A Patient Presents With Episodes Bronchospasm.

A 21-year-old woman with no significant past medical history presents with a 2-month history of episodic shortness of breath. These symptoms began with an upper respiratory tract infection. She has fits of coughing and trouble catching her breath with exertion. She states that her breath “sounds like whistles” at times. She tried a friend’s albuterol inhaler with some improvement
and wonders if she has asthma.
On examination, she is breathing comfortably at 16 times per minute and her oxygen saturation is 96% on room air. Her lungs are clear to auscultation, and the remainder of her exam is unremarkable. You want to better categorize this patient’s disease.

Which of the following tests is most appropriate to order now?
A) Spirometry.
B) Chest x-ray.
C) Arterial blood gas (ABG).
D) Methacholine challenge.
E) Chest CT.

Answer And Discussion

The correct answer is “A.” Spirometry.

Since this patient has symptoms of bronchospasm, spirometry will be essential in determining if there is objective evidence of obstructive lung disease. However, spirometry results are often normal in mild cases of asthma, especially when the patient is asymptomatic.
Bronchoprovocation testing, with methacholine or histamine, may be useful in such cases, but should follow basic spirometry.
Although chest radiography (x-ray or CT) may reveal an unsuspected process, it is not indicated in otherwise healthy patients with symptoms of bronchospasm. Bacterial pneumonia is a potential precipitant of bronchospasm that may be diagnosed on chest x-ray, but this patient has no constitutional symptoms (like fever) associated with serious bacterial infection.
ABG levels may be helpful when a patient presents with respiratory distress but certainly not in the office setting.

HELPFUL TIP: A normal blood gas in a patient with an asthma exacerbation and tachypnea
is an ominous sign that signals impending respiratory failure. The carbon dioxide (PaCO2) should be low in a patient with tachypnea. Thus, a normal appearing ABG with a normal carbon dioxide level is an indication of respiratory muscle fatigue and early respiratory failure.