Differentials
Asthma
SIGNS / SYMPTOMS
Onset of asthma is usually in early life. A personal or family history of allergy, rhinitis, and eczema is often present. There is daily variability in symptoms, and patients have overt wheezing that usually rapidly responds to bronchodilators. Cough variant asthma mimics many features of COPD.
INVESTIGATIONS
Spirometry shows reversibility with bronchodilators. Pulmonary function tests show reversibility with bronchodilators and no decrease in diffusing capacity of the lung for carbon monoxide (DLCO). Sputum or blood eosinophilia is suggestive of asthma, although may also be present in COPD.
Congestive heart failure
SIGNS / SYMPTOMS
Usually a history of cardiovascular diseases is present. Patients report symptoms of orthopnea, and fine bibasilar inspiratory crackles may be heard on auscultation.
INVESTIGATIONS
B-type natriuretic peptide levels are usually elevated, and chest x-ray reveals increased pulmonary vascular congestion. Transthoracic echocardiogram establishes the structure and function of the left ventricle.
Bronchiectasis
SIGNS / SYMPTOMS
There may be a history of recurrent infection in childhood. Large volume of purulent sputum is usually present. Coarse crackles may be heard on auscultation. History of pertussis or tuberculosis is a clue to diagnosis.
INVESTIGATIONS
Chest CT reveals bronchial dilation and bronchial wall thickening.
Tuberculosis
SIGNS / SYMPTOMS
A history of fever, night sweats, weight loss, and chronic productive cough is usually present. Tuberculosis is more common in people living in or originating from endemic areas.
INVESTIGATIONS
The diagnosis requires microbiologic confirmation. Infiltrates, fibrosis, or granuloma seen on chest x-ray or chest CT may suggest tuberculosis. Patients usually have positive skin test for tuberculosis.
Bronchiolitis
SIGNS / SYMPTOMS
Bronchiolitis may affect patients at younger ages. The patient may have a history of connective tissue disorders, especially rheumatoid arthritis, or fume exposure. Some cases are postinfectious.
INVESTIGATIONS
Pulmonary function tests in bronchiolitis can present with obstructive, restrictive, or mixed pattern. Chest x-ray shows hyperinflation. High-resolution chest CT may show diffuse, small, centrilobular nodular opacities, but is rarely done in children due to radiation risk.
Upper airway dysfunction
SIGNS / SYMPTOMS
Can affect patients of any age. History of prior trauma or intubation is very helpful. Lung examination is usually normal, but signs of upper airway restriction, such as wheezing and stridor, may be present. Patients may have voice hoarseness if vocal cords are involved.
INVESTIGATIONS
The flow-volume curve in pulmonary function testing may reveal a characteristic expiratory or inspiratory plateau, or both. Diagnosis is confirmed by direct visualization of the affected airway by endoscopy.
Chronic rhinosinusitis/postnasal drip
SIGNS / SYMPTOMS
Chronic rhinosinusitis is a very common cause of chronic cough. Patients may complain of sinus pressure, rhinorrhea, nonproductive cough, and/or headache.
INVESTIGATIONS
Nasal endoscopy, CT of sinuses, and/or empiric trial of antihistamines are commonly utilized to aid in diagnosis.
Gastroesophageal reflux disease (GERD)
SIGNS / SYMPTOMS
Patients with GERD often have dyspepsia and frequent belching, and can have a chronic cough that worsens at night when supine.
INVESTIGATIONS
Diagnosis is usually based on response to empiric therapy with proton-pump inhibitors.
ACE inhibitor-induced chronic cough
SIGNS / SYMPTOMS
ACE inhibitors can cause chronic cough; however, the cough is usually nonproductive.
INVESTIGATIONS
Diagnosis is usually based on improvement of symptoms after empiric cessation of ACE inhibitor.
Lung cancer
SIGNS / SYMPTOMS
Patients may have weight loss, night sweats, hemoptysis, and/or chest or back pain.
People with COPD are also at increased risk of lung cancer.
INVESTIGATIONS
Radiography is important in the assessment for lung cancer. Bronchoscopy may be necessary to evaluate for endobronchial cancer if suspicion is high.
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