Diagnosis and Staging

By the time many patients present for treatment, the diagnosis of COPD is apparent. In addition to symptoms of dyspnea, chronic productive cough, and functional limitations, patients can show physical findings of lung hyperexpansion

(increased lung span on percussion, increased thoracic AP diameter, and use of accessory muscles of respiration). Extra-thoracic signs include peripheral or central cyanosis, nail clubbing, and signs of increased central venous pressure or even right-sided heart failure. Box 18-3 presents the differential diagnosis and distinguishing features of COPD suggested by the GOLD guidelines. Any patient who develops

Box 18-3 Differential Diagnosis of COPD* (GOLD Guidelines)

COPD

Onset in midlife

Symptoms slowly progressive

Long smoking history

Dyspnea during exercise

Largely irreversible airflow limitation

Asthma

Onset early in life (often childhood) Symptoms vary from day to day Symptoms at night and early morning Allergy, rhinitis, and/or eczema are also present Family history of asthma Largely reversible airflow limitation

Congestive Heart Failure (CHF)

Fine basilar crackles on auscultation

Chest radiograph shows dilated heart, pulmonary edema

Pulmonary function tests indicate volume restriction, not airflow limitation

Bronchiectasis

Large volumes of purulent sputum Often associated with bacterial infection Coarse crackles/clubbing on auscultation

Chest radiograph or CT shows bronchial dilation or bronchial wall thickening

Tuberculosis (TB)

Onset all ages

Chest radiograph shows lung infiltrate

Microbiologic confirmation

High local prevalence of tuberculosis

Obliterative Bronchiolitis

Onset in younger age, nonsmokers

May have history of rheumatoid arthritis or fume exposure CT on expiration shows hypodense areas

Diffuse Panbronchiolitis

Most patients are male and nonsmokers. Almost all have chronic sinusitis.

Chest radiography and HRCT show diffuse small centrilobular nodular opacities and hyperinflation

From Global Initiative for Chronic Obstructive Lung Disease: Executive Summary: Global Strategy for the Diagnosis, Management, and Prevention of COPD, Updated 2008, p 39. http://www.goldcopd.com/Guidelineitem.asp?l1=2&l2=1&intId=996. *These features tend to be characteristic of the respective diseases but do not occur in every case. For example, a person who has never smoked may develop COPD, especially in the developing world where other risk factors may be more important than cigarette smoking, and asthma may develop in adult and even elderly patients.

COPD, Chronic obstructive pulmonary disease; CT, computed tomography; HRCT, high-resolution computed tomography.

COPD without a significant smoking history, or any patient developing COPD before age 45, should be screened for aj-antitrypsin deficiency. HRCT can help identify granulo-matous or interstitial lung diseases or provide evidence of bronchiectasis.

Spirometry is the key to making a formal diagnosis, as well as for staging the severity of illness. COPD may be diagnosed when obstructive lung disease is not fully reversible, defined as a postbronchodilator FVC of less than 80% of predicted in a patient with evidence of airway obstruction (FEVj/FVC ratio <70%). A pattern of restrictive lung disease (FVC <80% of predicted in presence of normal FEVj/FVC ratio) would suggest alternative diagnoses, such as pulmonary fibrosis, sarcoidosis, autoimmune conditions, or primary CHF.

Although there are several classification systems for severity of COPD, the American Thoracic Society (ATS) guidelines and the international GOLD standards are similar (Fig. 18-7). They are based on spirometric criteria—the presence of obstruction and the level of impairment in FEVj—and correlate strongly with quality of life and functional limitations. The 6-minute walk test is another way to stage COPD by its impact on daily activities. A distance of less than 149 meters walked in 6 minutes of encouraged walking indicates more severe functional limitation, and a distance farther than 350 m indicates minimal limitation (Celli et al., 2004).

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