Pulmonology is the subspecialty of internal medicine concerned with diseases of the lungs and airways. Pulmonologists treat respiratory disorders and may also specialize in sleep disorders, severe allergies and asthma, and other lung diseases. Some pulmonologists subspecialize in critical care medicine.
Pulmonary Disorders Chapters (A-Z)
Acute bronchitis is inflammation of the tracheobronchial tree, commonly following a URI, that occurs in patients without chronic lung disorders. The cause is almost always a viral infection. The pathogen is rarely identified. The most common symptom is cough, with or without fever, and possibly sputum production. Diagnosis is based on clinical findings. Treatment is supportive; antibiotics are usually unnecessary. Prognosis is excellent.
Approach to the Pulmonary Patient
Key components in the evaluation of patients with pulmonary symptoms are the history, physical examination, and, in most cases, a chest x-ray. These components establish the need for subsequent testing, which may include pulmonary function testing and ABG analysis (see Overview of Tests of Pulmonary Function), CT or other imaging tests (see Chest Imaging), and bronchoscopy (see Bronchoscopy).
Asthma and Related Disorders
Bronchiectasis and Atelectasis
Bronchiectasis is dilation and destruction of larger bronchi caused by chronic infection and inflammation. Common causes are cystic fibrosis, immune defects, and recurrent infections, though some cases seem to be idiopathic. Symptoms are chronic cough and purulent sputum expectoration; some patients may also have fever and dyspnea. Diagnosis is based on history and imaging, usually involving high-resolution CT, though standard chest x-rays may be diagnostic. Treatment and prevention of acute exacerbations are with antibiotics, drainage of secretions, and management of complications, such as superinfection and hemoptysis. Treatment of underlying disorders is important whenever possible.
Chronic Obstructive Pulmonary Disease and Related Disorders
Chronic obstructive pulmonary disease (COPD) is partially reversible airflow limitation caused by an inflammatory response to inhaled toxins, often cigarette smoke. α 1 -Antitrypsin deficiency and various occupational exposures are less common causes in nonsmokers. Symptoms are productive cough and dyspnea that develop over years; common signs include decreased breath sounds, prolonged expiratory phase of respiration, and wheezing. Severe cases may be complicated by weight loss, pneumothorax, frequent acute decompensation episodes, right heart failure, and acute or chronic respiratory failure. Diagnosis is based on history, physical examination, chest x-ray, and pulmonary function tests. Treatment is with bronchodilators, corticosteroids, and, when necessary, O 2 and antibiotics. About 50% of patients with severe COPD die within 10 yr of diagnosis.
Diagnostic Pulmonary Procedures
Diagnostic tests besides pulmonary function testing (see Tests of Pulmonary Function (PFT)) include various types of chest imaging, electrocardiography, and ventilation/perfusion scanning. Diagnostic procedures include bronchoscopy, mediastinoscopy and mediastinotomy, pleural biopsy, thoracentesis, thoracoscopy and video-assisted thoracoscopic surgery, thoracotomy, transthoracic needle biopsy, and tube thoracostomy. Pulmonary artery catheterization is discussed elsewhere (see Vascular Access). Therapeutic procedures, including chest physiotherapy and pulmonary rehabilitation, are discussed elsewhere (see Pulmonary Rehabilitation).
Diffuse Alveolar Hemorrhage and Pulmonary-Renal Syndrome
Some disorders that cause diffuse alveolar hemorrhage are associated with glomerulonephritis; then the disorder is defined as a pulmonary-renal syndrome (see Pulmonary-Renal Syndrome).
Environmental Pulmonary Diseases
Environmental pulmonary diseases result from inhalation of dusts, allergens, chemicals, gases, and environmental pollutants. The lungs are continually exposed to the external environment and are susceptible to a host of environmental diseases. Pathologic processes can involve any part of the lungs, including the airways (eg, in occupational asthma, reactive airways dysfunction syndrome, or toxic inhalations), interstitium (eg, in pneumoconioses or hypersensitivity pneumonitis), and pleura (eg, in asbestos-related diseases).
