Exercise-Induced Bronchospasm Jonathan P. Parsons, MD, MSc Associate Professor of Internal Medicine Division of Pulmonary and Critical Care Medicine Associate Director, The Ohio State University Asthma Center

Learning Objectives At the end of the module, you will know the following: Be able to define exercise-induced bronchospasm (EIB) Discuss the epidemiology/public health burden of EIB Explain the pathophysiology of EIB Describe the typical clinical presentation of EIB the diagnostic challenges in patients with EIB Outline the treatment of EIB

Bronchospasm Normal smooth muscle layer Smooth muscle hypertrophy Narrow airway lumen Normal airway lumen Normal Bronchiole Bronchiole during EIB attack

Definition of EIB EIB is simply defined as airway narrowing or bronchospasm that occurs in association with exercise. EIB is specifically and objectively defined as a decline in lung function of > 10% from baseline after appropriate testing EIB can occur during exercise, but happens more commonly after an exercise session is over

Prevalence of EIB in patients with asthma Exercise is one of the most common triggers of bronchospasm in patients with chronic asthma 80-90% of patients with chronic asthma will experience EIB

Common triggers of bronchospasm in patients with asthma Parsons JP et al. Allergy Asthma Proc. 2011 Nov-Dec;32(6):431-7.

Prevalence of EIB in general population EIB also occurs in up to 10-15% of the general population without chronic asthma. These are patients whose sole trigger of bronchospasm is exercise. “but I don’t have asthma” “you can still have EIB”

Prevalence in Athletes There is a significant prevalence of EIB in athletes Studies have reported prevalence rates ranging from 10-50% depending on population studied Some studies suggest that certain sports may have higher relative risk of EIB cold weather sports (i.e. cross-country skiing) high-aerobic demand sports (i.e. soccer, distance running) sports with environmental exposures (i.e. chlorine fumes in swimming, poor air quality in ice rinks)

Burden of EIB Do you avoid physical activity due to EIB? % that answered yes Survey population: 1000 adults and 500 children with asthma Parsons JP et al. Allergy Asthma Proc. 2011 Nov-Dec;32(6):431-7.

Burden of EIB % that answered yes Parsons JP et al. Allergy Asthma Proc. 2011 Nov-Dec;32(6):431-7.

Health Limits Activities: A Lot or Some Parsons JP et al. Allergy Asthma Proc. 2011 Nov-Dec;32(6):431-7. Parsons JP et al. Allergy Asthma Proc. 2011 Nov-Dec;32(6):431-7.

Pathophysiology of EIB Elsevier, Inc.

Pathophysiology of EIB There is strong evidence that mediators from mast cells and eosinophils are released into the airways during EIB This mediator release is hypothesized to be the predominant cause of EIB

Pathophysiology of EIB

Typical clinical presentation Bronchodilation EIB (+) EIB (-) Exercise Peak bronchospasm Airflow in EIB

Presenting Symptoms of EIB Common Cough Shortness of breath Fatigue Chest tightness Wheezing More subtle Poor performance for conditioning level Avoidance of activity Symptoms in specific environments Mild impairment of performance Severe bronchospasm/risk of respiratory failure

Diagnostic challenges in EIB High index of suspicion required as symptoms can be subtle and non-specific Symptoms of EIB are frequently mistaken as normal manifestations of exercise. Many patients are very poor perceivers of symptoms of bronchospasm Competitive athletes are often stubborn Objective confirmation of suspected EIB is essential. Parsons JP et al. Med Sci Sports Exerc. 2007

Diagnosis of EIB Spirometry Commonly will be normal Normal spirometry at rest does not rule out EIB Electrocardiogram (ECG) Wolff-Parkinson-White Long QT Chamber enlargement Bronchoprovocation Testing Eucapnic Voluntary Hyperventilation (EVH) testing Exercise Challenge

Eucapnic Voluntary Hyperventilation (EVH) Preferred test to document need for bronchodilators during competition for Olympians. More sensitive and specific in some studies than other methods of bronchoprovocation. Involves breathing a 5% CO2 gas mixture 30 times per minute for 6 minutes. Increased CO2 prevents Syncope Further bronchoconstriction Anderson, SD et al. JACI. 111:45-50, 2003. Holzer, K. et al. Clin.J.Sport Med. 14:134-138, 2004. Mannix, ET et al Chest. 115:649-653, 1999.

EVH Testing At the completion of 6 minutes of hyperventilation, spirometry is performed at 3, 5, 10, 15, and 20 minute intervals after EVH. A positive response is a decline of > 10% from baseline lung function at any time-point after EVH. Anderson, S. D et. Br J Sports Med. 35:344-347, 2001.

EVH equipment

EVH test

Exercise Challenge Several studies have shown that EVH is superior to lab- or field-based exercise challenge for diagnosis of EIB However, exercise testing is widely available Probably your next best test currently available if no EVH Important to assess serial spirometry up to 20 minutes after the exercise session Mannix et al. 1999.. Chest 115(3):649-653. Holzer, K., and P. Brukner. 2004.. Clin.J.Sport Med. 14(3):134-138. Anderson et al. Med Sci Sports Exerc. 40(9):1567-1572

Treatment of EIB First-line therapy is prophylactic use of short-acting bronchodilators such as albuterol shortly before exercise. Two to four puffs taken 15 minutes before exercise provides about 4 hours of relief 80% effective

Treatment of EIB Inhaled corticosteroids are effective. daily medicine used for 4 weeks or more before effects seen Montelukast (a leukotriene modifier taken orally) also has been shown to be effective in treating EIB Must be taken 2 hours prior to exercise

Treatment of EIB Adequate warm-up prior to exercise allows athletes to often take advantage of the “refractory period.” interval in which a relative reduction in bronchospasm occurs. begins 30-90 minutes after exercise is initiated and may be due to: release of catecholamines depletion of inflammatory mediators Present in 50% of patients with EIB Unable to predict who will have refractory period or the degree of protection

Non-Pharmacologic Approaches Face mask The wearing of a face mask during activities in dry, cold air allows the air to be warmed up and humidified. Avoidance of allergen Athletes with allergies should avoid exposure to allergens as much as possible. Nutritional approach omega-3 polyunsaturated fatty acids antioxidant intake sodium restricted diet Very preliminary data

Exercise Induced Bronchospasm

Thank you! I hope that I was able to teach the subject clearly. If you have any questions, write to me: Jonathan.Parsons@osumc.edu

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