The Effect and Mechanism of Bronchoscopic Lung Volume Reduction by Endobronchial Valve in Korean Emphysema Patients

The prevalence of chronic obstructive pulmonary disease (COPD) is high (13.4%). In addition, COPD ranked 10th among the causes of death in Korea, and rose to 7th in 2008. Airflow limitation of COPD is caused by a mixture of small airway disease (obstructive bronchiolitis) and parenchyma destruction (emphysema). Bronchodilator and anti-inflammatory drugs, such as corticosteroids are effective to obstructive bronchiolitis. However, these drugs are not effective to emphysema.

Lung volume reduction was devised to remove hyperinflated lung, and to function remaining lung. Surgical lung volume reduction showed improving survival in selected emphysema patients. However, surgical lung volume reduction have bee performed rarely due to significant surgery-related mortality. In this regard, non-surgical lung volume reduction methods have been developed. Of them, bronchoscopic lung volume reduction by endobronchial one-way valve is mostly used method and showed lower early complications than surgery.

The bronchoscopic lung volume reduction using endobronchial valve was proved its efficacy and safety in several large clinical trials. Although there were procedure-related complications such as acute exacerbation of COPD, pneumonia, or hemoptysis, patients receiving endobronchial valves showed improved lung functions, exercise capacity and quality of life. The endobronchial valves got approved for Conformity to European (CE) Mark in Europe. In follow-up study for patients with endobronchial valves, their efficacy and survival of patients were dependent on atelectasis induced by valves. Collateral ventilation plays a key role in endobronchial valve-induced atelectasis. Therefore, assessment of collateral ventilation should be preceded before inserting endobronchial valve.

Computed tomography (CT) can visualize and characterize morphologic change of lung of patients with COPD. Lung perfusion and ventilation CT protocols were developed for quantitative assessment of COPD before and after medical treatment. The CT protocols were expected to select optimal patients for endobronchial valves and to evaluate their efficacy.

We attempt to evaluate efficacy of bronchoscopic lung volume reduction using lung perfusion and ventilation CT and other outcomes.

Inclusion criteria

• Age more than 40 and below 75
• Patients with smoking history and heterogenous emphysema on chest CT
• Advanced emphysema (FEV1/FVC <70%, FEV1 of 15-45%, TLC >100% and RV >150% predicted)
• Persistent symptoms refractory to treatment
• PaCO2 <50 mmHg and PaO2 >45 mmHg
• Body mass index (BMI) ≤31.1 kg/m2 (men) or ≤32.3 kg/m2 (women)
• 6-min walk distance >140 m after pulmonary rehabilitation

Exclusion criteria

• Diffusing capacity (DLco) <20% predicted
• Large bullae (exceed 5 cm)
• Alpha-1 antitrypsin deficiency
• History of thoracotomy
• Excessive sputum production (throughout the week)
• Severe pulmonary hypertension ( systolic pulmonary artery pressure ≥ 45mmHg, estimated from the peak velocity of a tricuspid regurgitant jet by doppler echocardiography)
• Acute respiratory infection
• Unstable angina, congestive heart failure, or acute myocardial infarction in 6 months