Pulmonary Disease, Chronic ObstructivePulmonary EmphysemaEmphysemaLung Diseases, ObstructiveForced Expiratory VolumeSpirometryRespiratory Function TestsBronchodilator AgentsVital CapacityDyspneaLungSmokingDisease ProgressionSubcutaneous EmphysemaScopolamine DerivativesOxygen Inhalation TherapyAdministration, InhalationSeverity of Illness IndexExercise ToleranceSputumCholinergic AntagonistsSmokeIpratropiumRespiratory MusclesAlbuterolSleep Apnea, ObstructiveBronchitis, Chronicalpha 1-Antitrypsin DeficiencyAdrenal Cortex HormonesAsthmaRespiratory InsufficiencyMediastinal EmphysemaQuality of LifeAdrenergic beta-2 Receptor AgonistsBronchiTreatment OutcomeRespiratory System AgentsLung DiseasesPulmonary MedicineInspiratory CapacityBronchitisCase-Control StudiesRisk FactorsExpectorantsRespiratory TherapyRespiratory MucosaNebulizers and VaporizersPneumoniaProspective StudiesTime FactorsInhalationLung Volume MeasurementsPositive-Pressure RespirationRespiratory MechanicsAirway ObstructionHeliumBronchoalveolar Lavage FluidBlood Gas AnalysisOxygenHypercapniaExercise TestBreathing ExercisesTotal Lung CapacityHospitalizationWork of BreathingQuestionnairesRespiration, ArtificialRetrospective StudiesComorbidityTomography, X-Ray ComputedChronic DiseaseBronchoscopyNoninvasive VentilationAirway ResistancePhosphodiesterase 4 InhibitorsHome Care Services, Hospital-BasedPulmonary Gas ExchangeDouble-Blind MethodMetered Dose InhalersDiaphragmCross-Sectional StudiesPrevalenceBiological MarkersExhalationalpha 1-AntitrypsinCohort StudiesPulmonary VentilationExercise TherapyResidual VolumeInflammationRespiratory SystemPneumonectomyMatrix Metalloproteinase 12Acute DiseaseFollow-Up StudiesEthanolaminesPrognosisAirway RemodelingBronchiectasisStatistics, Nonparametric