RecruitingPhase 4Drug trialCompare the Effects of Nebulizer Versus Inhaler Based Therapy for COPD Using Long-acting BronchodilatorsThe purpose of this study is to compare the effectiveness of inhaled bronchodilators delivered via nebulizers vs. dry powder inhalers (DPIs) in symptomatic participants with Chronic Obstructive Pulmonary Disease (COPD) who have airflow obstruction (FEV1/FVC ≤ 70%) and show significant air trapping (RV ≥ 120% of predicted). The investigators hypothesize that, in patients with symptomatic COPD, therapy with a long-acting anti muscarinic agent/long-acting beta agonist (LAMA/LABA) combination administered by nebulizer will improve hyperinflation (increase in inspiratory capacity and reduction in residual volume) and reduce symptoms related to COPD to a greater extent than LAMA/LABA therapy given by a DPI. The study aims to demonstrate the following: 1. Compare the values of inspiratory capacity (IC) and residual volume (RV) in patients receiving LAMA/LABA by DPI with those receiving LAMA/LABA by nebulizer 2. Compare patient reported outcomes (COPD Assessment Test (CAT score), Baseline/Transition Dyspnea Index (BDI/TDI) and the St. George Respiratory Questionnaire (SGRQ) in symptomatic patients with COPD receiving LAMA/LABA by DPI with those receiving LAMA/LABA by nebulizer