Snapshot A 29-year-old man presents to the emergency department with severe pleuritic chest pain. He tells the resident that he is worried he might have another collapsed lung. His temperature is 98.7°F (37.1°C), blood pressure is 118/78 mmHg, pulse is 119/min, respirations are 31/min, and oxygen saturation is 85% on room air. On examination, he appears cachectic. A chest radiograph is obtained. Introduction Clinical definition chronic obstructive pulmonary disease (COPD) is defined as persistent airflow limitation due to mixture of small airway disease and parenchymal destruction early classifications distinguished emphysema and chronic bronchitis no longer distinguished but helpful to separate for pathophysiologic understanding and clinical management emphysema is defined by alveolar wall destruction and dilation that presents in 2 forms centrilobular almost always due to smoking panlobular/panacinar rare and caused by alpha-1-antitrypsin deficiency misfolded alpha-1-antitrypsin (AAT), which normally inhibits elastase without AAT, elastase is over active and destroys elastic tissues can accumulate in hepatocytes and cause cirrhosis Epidemiology Demographics males > females 4th most common cause of death globally Risk factors tobacco use (most common) air pollution occupational exposure AAT deficiency ETIOLOGY Pathogenesis damage to airways distal to terminal bronchiole (i.e., acinus) abnormal dilation of airspaces and destruction of alveoli walls due to proteinases (i.e., elastase) decreased alveolar and capillary surface area, which decreases gas exchange Presentation Symptoms dyspnea mild cough fatigue hyperventilation Physical exam "pink puffers" non-cyanotic cachectic pursed-lip breathing accessory muscle use hypoxia barrel chest decreased breath sounds end-expiratory wheezing and/or prolonged expiration signs of cirrhosis if associated with AAT deficiency imaging Chest radiograph not required for routine diagnosis hyperinflation/flattened diaphragm bullae and/or blebs may have decreased lung markings Computed tomography not necessary for management but can determine classification of emphysema (centrilobular or panacinar) studies Pulmonary function tests (PFTs) best initial test decreased FEV1 / FVC (< 0.7) that is incompletely reversible obstructive pattern diagnostic FEV1 = forced expiratory volume FVC = forced vital capacity decreased % FEV1 used to categorize severity based on Global initiative for chronic Obstructive Lung Disease (GOLD) mild: > 80% moderate: 50-79% severe: 30-49% very severe: < 30% normal or decreased FVC increased total lung capacity (TLC) more than with chronic bronchitis decreased DLCO (vs. normal in chronic bronchitis) DLCO = diffusing capacity of the lungs for carbon monoxide Arterial blood gas (ABG) indicated for O2 saturation < 92%, altered mental status, or acute exacerbation hypoxemia decreased PO2 may cause increased hemoglobin/polycythemia acute or chronic respiratory acidosis increased PCO2 (hypercapnia) due to retention Differential Asthma distinguishing factor obstructive pattern on PFTs are reversible after administration of inhaled bronchodilator Bronchiectasis distinguishing factor computed tomography (CT) is gold standard for diagnosis large internal bronchial diameter, thickened bronchial wall, and altered airway geometry "tram-track" and "signet-ring" signs Interstitial lung disease (ILD) distinguishing factor restrictive lung pattern on PFTs Treatment First-line conservative smoking cessation greatest impact on mortality home O2 indicated if resting PaO2 < 55 mmHg or SaO2 <89% flu and pneumococcal vaccines pharmacological step-wise depending on GOLD classification of disease severity mild short-acting inhaled bronchodilators short-acting inhaled beta-agonist (e.g., albuterol) as needed short-acting inhaled anticholinergic (e.g., ipratropium) as needed most patients will present in more advanced stages moderate long-acting inhaled bronchodilator long-acting beta-agonist (e.g., salmeterol or formoterol) long-acting anticholinergic (e.g., tiotropium) can be used in combination severe inhaled corticosteroid (e.g., budesonide or fluticasone) + long-acting bronchodilator very severe triple therapy inhaled corticosteroid + long-acting anticholinergic + long-acting beta-agonist may require roflumilast phosphodiesterase (PDE)-4 inhibitor theophylline PDE inhibitor and adenosine receptor blocker indicated for severe and refractory disease low therapeutic index AAT deficiency IV pooled AAT Second-line lung resection or transplantation may be beneficial in severe cases refractory to medical management Complications Acute exacerbation Pneumothorax caused by rupture of bullae