Classification of Chronic Obstructive Pulmonary Disease by Severity

Stage	Characteristics
I (mild COPD)	Chronic symptoms (cough, sputum production) FEV1/FVC < 70% FEV1 ≥ 80% of predicted
II (moderate COPD)	With or without chronic symptoms FEV1/FVC < 70% 50% of predicted ≤ FEV1 < 80% of predicted
III (severe COPD)	With or without chronic symptoms FEV1/FVC < 70% 30% of predicted ≤ FEV1 < 50% of predicted
IV (very severe COPD)	With or without chronic symptoms FEV1/FVC < 70% FEV1 < 30% of predicted or < 50% of predicted plus the presence of respiratory failure or clinical signs of right heart failure increase.

FEV¹ - forced expiratory volume in 1 second; FVC - forced vital capacity.

Clinical features

Patients who have smoked > 20 cigarettes per day for > 20 yr may develop a productive cough in their 40s or early 50s. Exertional dyspnea usually does not become severe enough to warrant a visit to a physician until COPD patients are in their 50s lo mid-60s. Sputum production is insidious in onset, initially occurring only in the morning. Daily volume rarely exceeds 60 mL. Sputum is usually mucoid but becomes purulent during an exacerbation.

Acute chest illnesses-characterized by increased cough, purulent sputum, wheezing, dyspnea, and occasionally fever-may occur from time to time. (A history of wheezing and dyspnea may lead to the erroneous diagnosis of asthma.) As COPD progresses, the intervals between acute exacerbations tend to become shorter. Late in the disease, an exacerbation may cause severe hypoxemia with cyanosis, which is accentuated if erythrocytosis is present. Morning headache may indicate hypercapnia. Hypercapnia with more severe hypoxemia, sometimes with erythrocytosis, is common in end-stage disease. Weight loss occurs in some patients.

Objective examination. Early in COPD, physical examination of the chest may not be remarkable except for auscultation of expiratory wheezes. As airway obstruction progresses, hyperinflation of the lungs becomes evident. The anteroposterior diameter of the chest in creases because the lungs are near full inspiration and because emphysema increases total lung capacity. The diaphragm is depressed, and its motion limited. Breath sounds are decreased, and heart sounds become distant. Signs of pulmonary hypertension and right ventricular hypertrophy are usually not detectable because emphysematous lung tissue is interposed between the heart and anterior chest wall. A few coarse crackles are often heard at the lung bases. An enlarged, tender liver indicates heart failure. Neck vein distention, especially during expiration, may occur in the absence of heart failure because of increased intrathoracic pressure. Asterixis may accompany severe hypercapnia.

The patient with end-stage COPD is often a dramatic sight - standing before a counter leaning forward with arms outstretched and weight supported on the palms. The accessory respiratory muscles of the neck and shoulder girdle are in full use. Expiration often occurs through pursed lips. The chest appears overinflated, often with paradoxic in drawing of the lower interspaces. Cyanosis may be present.