Chronic obstructive pulmonary disease (COPD) is common, preventable, and treatable disease, characterized by persistent respiratory symptoms (chronic cough, sputum production) and airflow limitation (dyspnea)1. COPD can cause loss of lung function over time as a result of poorly reversible airflow limitation. Cigarette smoking is the most common risk factor, accounting for 85% to 90% of cases of COPD.
COPD is a combination of chronic bronchitis and emphysema1. Chronic bronchitis is characterized by chronic inflammation and mucuous hypersecretion, which result in destruction of lung tissue and disruption of normal repair and defense mechanism, leading to small airway inflammation and fibrosis. All these ultimately result in a widespread destructive changes that trap air, worsen the airflow limitation, and cause COPD symptoms (dyspnea, chronic cough, sputum production).
Inhalation of noxious particles and gas, such as smoke, dust, particles, or chemicals can stimulate the activation of inflammatory cells and mediators (i.e. macrophages, CD8+ lymphocytes, TNF-α, etc.) in COPD. Other pathophysiological process includes the imbalance between proteases and anti-proteases in lungs due to the hereditary deficiency of the protective anti-proteases α1-antitrypsin (AAT). This genetic factor increases the risk of developing COPD prematurely.
Table 1 below shows the differences between COPD and asthma2:
Table 1Differences between COPD and Asthma2 |Favorite Table|Download (.pdf) Table 1 Differences between COPD and Asthma2
| ||COPD ||Asthma |
|Onset ||Mid-life ||Earlier in life (childhood) |
|Driven Inflammation ||Macrophages + Neutrophil ||Eosinophils + Mast cells |
|Smoking history ||Usually > 10 years ||Uncommon |
|Allergy ||Uncommon ||Common |
|Symptoms ||Certain trigger or worse certain time of day ||Slowly progressive |
|Reversed with SABA ||Very little (if any) ||Yes |
|Mainstay of therapy ||Bronchodilators ||Inhaled corticosteroid |
Notes: Because inflammation in asthma is driven by eosinophils and mast cells, not macrophages and neutrophil, glucocorticoids are much more effective in asthma, but not in COPD.
The following factors can serve as clinical suspicions of COPD, when other common reasons (i.e. heart disease, pneumonia) for shortness of breath and cough have been ruled out1:
40 years of age older
Persistent dyspnea, chronic cough or sputum production
Known exposure to risk factors (cigarette smoking)
After all other causes of dyspnea have been ruled out and the above criteria are met, patients undergo lung function testing with spirometry to confirm COPD. As mentioned in the "Asthma" section, spirometry measures the amount of air a person can exhale and the amount of time it takes to breathe out. A forced expiratory volume in one second/forced vital capacity (FEV1/FVC) of < 70% confirms diagnosis of COPD.
The goals of COPD assessment are to identify the severity of disease (airflow limitation) and determine the impact on ...