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Pulmonology - Chronic Obstructive Pulmonary Disease - Fast Facts | NEJM Resident 360

Chronic obstructive pulmonary disease (COPD) is characterized by persistent expiratory airflow limitation due to destruction of lung parenchyma and decrease in elastic recoil. COPD is associated with chronic airway and parenchymal inflammation, and the resultant airway obstruction leads to air trapping and hyperinflation. The decline in lung function in COPD is generally progressive.

The most important risk factor for developing COPD is cigarette smoking. An estimated 25% of individuals with a history of cigarette smoking develop COPD. Globally, inhalation of biomass fuel emissions is another important etiologic agent. The principal pathophysiological features of COPD are shown in following image.

Pathophysiological Features of Airflow Obstruction in Chronic Obstructive Pulmonary Disease (COPD)

(Source: Outpatient Management of Severe COPD. N Engl J Med 2010.)

Assessment

Although spirometry is needed to make a diagnosis of COPD (see Investigations below), evaluation of symptoms, exacerbation history and risk, and physical examination findings provide important clues.

Presentation: COPD should be considered in anyone with the following symptoms:

• chronic cough

• chronic sputum production

• dyspnea

• history of exposure to risk factors

Patient symptoms can be rated using objective scales including:

• COPD Assessment Test (CAT): measures COPD symptoms (e.g., cough and shortness of breath) on a 0–40 scale, with a score of ≥10 indicating COPD symptoms that limit quality of life

• Modified Medical Research Council (mMRC) Dyspnea Scale: scores the degree of breathlessness from 0–4, with 4 representing the highest degree of exercise intolerance

Exacerbation history: In addition to symptoms, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommends using the ABCD assessment tool to document exacerbation history, determine patient level of risk, and guide subsequent pharmacologic management. The following figure describes the GOLD Refined ABCD Assessment Tool.

The Refined ABCD Assessment Tool

The numbers represent severity of airflow limitation (spirometric grades 1 to 4), and the letters (ABCD) represent symptom burden and risk of exacerbation.
(Reprinted with permission from the Global Strategy for Diagnosis, Management and Prevention of COPD 2020. © 2020 Global Initiative for Chronic Obstructive Lung Disease, all rights reserved.)

Prognostic factors: The BODE index (Body-mass index, airflow Obstruction, Dyspnea, and Exercise) is a simple, multidimensional grading system that incorporates the patient’s BMI, degree of airflow obstruction (FEV₁), subjective dyspnea symptoms (mMRC Dyspnea Scale), and exercise capacity (6-minute walking distance). The BODE index can be used to predict the risk of death from any cause and from respiratory causes in patients with COPD. The score ranges from 0–10; for every 1-point increase in the BODE index, the hazard ratio for all-cause mortality increases by 1.34 and for respiratory-related mortality by 1.62.

Physical exam: A number of physical exam findings can hint at an underlying diagnosis of COPD. These findings are a manifestation of airway obstruction, hyperinflation, and chronic hypoxemia. Patients may present with varying degrees of tachypnea, respiratory muscle use, and pursed-lip breathing.

• Hyperinflation: On examination, patients may appear cachectic from increased respiratory efforts. An increased anteroposterior-to-lateral diameter >0.9 is indicative of hyperinflation (barrel-shaped chest).

• Wheeze: On auscultation, diminished breath sounds may be heard due to decreased airflow. Auscultated wheeze has a high-positive-likelihood ratio for the diagnosis of COPD.

• Cyanosis: Examination of the hands may reveal cyanosis or nicotine staining.

For more information on the value of the physical exam in the diagnosis of airway obstruction, see this review. 

Investigations

Spirometry: A spirometry measurement of the ratio of postbronchodilator forced expiratory volume in 1 second [FEV ₁] to forced vital capacity (FEV**₁****/FVC) <0.7** is typically consistent with the diagnosis of COPD. GOLD classifies the severity of COPD based on the following spirometric measurements:

GOLD Classification of Airflow Limitation Severity

Category	Symptoms	Postbronchodilator FEV1
1	Mild	>80% of predicted
2	Moderate	50% to <80% of predicted
3	Severe	30% to <50% of predicted
4	Very severe	<30% of predicted

(Reference: Pocket Guide to COPD Diagnosis, Management, and Prevention, Global Initiative for Chronic Obstructive Lung Disease [GOLD] 2020.)

Initial Treatment

Smoking cessation: The importance of smoking cessation should be a key discussion with COPD patients because it has been associated with mortality reduction. See Smoking Cessation in the Ambulatory Care rotation guide.

Bronchodilators: First-line pharmacologic agents for treatment of COPD are inhaled bronchodilators (beta₂-agonist or anticholinergics) alone, in combination, or with the addition of inhaled glucocorticoids, depending on the patient’s symptoms. The use of bronchodilators and inhaled glucocorticoids is associated with a reduction in exacerbations and hospitalizations and improvement in FEV₁ decline. A growing body of evidence suggests that inhaled glucocorticoids are more effective in patients who have high blood eosinophil levels than in patient who do not.

Initial Pharmacologic Management of COPD Patients Based on Risk

Abbreviations: LAMA, long-acting muscarinic antagonists; LABA, long-acting beta₂-agonists; ICS, inhaled corticosteroids
(Source: Global Strategy for Diagnosis, Management and Prevention of COPD 2020. © 2020 Global Initiative for Chronic Obstructive Lung Disease, all rights reserved).

Supplemental oxygen: The use of supplemental oxygen is associated with reduced mortality but is indicated only if partial pressure of oxygen is ≤55 mm Hg or oxygen saturation is ≤88% while respiring ambient air. Patients with COPD and moderate desaturation (resting oxygen saturation of 89% to 93% or moderate exercise-induced desaturation) do not appear to benefit from supplemental oxygen.

Chronic macrolide therapy: In former smokers, chronic macrolide therapy with azithromycin has been shown to prevent COPD exacerbations and improve symptoms. This treatment can be considered in patients with persistent symptoms despite optimal inhaled therapy.

A simplified algorithm for the initial assessment and management of patients with COPD is provided below:

Algorithm for the Evaluation and Treatment of Persons with COPD or at Risk for COPD

(Source: Update on Clinical Aspects of Chronic Obstructive Pulmonary Disease. N Engl J Med 2019.)

COPD Exacerbation

COPD exacerbation is the acute change in baseline dyspnea, cough, and/or sputum beyond day-to-day variation that necessitates a change in therapy. Exacerbations are associated with reduced lung function and quality of life and increased morbidity and mortality. Exacerbations are typically associated with respiratory infections caused by viral and bacterial triggers, as described in the following table:

(Source: Infection in the Pathogenesis and Course of Chronic Obstructive Pulmonary Disease. N Engl J Med 2008.)

Treatment of COPD Exacerbations:

• Glucocorticoids are associated with a reduction in hospitalization and treatment failure in patients with COPD exacerbations.

• Antibiotics are also frequently prescribed for management of COPD exacerbations, especially those associated with increased purulence of sputum. Chronic macrolide therapy is associated with a reduction in COPD exacerbations.

See the GOLD Pocket Guide to COPD Diagnosis, Management, and Prevention, 2020 Report for a summary of the diagnosis and outpatient management of COPD.

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