How to diagnose and treat exercise-induced bronchoconstriction (EIB)?

Exercise-Induced Bronchoconstriction: Diagnosis and Treatment

Diagnose EIB through objective bronchoprovocation testing—never rely on symptoms alone—and treat with pre-exercise short-acting β2-agonists as first-line therapy, reserving daily inhaled corticosteroids for patients with underlying asthma or inadequate control. 1

Diagnostic Approach

Initial Evaluation

Perform baseline spirometry before and after bronchodilator administration to establish normal lung function and exclude underlying asthma, COPD, or restrictive disease. 1, 2

• Conduct a focused physical examination looking specifically for obesity, skeletal defects (pectus excavatum), diaphragmatic dysfunction, or signs of restrictive lung disease 1
• Self-reported symptoms and therapeutic trials without objective testing are not diagnostic and should never be used alone 1, 2

Bronchoprovocation Challenge Testing

If spirometry is normal, proceed with standardized exercise challenge or surrogate hyperosmolar testing (EVH or mannitol). 1

Exercise Challenge Protocol:

• Use treadmill or cycle ergometry with the patient achieving and sustaining heart rate ≥85% of maximum in adults (≥95% in children and elite athletes) for 6 minutes after a 2-4 minute warm-up 1, 2
• Measure spirometry at baseline, immediately post-exercise, and at 5,10, and 15-minute intervals to detect delayed bronchoconstriction 2
• A positive test shows ≥10% fall in FEV1 from baseline 1

Surrogate Challenge Options:

• EVH (eucapnic voluntary hyperpnea) is the preferred surrogate challenge for competitive athletes without current asthma 1
• Mannitol challenge is preferable for safety reasons in patients with known asthma 1
• If a graded challenge (mannitol) is negative but EIB is still suspected, consider an ungraded challenge (exercise or EVH) 1

Critical Differential Diagnoses

Distinguish EIB from exercise-induced laryngeal dysfunction (EILD) by identifying inspiratory stridor versus expiratory wheezing; flexible laryngoscopy during exercise confirms EILD. 1

• Perform cardiopulmonary exercise testing (CPET) if symptoms persist despite negative challenge testing, particularly in children and adolescents, to identify dysfunctional breathing, hyperventilation, or deconditioning 1, 2
• Consider exercise-induced anaphylaxis if respiratory symptoms are accompanied by pruritus, urticaria, or hypotension 1
• Refer for cardiology evaluation when breathlessness occurs with chest pain or cardiac risk factors are present 1, 2

Treatment Strategy

First-Line Pharmacotherapy

Prescribe inhaled short-acting β2-agonists (SABAs) 15 minutes before exercise for both protection and accelerated recovery of lung function. 1

• SABAs provide bronchodilation and bronchoprotection with strong evidence (Evidence Level A) 1
• A single dose of SABA, LABA, or both on an intermittent basis (<4 times per week) before exercise protects against or attenuates EIB 1
• Critical caveat: Daily use of β2-agonists (alone or with ICS) causes tolerance, reducing duration and magnitude of protection and prolonging recovery time 1

Anti-Inflammatory Therapy

Add daily inhaled corticosteroids (ICS) when EIB occurs in patients with underlying asthma or when symptoms indicate inadequate asthma control. 1

• ICS therapy addresses the underlying airway inflammation involving mast cells and eosinophils 1, 3
• Do not use combination ICS/LABA therapy in patients with normal or near-normal baseline lung function (FEV1 >80% predicted) due to tolerance development 1

Alternative Daily Therapy

Consider daily leukotriene receptor antagonists (LTRAs) as they do not cause tolerance and attenuate EIB in approximately 50% of patients. 1

• Montelukast 10 mg once daily can be used for intermittent or maintenance prophylaxis 1, 4
• LTRAs provide incomplete protection and are not effective for reversing acute airway obstruction 1
• For prevention of EIB specifically, a single dose should be taken at least 2 hours before exercise; do not take additional doses within 24 hours 4
• Patients already taking daily montelukast for asthma should not take an additional dose for EIB prevention 4

Mast Cell Stabilizers

Consider inhaled cromolyn sodium 15 minutes before exercise as it attenuates EIB without bronchodilator activity, though it has short duration of action. 1

• Nedocromil sodium is currently unavailable in the United States 1
• Can be used alone or as adjunctive therapy 1

Non-Pharmacological Interventions

• Face masks promote humidification and prevent water loss, attenuating the hyperosmolar airway environment that triggers EIB 1
• Proper warm-up protocols may reduce severity 5, 6

Monitoring and Follow-Up

Schedule regular office visits because medication effectiveness varies over time due to asthma variability, environmental conditions, exercise intensity, and tachyphylaxis. 1

• Reassess patients who require daily β2-agonist use, as this suggests inadequate asthma control requiring ICS therapy 1
• Monitor for development of tolerance with regular β2-agonist use 1

Common Pitfalls to Avoid

• Never diagnose EIB based solely on patient-reported symptoms—objective testing is mandatory 1, 2
• Avoid initiating therapeutic trials without establishing a diagnosis, as this leads to unnecessary medication use and missed alternative diagnoses 2
• Do not prescribe daily LABA therapy in patients with normal baseline lung function due to tolerance and reduced efficacy 1
• Recognize that daily chronic treatment for asthma has not been established to prevent acute episodes of EIB—pre-exercise prophylaxis remains necessary 4