Chronic Obstructive Pulmonary Disease (COPD)

A common, preventable, and treatable disease characterized by persistent respiratory symptoms and airflow limitation that is not fully reversible, caused by significant exposure to noxious particles or gases (most often cigarette smoke) and driven by an abnormal chronic inflammatory response of the airways and lungs.

• The Washington Manual of Medical Therapeutics (p. definition section): "COPD is defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) as a mostly preventable and treatable disorder characterized by an expiratory airflow limitation that is not fully reversible. Exposure to noxious particles and gases..." - Washington Manual of Medical Therapeutics
• Fishman's Pulmonary Diseases and Disorders: "COPD is a heterogeneous disease characterized by persistent respiratory symptoms and airflow limitation due to airway and alveolar abnormalities. The causative agent is usually significant exposure to noxious particles or gases." - Fishman's Pulmonary Diseases and Disorders
• Katzung's Basic and Clinical Pharmacology: "COPD resembles asthma in that it is also characterized by airflow limitation, although the obstruction of COPD is not fully reversible with treatment. The airflow limitation of COPD... reflects an abnormal inflammatory response of the lung to noxious [particles/gases]." - Katzung's Basic and Clinical Pharmacology, 16th Ed.
• Symptom to Diagnosis: An Evidence-Based Guide: "COPD is defined in the WHO/NHLBI Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease (GOLD) as a 'disease state characterized by airflow limitation that is not fully reversible.'" - Symptom to Diagnosis, 4th Ed.

Key features of the definition

1. Airflow limitation - usually progressive, and not fully reversible even with bronchodilators (this distinguishes it from asthma, which is more reversible).
2. Chronic inflammation - an abnormal inflammatory response in the airways, lung parenchyma, and pulmonary vasculature to inhaled noxious agents (chiefly cigarette smoke, but also occupational dusts/chemicals, biomass fuel smoke, and genetic factors like alpha-1 antitrypsin deficiency).
3. Structural components: chronic bronchitis (mucus hypersecretion, mucus gland hyperplasia, goblet cell metaplasia) and emphysema (destruction of alveolar septa), often coexisting in varying proportions.
4. Diagnosis requires spirometry: confirmed by a post-bronchodilator FEV1/FVC ratio < 0.70 showing persistent airflow obstruction.
5. Clinically: presents with chronic productive cough, dyspnea, and wheeze developing over years, with risk of acute exacerbations.