A 43-year-old man comes to the office due to occasional dyspnea that awakens him at night. This symptom started approximately a year ago after a severe upper respiratory tract infection, and since then he has also had an episodic cough. The patient has no other medical problems and takes no medications. He has no drug allergies and does not use tobacco, alcohol, or illicit drugs. His older brother has atopic dermatitis. Vital signs are normal. Lung auscultation reveals bilateral normal breath sounds with no wheezing or crackles. Heart sounds are normal, and there is no extremity edema. Pulmonary function tests are as follows: Administration of which of the following medications would be most useful during further diagnostic evaluation of this patient?

Question

A 43-year-old man comes to the office due to occasional dyspnea that awakens him at night.  This symptom started approximately a year ago after a severe upper respiratory tract infection, and since then he has also had an episodic cough.  The patient has no other medical problems and takes no medications.  He has no drug allergies and does not use tobacco, alcohol, or illicit drugs.  His older brother has atopic dermatitis.  Vital signs are normal.  Lung auscultation reveals bilateral normal breath sounds with no wheezing or crackles.  Heart sounds are normal, and there is no extremity edema.  Pulmonary function tests are as follows:  Administration of which of the following medications would be most useful during further diagnostic evaluation of this patient?

Quizplus · Accepted Answer

This patient's intermittent nocturnal dyspnea and episodic cough that began after a respiratory infection suggest a diagnosis of asthma, a disease characterized by airway inflammation and bronchial hyperreactivity to various stimuli, including physical, chemical, and allergenic irritants. Patients often have a family history of other diseases in the "allergic triad" (ie, allergic rhinitis, atopic dermatitis, asthma). Asthma is an obstructive airway disease (FEV1/FVC ≤70%); however, airflow obstruction is variable, and lung function studies may be normal between exacerbations. Bronchoprovocation testing can be useful in diagnosis when a patient presents with a history concerning for asthma but has normal spirometry values. Methacholine is an inhaled muscarinic cholinergic agonist that induces bronchoconstriction; patients are given increasing doses followed by serial spirometry. Patients with asthma demonstrate hyperresponsivity to bronchoprovocation with a reduction in FEV1 at lower doses than in those without asthma. Conversely, bronchodilator administration can help diagnose patients who have obstructive values on spirometry at baseline. Spirometry is performed before and after administration of a bronchodilator (eg, levalbuterol); reversal of the airflow obstruction after therapy suggests the diagnosis of asthma, while irreversible obstruction suggests an alternative diagnosis (eg, bronchiolitis, COPD). However, in a patient who is currently asymptomatic with normal lung function studies, this is unlikely to aid in diagnosis (Choice D). (Choice A) Epinephrine, an adrenergic agonist, is used for treatment of anaphylaxis. Patients can develop respiratory compromise due to swelling of the airways; however, this is typically accompanied by hypotension and skin involvement (eg, hives, lip swelling). Epinephrine is not indicated in the workup of asthma. (Choices B and F) Gadolinium is a contrast material used for MRI. Regadenoson is a coronary vasodilator used in cardiac stress testing to evaluate for coronary artery disease. Neither is indicated in the workup of asthma. (Choices C and G) Ipratropium bromide is a muscarinic cholinergic antagonist used for asthma and chronic obstructive pulmonary disease, and theophylline is a phosphodiesterase-3 inhibitor sometimes used for refractory asthma. These medications can treat asthma but are not used for diagnostic purposes. Educational objective: Asthma is characterized by reversible airway obstruction, and lung function tests may be normal between exacerbations. Bronchoprovocation can be used to aid diagnosis in patients with normal spirometry; methacholine is administered and followed by serial spirometry. Patients with asthma demonstrate hyperresponsivity to the stimulus, leading to FEV1 reductions at lower doses than in those without asthma. __________ References: A stepwise approach to the interpretation of pulmonary function tests. (http://www.ncbi.nlm.nih.gov/pubmed/24695507)

A 43-Year-Old Man Comes to the Office Due to Occasional