What are the main things I need to know about asthma for my internal medicine (IM) legacy end-of-rotation (EOR) exam?

Asthma Essentials for IM Legacy EOR Exam

For your exam, master the stepwise approach to asthma management: assess severity to initiate therapy, then assess control to adjust therapy—this is the fundamental framework that guides all clinical decisions 1.

Diagnosis

Key Clinical Features

• Classic triad: episodic wheezing, dyspnea, and cough (especially nocturnal or early morning)
• Variable symptoms that change over time and in intensity
• Reversible airflow obstruction is the hallmark

Diagnostic Testing

• Spirometry is essential for diagnosis in patients ≥5 years—don't rely on history and physical alone 1
• Look for:
  • Airflow obstruction (reduced FEV1/FVC ratio)
  • Reversibility: ≥12% and 200 mL improvement in FEV1 after bronchodilator
• Peak flow meters are for monitoring, NOT diagnosis due to high variability 1
• Bronchoprovocation testing (methacholine challenge) when spirometry is normal but asthma suspected—negative test helps rule out asthma 1

Diagnostic Pitfalls

• Cough-variant asthma: cough may be the only symptom, especially in children 1
• Vocal cord dysfunction (VCD): mimics asthma but doesn't respond to asthma medications; look for flattened inspiratory flow loop on spirometry 1
• Consider comorbidities: GERD, OSA, rhinitis, obesity—these complicate diagnosis and management 1

Classification System

Initial Assessment: Severity Classification

Use severity to initiate therapy in treatment-naive patients 1:

• Intermittent: symptoms ≤2 days/week, nighttime awakenings ≤2x/month, SABA use ≤2 days/week, no interference with activities
• Mild Persistent: symptoms >2 days/week (not daily), nighttime awakenings 3-4x/month
• Moderate Persistent: daily symptoms, nighttime awakenings >1x/week, daily SABA use, some limitation of activities
• Severe Persistent: symptoms throughout the day, nighttime awakenings often 7x/week, SABA use several times/day, extremely limited activities

Ongoing Management: Control Assessment

Once on therapy, assess control to adjust treatment 1:

• Well-controlled: symptoms ≤2 days/week, nighttime awakenings ≤2x/month, SABA use ≤2 days/week, no interference with activities, FEV1 >80% predicted
• Not well-controlled: symptoms >2 days/week, some limitation
• Very poorly controlled: symptoms throughout the day, extremely limited activities

Stepwise Treatment Approach

The Core Principle

• Step UP if control is inadequate
• Step DOWN if well-controlled for ≥3 months (to find minimum effective therapy)
• Never use SABA alone as monotherapy 2

Treatment Steps (Adults/Adolescents)

Step 1 (Intermittent): As-needed low-dose ICS-formoterol (preferred) 2

Step 2 (Mild Persistent): Daily low-dose ICS + as-needed SABA 1

Step 3 (Moderate Persistent): Two options 1:

• Preferred for impairment domain: Low-dose ICS + LABA (more consistent symptom improvement)
• Preferred for risk domain: Medium-dose ICS alone (if concerned about rare LABA-associated severe exacerbations)
• Adding LABA to low-dose ICS reduces exacerbations more than doubling ICS dose 1

Step 4: Medium-dose ICS + LABA

Step 5: High-dose ICS + LABA; consider omalizumab for allergic asthma

Step 6: High-dose ICS + LABA + oral corticosteroids; consider omalizumab

Critical LABA Safety Point

LABAs carry potential risk of rare life-threatening exacerbations—never use LABA without ICS 1. The decision to add LABA vs. increase ICS dose at Step 3 depends on whether impairment (symptoms) or risk (exacerbations) is your primary concern 1.

Acute Exacerbation Management

ED/Hospital Treatment

Bronchodilators:

• Albuterol nebulizer: 2.5-5 mg every 20 minutes for 3 doses, then as needed 1
• Ipratropium + albuterol: Add for severe exacerbations (can use up to 3 hours initially) 1

Systemic Corticosteroids (essential for moderate-severe exacerbations):

• Prednisone 40-80 mg/day (adults) or 1-2 mg/kg/day (children, max 60 mg/day) 1
• Continue until PEF reaches 70% predicted
• No advantage to IV over oral if GI absorption intact 1
• No need to taper if course <1 week, especially if on ICS 1

Outpatient Burst

• Prednisone 40-60 mg daily for 5-10 days (adults) 1
• 1-2 mg/kg/day (max 60 mg/day) for 3-10 days (children) 1

Special Situations

Exercise-Induced Bronchospasm (EIB)

• Anticipate in all asthma patients 1
• Diagnosis: ≥15% decrease in FEV1 or PEF after exercise challenge 1
• Treatment:
  • SABA 15-30 minutes before exercise (protective for 2-3 hours) 1
  • LABA protective up to 12 hours, but avoid chronic daily use for EIB alone—may mask poor control 1
  • Leukotriene receptor antagonists effective in ~50% 1

Pregnancy

• Maintaining control is critical for maternal and fetal health 1
• Uncontrolled asthma increases risk of perinatal mortality and pre-eclampsia 1

Goals of Therapy

Reduce Impairment 1

• Prevent chronic symptoms (day and night)
• Require SABA ≤2 days/week (excluding EIB prevention)
• Maintain normal pulmonary function
• Maintain normal activity levels

Reduce Risk 1

• Prevent exacerbations requiring ED visits/hospitalizations
• Prevent loss of lung function
• Minimize medication adverse effects

Key Exam Pearls

• Spirometry is mandatory for diagnosis—don't accept clinical diagnosis alone
• Assess severity initially, then assess control for ongoing management
• ICS are the foundation of persistent asthma treatment
• SABA use >2 days/week indicates inadequate control (step up therapy)
• Peak flow monitoring recommended for moderate-severe persistent asthma and those with poor symptom perception 1
• Systemic corticosteroids are essential for acute exacerbations—oral = IV efficacy
• VCD mimics asthma but doesn't respond to asthma meds—think of this in "difficult asthma"
• Comorbidities (GERD, OSA, rhinitis) must be addressed for optimal control