Criteria for Bronchoscopic Thermal Vapour Ablation
Bronchoscopic thermal vapor ablation (BTVA) should only be performed in patients with upper lobe-predominant emphysema who meet specific functional, anatomical, and physiological criteria. Based on the most recent evidence, BTVA represents a viable endoscopic lung volume reduction technique for carefully selected patients 1.
Patient Selection Criteria
Essential Criteria:
- Upper lobe-predominant emphysema confirmed by HRCT 1, 2
- FEV1 between 20% and 45% of predicted 1, 3
- Residual volume (RV) >175% of predicted 1
- Carbon monoxide diffusing capacity (DLCO) ≥20% of predicted 1
- Substantial hyperinflation 3
- Post-pulmonary rehabilitation 6-minute walk distance >140 meters 3
- Heterogeneity index (tissue/air ratio of lower lobe/upper lobe from HRCT) ≥1.2 2
Imaging Requirements:
- HRCT must demonstrate:
- Clear upper lobe predominance of emphysema
- Target segments with highest emphysema index
- Highest heterogeneity index to untreated ipsilateral lung lobes 1
Contraindications:
- Active pulmonary infection
- Recent myocardial infarction (within 6 weeks) 4
- Severe hypercapnia
- Pulmonary hypertension
- Previous lung surgery or lung transplantation
- Active smoking
Procedural Considerations
Pre-procedure:
- Complete pulmonary rehabilitation before consideration 3
- Spirometric parameters must be checked 4
- Arterial blood gas measurement if severe COPD (FEV1 <40% predicted and/or SaO2 <93%) 4
- Prophylactic antibiotics for patients with asplenia, heart valve prosthesis, or history of endocarditis 4
- Bronchodilator premedication for asthmatic subjects 4
- Coagulation studies (platelet count, prothrombin time) if biopsy anticipated 4
Procedure:
- Performed under deep sedation or preferably general anesthesia 1
- Special software assists in identifying target segments with highest emphysema index 1
- BTVA catheter positioned with occlusion balloon to isolate target segment 1
- Heated water vapor delivered for predetermined time according to vapor dose 1
Post-procedure Monitoring
- Strict monitoring for localized inflammatory response (LIR) 1, 5
- Monitoring for respiratory adverse events, which typically peak between 2-4 weeks post-procedure 5
- Patients with more prominent respiratory symptoms in first 30 days often experience greater long-term benefits 5
Clinical Pearls and Caveats
- The localized inflammatory response is an expected part of the treatment mechanism, leading to fibrosis and volume reduction 5
- Respiratory adverse events requiring antibiotics or steroids occur in approximately 36% of patients within 30 days 5
- BTVA should be performed within clinical trials or comprehensive registries where commercially available, as data remains limited 1
- Unlike endobronchial valves, BTVA can be effective regardless of collateral ventilation status 1, 6
- Sequential treatment of the most diseased segments rather than entire lobes may provide better risk-benefit ratio 3
BTVA represents a targeted approach for emphysema treatment with demonstrated improvements in lung function, quality of life, and exercise capacity in properly selected patients, though careful monitoring for inflammatory complications is essential.