Jennifer E. Fergeson, DO, Shiven S. Patel, MD, and Richard F. Lockey, MD
Asthma affects about 300 million people globally and accounts for 1 in every 250 deaths in the world. Approximately 12 million people in the United States each year experience an acute exacerbation of their asthma, a quarter of which require hospitalization.
Clinical estimates of severity based on an interview and physical examination can result in an inaccurate estimation of disease severity; audible wheezing is usually a sign of moderate asthma, whereas no wheezing can be a sign of severe airflow obstruction. Symptoms of severe asthma include chest tightness, cough (with or without sputum), sensation of air hunger, inability to lie flat, insomnia, and severe fatigue. The signs of severe asthma include use of accessory muscles of respiration, hyperinflation of the chest, tachypnea, tachycardia, diaphoresis, obtundation, apprehensive appearance, wheezing, inability to complete sentences,
and difficulty in lying down. Altered mental status, with or without cyanosis, is an ominous sign, and immediate emergency care and hospitalization are required. A detailed examination
should include examining for signs and symptoms of pneumonia, pneumothorax, or a pneumomediastinum, the latter of which can be investigated by means of palpation for subcutaneous crepitations, particularly in the supraclavicular areas of the chest wall.
Special attention should be paid to the patient’s blood pressure, pulse, and respiratory rate. Tachycardia and tachypnea might be suggestive of a moderate-to-severe exacerbation, whereas bradycardia might indicate impending respiratory arrest. Pulsus paradoxus is often present and might correlate with the severity of exacerbation (Fig 1)(.2,3,5,10)
DIFFERENTIAL DIAGNOSIS OF ACUTE ASTHMA
The differential diagnosis of acute asthma includes COPD, vocal cord dysfunction, bronchitis, bronchiectasis, epiglottitis, foreign body, extrathoracic or intrathoracic tracheal obstruction,
cardiogenic pulmonary edema, noncardiogenic pulmonary edema, pneumonia, pulmonary embolus, chemical pneumonitis, and hyperventilation syndrome.(3,5)
ACUTE ASTHMA TRIGGERS
Risk factors for asthma exacerbations can be identified from the clinical history. The patient interview should include questions about recent events, including (1) upper or lower respiratory tract infections; (2) cessation or reduction of medication; (3) use of concomitant medication, such as nonselective b-blockers; and (4) allergen or pollutant exposure.(2,10)