ultra-Peripheral Lung Field Access and Accurate Biopsy

Introduction: In transbronchial biopsy of peripheral pulmonary lesions, the bronchoscope can reach only a limited depth due to the progressive narrowing of bronchi, which may reduce the diagnostic rate. This study examined the balloon dilatation for bronchoscope delivery (BDBD) technique, employing a novel balloon device to enhance bronchoscopy into the peripheral lung areas. Methods: Anaesthetised swine served as our primary model. Using computed tomography (CT) scans, we positioned virtual targets characterised by a positive bronchus sign and a diameter of 20 mm beneath the pleura. The bronchoscope was navigated along the pathways determined from the CT images. We performed balloon dilatation when bronchial narrowing obstructed progress to assess whether balloon dilatation would enable the bronchoscope to enter further into the periphery. Results: We established 21 virtual targets on the CT scans. An average of 12.1 branches were identified along the pathways on the CT scans; however, bronchoscopy without BDBD only allowed access to an average of 6.7 branches. Based on 72 balloon dilatations with 3.0-mm or 4.0-mm ultra-thin bronchoscopes, there was an average increased access of 3.43 and 5.14 branches per route, respectively, with no significant BDBD complications. The bronchoscope was able to reach the planned location along all pathways, and the mean final bronchoscopic endpoints were at an average distance of 14.7 mm from the pleura. Post-procedure CT confirmed biopsy accuracy. Conclusion: The BDBD technique can enhance access of a flexible bronchoscope into the peripheral lung fields, which could potentially allow more accurate transbronchial interventions for peripheral targets.引言：在肺外周病变经支气管镜活检术中，由于支气管进行性狭窄，支气管镜所能抵达的深度有限，这可能会降低诊断成功率。本研究针对支气管镜递送球囊扩张术（balloon dilatation for bronchoscope delivery, BDBD）展开探究，采用新型球囊装置以提升支气管镜进入肺外周区域的能力。 方法：本研究以麻醉猪为主要实验模型。通过计算机断层扫描（CT）影像，我们定位了具有阳性支气管征、距胸膜20mm的虚拟靶区。沿CT影像确定的通路导航支气管镜，当支气管狭窄阻碍镜身前进时，实施球囊扩张术，以评估球囊扩张是否可使支气管镜进一步深入肺外周区域。 结果：本研究在CT影像上共设定21个虚拟靶区。CT通路中平均可识别12.1个支气管分支，但未采用BDBD的支气管镜仅能平均抵达6.7个分支。针对72例使用3.0mm或4.0mm超细支气管镜的球囊扩张操作，每条通路平均可分别多抵达3.43和5.14个分支，且未出现与BDBD相关的显著并发症。所有通路中，支气管镜均能抵达预设位置，最终支气管镜操作的平均终点距胸膜约14.7mm。术后CT证实活检定位准确。 结论：BDBD技术可提升柔性支气管镜进入肺外周区域的能力，有望为外周靶区实现更精准的经支气管镜介入操作。