Asthma

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Pearls

1. Avoid SABA monotherapy; prioritize ICS-formoterol as the new reliever therapy given the fast onset of formoterol. It can be used as a maintenance inhaler if more control is needed. Avoid salmeterol due to delayed onset.
2. For patients with a SABA who are  unable to obtain access to ICS-formoterol, tell them to use an ICS inhaler whenever they use their SABA. 
3. Clinical history is important. In addition to assessing asthma triggers like dust, wildfires, and pollen, ask about a  history of premature birth (before 34 weeks) as this increases the risk of bronchopulmonary dysplasia and underdeveloped terminal airways, which is a risk factor for asthma.
4. Spirometry should be used to diagnose asthma, but peak expiratory flow (PEF) can be used if spirometry is unavailable. 
5. When spirometry is normal during asymptomatic periods, use bronchoprovocation testing with methacholine to confirm airway hyperresponsiveness. This is particularly sensitive for diagnosing asthma.
6. Utilize the ACT questionnaire to assess and monitor asthma control over time. Scores below 20 suggest poorly-controlled asthma and should prompt therapy adjustments.
7. Refer early for severe or poorly-controlled asthma, asthma-COPD overlap, or obesity-associated asthma. 
8. Use personal PEF measurements to assist in creating an asthma action plan, which can aid in diagnosing and triaging asthma exacerbations.
9. Encourage healthy weight management, regular exercise, routine vaccination, and pulmonary rehabilitation to improve asthma outcomes.

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Conducting the Initial Interview

Patient History

• Start with an open-ended question, then assess specific triggers
• Environmental factors: dust, pollen, air quality, wildfires
• Physical activity as a trigger
• Family history of asthma or lung disease
• Childhood history: premature birth (before 34 weeks) linked to bronchopulmonary dysplasia
• Ask about childhood asthma and why symptoms may improve with age

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Making the Diagnosis of Asthma

Gold Standard: Spirometry

• Obstructive airway disease with reversibility after bronchodilator
• FEV1/FVC reduction alone is not enough for diagnosis
• FEF 25-75% can indicate early-stage obstruction

PFT Findings in Asthma

Test	Findings in Asthma	Notes
FEV1/FVC Ratio	↓ (Reduced) (<0.75-0.80)	Hallmark of obstructive lung disease
FEV1 (Post-Bronchodilator)	↑ by ≥12% and ≥200 mL improvement	Confirms reversible airway obstruction
FEF 25-75%	↓ (Reduced)	Suggests early small airway involvement
TLC (Total Lung Capacity)	Normal or ↑	Hyperinflation may occur in severe cases
RV (Residual Volume)	↑ (Increased)	Air trapping due to airway obstruction
DLCO (Diffusion Capacity)	Normal	Differentiates from COPD (which may have ↓ DLCO)
Methacholine Challenge	FEV1 ↓ by ≥20% at low doses	Indicates airway hyperreactivity when spirometry is normal

Key Takeaway:

• Reversible obstruction is the hallmark of asthma
• Methacholine challenge is useful when spirometry is normal but asthma is suspected

Bronchoprovocation Testing

• Needed if spirometry is normal during asymptomatic periods
• Methacholine challenge to assess hyperreactivity
• Exercise test for exercise-induced bronchoconstriction

Considerations for Pregnant Patients

• Spirometry may be confounded but can still be attempted
• Asthma control changes: one-third improve, one-third worsen, one-third remain stable

Is Spirometry Always Necessary?

• Essential for diagnosis but can be skipped in select cases
• Empiric ICS-formoterol trial may be reasonable if spirometry is unavailable

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Peak Expiratory Flow (PEF) Testing

• Best for monitoring asthma over time
• Can be used for diagnosis in resource-limited settings
• Assess >10% variability over two weeks
• Bronchodilator response: >20% increase suggests asthma

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Staging Asthma

1. Symptoms only in specific circumstances
2. Mild but persistent symptoms
3. Severe symptoms interfering with daily life

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The Asthma Control Test (ACT)

• Validated questionnaire for symptom control
• Five questions assessing symptoms, inhaler use, and perception of control
• Score ≥20 = well-controlled, ≤19 = not well-controlled

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Asthma Management

Formoterol + ICS (Symbicort) as the New Albuterol

• Superior to albuterol monotherapy
• If mild symptoms -> 2 puffs Symbicort prior to trigger exposure with additional puffs as needed (max 12/day)
• If symptoms worsen/poorly controlled -> 2 puffs Symbicort BID as maintenance with additional doses PRN for symptom relief
• Addresses airway inflammation while providing symptom relief
• Reduces exacerbations and systemic steroid use
• Formoterol preferred over salmeterol due to rapid onset (5-10 min vs 2 hours)
• Albuterol-ICS may be an alternative for patients reluctant to switch to formoterol

Practical Application

• PRN ICS-formoterol for mild asthma
• Maintenance And Reliever Therapy (MART) for worsening symptoms
• High-dose therapy for frequent exacerbations, step down once controlled

Cost-Conscious Options

• If ICS-formoterol is too expensive, use separate ICS and bronchodilator inhalers

Montelukast

• Adjunct for allergic, exercise-induced, or aspirin-sensitive asthma
• Risk of neuropsychiatric side effects (black box warning)
• Not used as monotherapy except possibly for cough-variant asthma

Theophylline

• Rarely used due to narrow therapeutic window and side effects
• Mentioned in GINA for resource-limited settings but largely obsolete

Optimizing Therapy

• Proper inhaler technique and use of spacers improve efficacy
• Adjust ICS dose based on symptoms and side effects

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Nonpharmacologic Measures

• Weight management improves asthma control
• Encourage exercise, reframe as "asthma with exertional trigger"
• Identify and avoid triggers
• Refer to pulmonary rehabilitation
• Symptom journaling helps track patterns
• Stay up to date on vaccines (influenza, RSV, COVID-19, pneumonia)

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Asthma Exacerbations

PEF and Asthma Action Plans

• Establish a baseline PEF to monitor exacerbations
• Green: 100-80%, well-controlled
• Yellow: 50-80%, increase meds, consider systemic steroids
• Red: <50%, urgent treatment, possible ED visit

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Emergency Department Criteria

• Speaking in short sentences (4-5 words)
• Severe respiratory distress
• Rule out alternative diagnoses like CHF or infections

Azithromycin

• May reduce exacerbations in severe asthma
• Potential benefit for eosinophilic and noneosinophilic asthma

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Persistent Asthma Symptoms

Specialist Referral

• Early referral for severe, uncontrolled, or complex asthma
• Consider referral for biologic therapy assessment

Comprehensive Workup

• CBC with eosinophils, high-resolution CT
• Rule out mimickers: pro-BNP, ANCA, echocardiography

Asthma Phenotypes

• High T2 Inflammation: Allergic asthma, high eosinophils, responds to ICS and biologics
• Low T2 Asthma: Poor response to biologics, limited treatment options
• Cough-variant Asthma: Montelukast may help
• Obesity-associated Asthma: Unique pathophysiology, often harder to control