Han Yang,1, Si Chen,2,3, Xiaoxuan Zheng,2,3, Ningxin Cui,1 Fangfang Xie,2,3 Huan Hou,2,3 Lin Ye,2,3 Felix J F Herth,4,5 Jiayuan Sun1– 3 1Department of Respiratory and Critical Care Medicine, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China; 2Department of Respiratory Endoscopy, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China; 3Shanghai Engineering Research Center of Respiratory Endoscopy, Shanghai, People’s Republic of China; 4Pneumology and Critical Care Medicine, Thoraxklinik, University of Heidelberg, Heidelberg, Germany; 5Translational Lung Research Center Heidelberg, German Center for Lung Research, Heidelberg, GermanyThese authors contributed equally to this workCorrespondence: Jiayuan Sun, Department of Respiratory Endoscopy, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200030, People’s Republic of China, Email xkyyjysun@163.com Felix J F Herth, Pneumology and Critical Care Medicine, Thoraxklinik, University of Heidelberg, Heidelberg, 69126, Germany, Email felix.herth@med.uni-heidelberg.dePurpose: Bronchoscopic thermal vapor ablation (BTVA) is a minimally invasive treatment for severe emphysema. However, the treatment doses are typically generated at the segmental level. In specific cases, treatment needs to be conducted at the subsegmental level, and the proportion can only be roughly allocated based on CT image review, potentially leading to dose mismatch. This retrospective exploratory study investigated the relationship between subsegmental dose accuracy (theoretical-to-actual matching) and clinical outcomes following BTVA.Methods: Patients who underwent BTVA at the Shanghai Chest Hospital between 2023 and 2024 were analyzed. Subsegmental theoretical doses (BroncQCT software) were compared to previously administered actual treatment doses. Dose matching was defined as: 1) segmental treatments were presumed matched (uniform vapor assumption), 2) subsegmental treatments required ≤ 10% deviation between actual and theoretical dose ratios (|Actual ratio - Theoretical ratio| × 100%). Patients with > 10% deviation or BroncQCT-identified nontarget subsegments were unmatched. Clinical parameters at 1, 3, 6, and 12 months after single treatment were compared.Results: Among 21 patients (15 matched, 6 unmatched), the mean changes in FEV1 for the overall cohort were +70mL at 1 month (n = 19, P = 0.018), +90mL at 3 months (n = 14, P = 0.056), and +130mL at 6 months (n = 8, P = 0.015). The matched group demonstrated superior median increases compared to unmatched patients (+150mL n = 9 vs +10mL n = 5; P = 0.012) at 3 months where between-group differences were maximal. Similar trends were observed at 1 month (median +110mL n = 14 vs 0mL n = 5; P = 0.044) and 6 months (median +150mL n = 5 vs +60mL n = 3; P = 0.036). Adverse events (including two late deaths in comorbid patients) were documented, though small sample sizes prevent definitive safety conclusions.Conclusion: This exploratory study found that subsegmental dose matching was associated with greater FEV1 changes after BTVA. These hypothesis-generating findings require prospective validation in a randomized controlled trial (NCT06152107).Keywords: bronchoscopic thermal vapor ablation, BTVA, chronic obstructive pulmonary disease, COPD, emphysema, bronchoscopic lung volume reduction, BLVR
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