Key inclusion criteria:
- Severe emphysema: forced expiratory volume in 1 second (FEV1) ≤ 45% of predicted, TLC ≥ 100% of predicted, RV ≥ 150% of predicted
- Resting partial pressure of arterial carbon dioxide (Paco2) ≤ 60 mm Hg
- Resting partial pressure of arterial oxygen (Pao2) on room air ≥ 45 mm Hg
- Body mass index ≤ 31 kg/m2 for men, ≤ 32 kg/m2 for women
- Abstinence from smoking for at least six months
- Completion of pulmonary rehabilitation.