Interstitial Lung Diseases
Interstitial lung diseases are a heterogeneous group of disorders characterized by alveolar septal thickening, fibroblast proliferation, collagen deposition, and, if the process remains unchecked, pulmonary fibrosis. Interstitial lung diseases can be classified using various criteria (eg, acute vs chronic, granulomatous vs nongranulomatous, known cause vs unknown cause, primary lung disease vs secondary to systemic disease).
Lung abscess is a necrotizing lung infection characterized by a pus-filled cavitary lesion. It is most commonly caused by aspiration of oral secretions by patients who have impaired consciousness. Symptoms are persistent cough, fever, sweats, and weight loss. Diagnosis is based primarily on chest x-ray. Treatment usually is with clindamycin or combination β-lactam/β-lactamase inhibitors.
Mediastinal and Pleural Disorders
(See also Neonatal Pneumonia.)
Pulmonary Embolism (PE)
Pulmonary embolism is the occlusion of ≥ 1 pulmonary arteries by thrombi that originate elsewhere, typically in the large veins of the legs or pelvis. Risk factors for pulmonary embolism are conditions that impair venous return, conditions that cause endothelial injury or dysfunction, and underlying hypercoagulable states. Symptoms of pulmonary embolism are nonspecific and include dyspnea, pleuritic chest pain, and, in more severe cases, light-headedness, presyncope, syncope, or cardiorespiratory arrest. Signs are also nonspecific and may include tachypnea, tachycardia, and in more severe cases, hypotension. Diagnosis of pulmonary embolism is accomplished with CT angiography, ventilation/perfusion scanning, or occasionally, pulmonary arteriography. Pulmonary embolism treatment is with anticoagulants and, sometimes, clot dissolution with thrombolytics or surgical removal. When anticoagulation is contraindicated, an inferior vena caval filter should be placed. Preventive measures include anticoagulants and/or mechanical compression devices that are applied to the legs in hospitalized patients.
Pulmonary hypertension is increased pressure in the pulmonary circulation. It has many secondary causes; some cases are idiopathic. In pulmonary hypertension, pulmonary vessels become constricted. Severe pulmonary hypertension leads to right ventricular overload and failure. Symptoms are fatigue, exertional dyspnea, and, occasionally, chest discomfort and syncope. Diagnosis is made by finding elevated pulmonary artery pressure (estimated by echocardiography and confirmed by right heart catheterization). Treatment is with pulmonary vasodilators and diuretics. In some advanced cases, lung transplantation is an option. Prognosis is poor overall if a treatable secondary cause is not found.
Chest physiotherapy consists of external mechanical maneuvers, such as chest percussion, postural drainage, and vibration, to augment mobilization and clearance of airway secretions. It is indicated for patients in whom cough is insufficient to clear thick, tenacious, or loculated secretions. Examples include patients with cystic fibrosis, bronchiectasis, lung abscess, neuromuscular disorders, and pneumonias in dependent lung regions.
Sarcoidosis is a disorder resulting in noncaseating granulomas in one or more organs and tissues; etiology is unknown. The lungs and lymphatic system are most often affected, but sarcoidosis may affect any organ. Pulmonary symptoms range from none to exertional dyspnea and, rarely, lung or other organ failure. Diagnosis usually is first suspected because of pulmonary involvement and is confirmed by chest x-ray, biopsy, and exclusion of other causes of granulomatous inflammation. First-line treatment is corticosteroids. Prognosis is excellent for limited disease but poor for more advanced disease.
Symptoms of Pulmonary Disorders
Tests of Pulmonary Function (PFT)
Pulmonary function tests provide measures of airflow, lung volumes, gas exchange, response to bronchodilators, and respiratory muscle function. Basic pulmonary function tests available in the ambulatory setting include spirometry and pulse oximetry; these tests provide physiologic measures of pulmonary function and can be used to quickly narrow a differential diagnosis and suggest a subsequent strategy of additional testing or therapy. More complicated testing includes measurement of lung volumes; lung, chest wall, and respiratory system compliance (which requires measurement of esophageal pressure); and complete cardiopulmonary exercise testing. These tests provide a more detailed description of physiologic abnormalities and the likely underlying pathology. The choice and sequence of testing are guided by information taken from the history and physical examination.