Prepare for the Step 2 USMLE® with this comprehensive topic on asthma management. Follow the case of a 42-year-old man in a pulmonology clinic, diagnosed with asthma and currently on a prescribed inhaler. Explore the patient’s symptoms, spirometry results, and laboratory findings to determine the most appropriate next step in his management. Ideal for medical students and professionals seeking a thorough understanding of asthma assessment and treatment strategies to excel in the USMLE exam and real-world clinical practice.
A 42-year-old man is evaluated in the pulmonology clinic for a follow-up visit for asthma that was diagnosed one month ago after spirometry showed an FEV1/FVC ratio of 0.6 and an increase in FEV1 of 15% after albuterol administration. The patient was started on a daily low-dose inhaled corticosteroids (ICS)-long-acting beta-agonists(LABA) inhaler and has noticed an improvement in his symptoms. The patient wakes up short of breath several times weekly and needs to use a short-acting albuterol inhaler several times a day. Physical exam reveals diffuse bilateral wheezing. Serum IgE is 10 IU/mL, and eosinophils are 50 cells/µL. High-resolution CT of the chest is within normal limits. Which of the following is the most appropriate next step in management?A. Change the ICS-LABA inhaler to a medium dose
B. Consider an alternative diagnosis
C. Add a long-acting muscarinic antagonist inhaler
D. Make no changes and reevaluate the patient in one week
E. Start omalizumab or mepolizumab
The correct answer to today’s USMLE® Step 2 CK Question is…
A. Change the ICS-LABA inhaler to a medium dose
Before we get to the Main Explanation, let’s see why the answer wasn’t B, C, D, or E. Skip to the bottom if you want to see the correct answer right away!
Incorrect answer explanations
B. Consider an alternative diagnosis
Incorrect: This patient’s spirometry (PFT) findings suggest asthma. COPD and vocal cord paralysis are in the differential diagnosis, but are not indicated by the findings in this vignette.
C. Add a long-acting muscarinic antagonist inhaler
Incorrect: Patients with inadequately controlled asthma should have their ICS-LABA inhaler increased to a high dose before adding a LAMA (long-acting muscarinic antagonist) inhaler. This patient is only on a low-dose ICS-LABA inhaler.
D. Make no changes and reevaluate the patient in one week
Incorrect: This patient’s asthma is poorly controlled, and making no changes to therapy is inappropriate.
E. Start omalizumab or mepolizumab
Incorrect: These medications are monoclonal antibodies indicated for use in severe, uncontrolled asthma with specific lab abnormalities (IgE >30 IU/mL for omalizumab and eosinophils >150 cells/µL for mepolizumab).
Main Explanation
Asthma is an obstructive lung disease characterized by episodic inflammation and hyperresponsiveness of bronchial smooth muscles leading to shortness of breath and wheezing. Treatment is directed at reducing inflammation (steroids) and relaxing bronchial smooth muscle (beta-agonists and muscarinic antagonists). Inhaled medications include short-acting beta-agonists (SABA), long-acting beta-agonists (LABA), inhaled corticosteroids (ICS), and long-acting muscarinic antagonists (LAMA).
Patients with mild symptoms should be started on an as-needed low-dose ICS-LABA. If more control is needed, this regimen can be changed to a daily low-dose ICS with or without an as-needed SABA for rescue therapy. If a patient’s asthma continues to be partially controlled, they should switch to a daily low-dose ICS-LABA, again adding a SABA for rescue therapy. If patients are still poorly managed, the next step is changing to a daily medium-dose ICS-LABA and, eventually, a daily high-dose ICS-LABA. If asthma is still poorly controlled, other medications should be considered, such as an inhaled LAMA or biological agents (e.g., mepolizumab, omalizumab).
For acute asthma exacerbations, including those in status asthmaticus, patients should receive supplemental oxygen, inhaled bronchodilators including a short-acting muscarinic antagonist like ipratropium and a short-acting beta agonist or SABA like albuterol, and systemic corticosteroids. If a patient doesn’t respond to this treatment, then a single dose of IV magnesium may be administered. If they do not respond to these measures, patients should be considered for non-invasive ventilation (e.g. bi-level positive airway pressure) or endotracheal intubation and mechanical ventilation. Mechanical ventilation should be considered for any patient with altered mental status, cyanosis, inability to maintain respiratory effort, and worsening hypercapnia and respiratory acidosis.
Major Takeaway
Asthma treatment follows a stepwise approach that begins with an as-needed low-dose ICS-LABA for mild symptoms. After that, daily inhalers should be given and changed in the following order: low-dose ICS, low-dose ICS-LABA, medium-dose ICS-LABA, high-dose ICS-LABA. Eventually biologics may be needed if the patient meets criteria for them.
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