Pulmonary Disease, Chronic ObstructiveLung Diseases, ObstructiveForced Expiratory VolumeLung DiseasesLungSpirometryRespiratory Function TestsBronchodilator AgentsVital CapacityDyspneaPulmonary EmphysemaSmokingScopolamine DerivativesLung Diseases, InterstitialAdministration, InhalationOxygen Inhalation TherapySeverity of Illness IndexExercise ToleranceSputumEmphysemaCholinergic AntagonistsIpratropiumRespiratory MusclesAlbuterolSleep Apnea, ObstructiveAsthmaSmokeRespiratory InsufficiencyBronchitis, ChronicAdrenal Cortex HormonesBronchiQuality of LifeAdrenergic beta-2 Receptor AgonistsPulmonary MedicineRespiratory System AgentsTreatment OutcomeInspiratory CapacityCase-Control StudiesRespiratory MucosaRisk FactorsBronchitisRespiratory TherapyPneumoniaExpectorantsBronchoalveolar Lavage Fluidalpha 1-Antitrypsin DeficiencyNebulizers and VaporizersProspective StudiesLung NeoplasmsPositive-Pressure RespirationLung Volume MeasurementsOxygenInhalationRespiration, ArtificialRespiratory MechanicsHypercapniaBlood Gas AnalysisBreathing ExercisesExercise TestChronic DiseaseHospitalizationAirway ObstructionTime FactorsWork of BreathingDisease ProgressionQuestionnairesTotal Lung CapacityRetrospective StudiesPulmonary Gas ExchangeHeliumBronchoscopyLung TransplantationExhalationComorbidityBronchiectasisNoninvasive VentilationMetered Dose InhalersDouble-Blind MethodCross-Sectional StudiesHome Care Services, Hospital-BasedRespiratory SystemAirway ResistancePrevalencePhosphodiesterase 4 InhibitorsPulmonary VentilationBiological MarkersExercise TherapyAcute DiseaseInflammationPulmonary FibrosisCohort StudiesMucusEthanolaminesRespirationCoughGlucocorticoidsAnti-Inflammatory AgentsDiaphragmCarbon DioxideRespiratory Tract Diseases