Persistent airflow limitation (FEV1:FVC < 0.70) that is progressive and not fully reversible
The new definition from the GOLD initiative avoids either chronic bronchitis (85%) and emphysema (15%); most patients have mixture of both
Although smoking is a major risk factor for developing<unk> , only 15% of smokers actually develop<unk> 
Characterized by a combination of parenchymal destruction and small airway disease with failure of gas exchange
Acute<unk> s due to increased V/Q mismatch, not expiratory airflow limitation
Relative chronic hypoxia present in many
Chronic hypoxia can induce pulmonary hypertension, polycythemia and cor pulmonale
The new definition from the GOLD initiative avoids either chronic bronchitis (85%) and emphysema (15%); most patients have mixture of both
Chronic hypoxia can induce pulmonary hypertension, polycythemia and cor pulmonale
Infection (75%)
50% viral, 50% bacterial
Cold weather and environmental pollution
Beta-blockers
Opioids
Sedative/Hypnotic agents
Pneumothorax
PE
Congestive heart failure
Trauma (rib fractures, pulmonary contusion)
Bronchiectasis
Tuberculosis
Sarcoidosis
Lobar atelectasis (mucous plugging)
Noncompliance with prescription
50% viral, 50% bacterial
Recent hospitalization (>2 days within previous 3 months)
Frequent antibiotic treatment (>4 courses within past year)
Severe underlying<unk>  (FEV1 < 50% predicted)
Previous isolation of pseudomonas
COPD exacerbation
Pulmonary
Acute asthma exacerbation
Airway obstruction
Acute asthma exacerbation 
Anaphylaxis
Aspiration pneumonia and pneumonitis
Angioedema