A 35-year-old woman is evaluated in an urgent care center for an acute exacerbation of asthma. She has a history of frequent asthma exacerbations requiring unscheduled visits; however, between these exacerbations, her examination and pulmonary function studies have been unremarkable. Her current medications are inhaled budesonide and inhaled albuterol.
On physical examination, she is in moderate distress with audible inspiratory and expiratory wheezing. Temperature is 37.0 °C (98.6 °F), pulse rate is 110/min, and respiration rate is 26/min. Monophonic inspiratory and expiratory wheezing is heard predominantly in the central lung fields. Other than tachycardia, the cardiac examination and remainder of the physical examination are normal.
She receives intravenous methylprednisolone and three nebulized albuterol-ipratropium bromide treatments. On follow-up evaluation 1 hour later, she still has wheezing, tachycardia, and tachypnea and is in moderate respiratory distress. Oxygen saturation is 96% breathing ambient air.
Which of the following is the most appropriate next step in management?
A: Chest radiograph
B: Intravenous magnesium sulfate
MKSAP Answer and Critique
The correct answer is C: Laryngoscopy. This item is available to MKSAP 16 subscribers as item 35 in the Pulmonary and Critical Care Medicine section.
The most appropriate next step in management is laryngoscopy. Patients with vocal cord dysfunction (VCD) have inspiratory and expiratory wheezing, respiratory distress, and anxiety. During attacks, VCD can be difficult to distinguish from asthma. Potential clues include sudden onset and abrupt termination of the attacks, lack of response to asthma therapy, prominent neck discomfort, lack of hypoxemia, and lack of hyperinflation on chest radiography. The distinction between the two conditions can be more difficult when patients have asthma as well as VCD. Laryngoscopy in symptomatic patients can reveal characteristic adduction of the vocal cords during inspiration. Alternatively, a flow-volume loop (in which the patient is asked to take a deep breath and then exhale while the inspiratory and expiratory flows are recorded) may be useful. In patients with VCD, the inspiratory limb of the flow-volume loop is “cut off” owing to narrowing of the extrathoracic airway (at the level of the vocal cords) during inspiration. The expiratory flows are preserved. Recognizing VCD is essential to avoid treating patients with repeat courses of systemic corticosteroids and other therapies for severe asthma while delaying the start of therapies targeted at VCD. These include speech therapy, relaxation techniques, and treatment of underlying causes such as anxiety, postnasal drip, and gastroesophageal reflux.
Chest radiograph in patients with acute asthma is not indicated unless the patient does not respond to initial therapy, has severe exacerbations, has clinical evidence of a concurrent illness (such as fever to suggest pneumonia, or crackles and leg edema to suggest heart failure), has evidence of a complication (subcutaneous air, asymmetric breath sounds that may suggest pneumothorax), or requires hospitalization.
Intravenous magnesium sulfate can be considered in acute asthma exacerbations, but it has no role in treating VCD.
There is no indication for antibiotics in this patient even if an acute asthma exacerbation were suspected.
- Potential clues for vocal cord dysfunction include sudden onset and abrupt termination of attacks, lack of response to asthma therapy, prominent neck discomfort, and lack of hypoxemia.
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