Pulmonary EmphysemaEmphysemaPneumonectomyBronchoscopesalpha 1-Antitrypsin DeficiencySubcutaneous EmphysemaTotal Lung CapacityRespiratory Function TestsForced Expiratory VolumeMediastinal EmphysemaBronchoscopyPulmonary Disease, Chronic ObstructiveLungExercise ToleranceTomography, X-Ray ComputedSeverity of Illness IndexPancreatic ElastaseSmokeSmokingMatrix Metalloproteinase 12alpha 1-AntitrypsinPulmonary AlveoliLung Volume MeasurementsHeliumPulmonary Diffusing CapacityResidual VolumeVital Capacity