Exercise-Induced Asthma

1. See Also
   1. Asthma
   2. Exercise-Induced Anaphylaxis
   3. Exercise-Induced Urticaria
2. Pathophysiology
   1. Hyperventilation of dry, cool air
   2. Loss of heat or water from lungs during Exercise
3. Epidemiology
   1. Occurs in 90% of Asthmatics
   2. May occur in as many as 29% of athletes
      1. Cold weather athletes appear more susceptible
      2. Occurs in 50% of olympic cross country skiers
4. Symptoms
   1. Timing
      1. Onset during or after Exercise
      2. Does not usually affect first 5 minutes of Exercise
      3. Symptom duration of 5 minutes or longer
   2. Exercise-related symptoms
      1. Shortness of Breath
      2. Wheezing
      3. Decreased Exercise endurance
      4. Chest tightness
      5. Cough
      6. Epigastric Pain
      7. Pharyngitis
5. Signs
   1. Cardiopulmonary exam normal at rest
   2. Exclude associated conditions (see differential diagnosis below)
6. Differential Diagnosis
   1. Cardiovascular disorder
      1. Congestive Heart Failure
      2. Coronary Artery Disease
      3. Arrhythmia
      4. Hypertrophic Cardiomyopathy
      5. Heart Valve disorders
      6. Pulmonary AV malformation
   2. Lung disorder
      1. Chronic Asthma
      2. Chronic Obstructive Pulmonary Disease (COPD)
      3. Cystic Fibrosis
      4. Interstitial Lung Disease
      5. Pectus Excavatum
      6. Scoliosis
      7. Tracheobronchial malacia
   3. Head and neck disorders
      1. Chronic Sinusitis
      2. Allergic Rhinitis
      3. Nasal Polyps
      4. Septal deviation
      5. Vocal Cord Dysfunction
   4. Miscellaneous disorders
      1. Deconditioning or Obesity
      2. Myopathy
      3. Anxiety Disorder or Hyperventilation
7. Diagnostics
   1. Obtain FEV1 or Peak Flow at rest (exclude Asthma)
   2. Exercise challenge with Pulmonary Function Testing
      1. Not required for classic presentation
      2. Most patients may be treated empirically
8. Management: General Measures
   1. Maintain regular Exercise for physical conditioning
   2. Warm up and cool down for 10 minutes before and after
   3. Exercise in humidified, warm environment
   4. Cover nose and mouth during cold weather Exercise
      1. Consider heat exchange mask (available at sporting good stores)
   5. Avoid Exercise within 2 hours following a meal
   6. Avoid Exercise in high allergen, ozone or pollution
9. Management: Medications
   1. Treat related conditions
      1. Asthma
      2. Allergic Rhinitis
   2. Primary Agents
      1. Short-acting Beta Agonist (Albuterol, Pirbuterol)
         1. Use 2 puffs, 15-30 minutes before Exercise
   3. Secondary Adjunctive Agents
      1. Step 1: Leukotriene Modifiers (preferred if comorbid Allergic Rhinitis)
         1. Taken on regular schedule
         2. Montelukast (Singulair)
         3. Zafirlukast (Accolate)
         4. Zileuton XR (Zyflo CR)
      2. Step 2: Mast Cell Stabilizer 15 minutes before Exercise
         1. Consider using on regular schedule 2-4 times daily
         2. Cromolyn (Intal)
         3. Nedocromil (Tilade)
      3. Step 3: Inhaled Corticosteroid trial (preferred in underlying Asthma)
         1. Obtain initial Exercise challenge with PFTs
         2. Inhaled Corticosteroid (e.g. Qvar, Pulmicort, Flovent, Asmanex) for 4 weeks
         3. Obtain follow-up Exercise challenge with PFTs
         4. Continue Inhaled Corticosteroid if benefit seen
         5. Consider in combination with inhaled Long-acting Beta Agonist (e.g. Advair)
      4. Step 4: Ipratropium Bromide (Atrovent)
         1. Inhaled 2 puffs up to qid
      5. Other interventions with unproven benefit
         1. Vitamin C 2 grams before Exercise
         2. Dietary salt reduction
         3. Omega 3 Fatty Acid supplementation
10. Guidelines: Sporting organization rules regarding restricted medications for Asthma
    1. Organizations
       1. United States Olympic Committee (USOC)
       2. National Collegiate Athletic Association (NCAA)
    2. No approval needed
       1. Ipratropium Bromide
       2. Leukotriene Modifiers
          1. Montelukast (Singulair)
          2. Zafirlukast (Accolate)
       3. Theophylline
       4. Mast Cell Stabilizers
          1. Cromolyn (Intal)
          2. Nedocromil (Tilade)
    3. Prior approval required
       1. Inhaled Corticosteroids (requires declaration of use by USOC)
       2. Inhaled Beta Agonist (permitted only with prescription by NCAA, USOC)
          1. Albuterol (Proventil, Ventolin)
          2. Pirbuterol (Maxair)
          3. Terbutaline (Brethine)
          4. Salmeterol (Serevent)
    4. Prohibited
       1. Oral (not inhaled) beta 2 agonists
11. References
    1. Krafczyk (2011) Am Fam Physician 84(11): 427-34
    2. Sinha (2003) Am Fam Physician 67(4):769-74
    3. Tan (2002) Ann Allergy Asthma Immunol 89:226-35
    4. Tan (1998) Sports Med 25:4