Pulmonary Fibrosis
Pulmonary fibrosis is a chronic and often fatal interstitial pulmonary disease. Approximately 50% of patients with pulmonary fibrosis die within 5 years of diagnosis. Once thought to be a rare condition, it’s now diagnosed with much greater frequency. Pulmonary fibrosis has been known by numerous names over the years, such as cryptogenic fibrosing alveolitis, diffuse interstitial fibrosis, idiopathic interstitial pneumonitis, and Hamman-Rich syndrome.
The incidence of pulmonary fibrosis is slightly higher in males than females, and in smokers than nonsmokers. It most commonly occurs in people ages 50 to 70 and rarely appears in patients younger than age 40 or older than age 80. Pulmonary fibrosis is one of several types of interstitial lung diseases, all of which should be ruled out before a diagnosis of pulmonary fibrosis is confirmed.
Causes
Pulmonary fibrosis is the result of a cascade of events that involve inflammatory, immune, and fibrotic processes in the lung. Despite many studies, the stimulus that begins the progression remains unclear. Speculation has revolved around viral and genetic causes, but no good evidence has been found to support either theory. However, it’s clear that chronic inflammation plays an important role. Inflammation causes the injury and the fibrosis that ultimately affects and impairs the structure and function of the alveolo-capillary gas exchange surface. Furthermore, conditions such as ilicosis and asbestosis can lead to fibrosis of the lung tissue.
Complications
Complications of pulmonary fibrosis include a dry, hacking, often paroxysmal cough. Most patients have these symptoms for several months to up to 2 years before seeking medical attention. Endexpiratory crackles, especially in the bases of the lungs are often heard with this condition. Rapid, shallow breathing occurs, often with exercise, and clubbing has been noted in more than 40% of the affected patients. Late in the disease progress, cyanosis and evidence of pulmonary hypertension commonly occur. As the disease progresses, profound hypoxemia and severe, debilitating dyspnea are the hallmark signs.
Assessment
The patient’s history may reveal typical presenting symptoms such as a dry, hacking, and often paroxysmal cough. When pulmonary fibrosis is suspected, a thorough investigation of the patient’s history is essential to exclude more common causes of interstitial lung disease. Take particular note of the patient’s reports of:
environmental and occupational exposures to such agents as coal dust, asbestos, silica, and beryllium
connective tissue disorders such as scleroderma and rheumatoid arthritis
exposure to certain drugs, such as amiodarone, tocainide, and crack cocaine.
Physical examination may reveal clubbing of the fingertips and cyanosis. Rapid, shallow breathing may also be noted. Auscultation of the lungs often reveals expiratory crackles, especially in the bases of the lungs. Pulmonary hypertension with an augmented S2and S3 may also be present.
Later in the disease process, auscultation may reveal the bronchial breath sounds that occur when airway consolidation develops. Profound hypoxemia and severe dyspnea that greatly limits activity may be noted as the disease progresses.
Diagnostic tests
The following tests aid in the diagnosis of pulmonary fibrosis:
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