Emphysema
The most common cause of death from respiratory disease in the United States, emphysema is one of several diseases labeled collectively as chronic obstructive pulmonary disease (COPD).
Emphysema appears to be more prevalent in males than in females. Postmortem findings reveal few adult lungs without some degree of emphysema.
Causes
Emphysema may be caused by a deficiency of alpha1-antitrypsin (AAT) and by cigarette smoking. Recurrent inflammation associated with the release of proteolytic enzymes from lung cells causes the air spaces distal to the terminal bronchioles to enlarge abnormally and irreversibly. This leads to the destruction of alveolar walls, which results in a breakdown of elasticity.
Complications
Recurrent respiratory tract infections, cor pulmonale, and respiratory failure may complicate emphysema. Between 20% and 25% of patients with COPD develop peptic ulcer disease. In addition, alveolar blebs and bullae may rupture, leading to spontaneous pneumothorax or pneumomediastinum.
Assessment
The patient’s history may disclose that he is a longtime smoker. He may report shortness of breath, a chronic cough and, possibly, anorexia with resultant weight loss and a general feeling of malaise.
Inspection may show a barrel-chested patient who breathes through pursed lips and uses accessory muscles to facilitate breathing. You may notice peripheral cyanosis, clubbed fingers and toes, and tachypnea.
Palpation may reveal decreased tactile fremitus and decreased chest expansion. Percussion may disclose hyperresonance. On auscultation, you may hear decreased breath sounds, crackles and wheezing during inspiration, a prolonged expiratory phase with grunting respirations, and distant heart sounds.
Diagnostic tests
Chest X-rays in advanced disease may show a flattened diaphragm, reduced vascular markings at the lung periphery, overaeration of the lungs, a vertical heart, enlarged anteroposterior chest diameter, and a large retrosternal air space.
Pulmonary function tests typically indicate increased residual volume and total lung capacity, reduced diffusing capacity, and increased inspiratory flow.
Arterial blood gas (ABG) analysis usually shows reduced partial pressure of oxygen in arterial blood and normal partial pressure of carbon dioxide in arterial blood until late in the disease.
Electrocardiography may reveal tall, symmetrical P waves in leads II, III, and aVF; a vertical QRS complex; and signs of right ventricular hypertrophy late in the disease.
Red blood cell (RBC) count usually demonstrates an increased hemoglobin level late in the disease when the patient has persistent severe hypoxia.
