Differentials
COPD exacerbation
SIGNS / SYMPTOMS
Dyspnea is not progressive, and wheeze is bilateral. Symptoms of dyspnea, wheeze, and stridor are responsive to pharmacologic therapy (e.g., bronchodilators, corticosteroids, antibiotics).
INVESTIGATIONS
Pulmonary function tests: airflow obstruction with a reduced forced expiratory volume in 1 second (FEV1) and FEV1 to forced vital capacity (FVC) ratio; lung volumes show different degrees of hyperinflation and air trapping depending on severity; the diffusing capacity of the lung for carbon monoxide may be reduced.
CXR: flattened diaphragms and hyperinflation.
HRCT chest: areas of lung destruction, consistent with emphysematous change.
Asthma exacerbation
SIGNS / SYMPTOMS
It should be noted that not all conditions associated with wheeze are asthma.
Dyspnea is episodic and not progressive, and wheeze is bilateral. Symptoms of dyspnea and wheeze are responsive to pharmacologic therapy (e.g., bronchodilators, corticosteroids).
INVESTIGATIONS
Pulmonary function tests: during exacerbations, the forced expiratory volume in 1 second (FEV1) and FEV1 to forced vital capacity (FVC) ratio will be reduced, the diffusing capacity of the lung for carbon monoxide may be elevated.
Bronchodilator reversibility test: shows improvement following administration of bronchodilators.
Methacholine challenge: positive.
Pneumonia
SIGNS / SYMPTOMS
Symptoms of pyrexia, rigors, and cough productive of purulent sputum are characteristic.
Nonresolving or post-obstructive pneumonia related to CAO will not adequately respond clinically and radiographically to antibiotic therapy, and patients may experience persistent symptoms and CXR signs of infiltrates for >4 to 6 weeks.
INVESTIGATIONS
CXR: radiologically evident infiltrates that may be unilobar or multilobar.
Vocal cord dysfunction (VCD)
SIGNS / SYMPTOMS
The presentation of VCD may be quite dramatic, often simulating either CAO related to foreign-body aspiration or a severe asthma attack.
The clinical scenario and past medical history aid diagnosis.
Patients with VCD are often able to complete full sentences and can hold their breath, and the sounds of the attack disappear during a panting maneuver.[15][33]
On auscultation, the sounds in VCD are louder over the neck than in the chest.
INVESTIGATIONS
Pulmonary function tests: the flow-volume loop (FVL) shows a pattern of variable extrathoracic upper airway obstruction; "sawtoothing" or fluttering on the inspiratory limb, which represents fluctuations in the abnormal vocal cord motion, may be evident; and the FVL shows significant variability from test to test and may be normal in between attacks.[15]
Laryngoscopy: allows direct visualization of abnormal vocal cord motion.[15]
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