exercise induced bronchospasm

1. Exercise Induced Bronchospasm W.S. Bew, MD, CAQSM CDR(FMF) MC USN

3. Objectives Review the epidemiology of Exercise Induced Bronchospasm (EIB) Understand the pathophysiology of EIB Review the treatment and prophylaxis of EIB

4. Definition Airway obstruction, and hyper responsiveness Triggered by exercise �Exercise induced asthma� as a term may be misleading as exercise is not an independent risk factor for asthma, but rather a trigger of bronchoconstriction in patients with underlying asthma. The term EIB is a more accurate reflection of pathophysiology and is the preferred term.�Exercise induced asthma� as a term may be misleading as exercise is not an independent risk factor for asthma, but rather a trigger of bronchoconstriction in patients with underlying asthma. The term EIB is a more accurate reflection of pathophysiology and is the preferred term.

5. Prevalence 7% of general population have asthma 80-95%% have EIB 15-20% general population have allergic rhinitis 40% have EIB 3-4% of the general population with neither asthma nor allergies have EIB Self selection and under treatment probably explains the differenceSelf selection and under treatment probably explains the difference

6. Pathophysiology Hyperventilation associated with exercise Cool(<70F) and Dehumidified(<50%) air Osmotic homeostasis of airway fluid layer Release of chemical mediators In non-asthmatics, exercise causes bronchodilation Rigorous exercise causes increased ventilation. In susceptible individuals. Airborne allergens and pollutants may play a role.In non-asthmatics, exercise causes bronchodilation Rigorous exercise causes increased ventilation. In susceptible individuals. Airborne allergens and pollutants may play a role.

7. Clinical Manifestations Bronchospasm begins ~3 minutes into exercise and peaks at about 10-15 min Resolves by 60 min Almost never life threatening Should not prohibit sports participation Presents with dyspnea out of proportion to the task. Except SCUBAPresents with dyspnea out of proportion to the task. Except SCUBA

8. Refractory Period 50% of those with EIA Exercise w/in 2h of EIA attack provokes a weaker response than the first Etiology not clear Degranulation of mast cells Release of Bronchodilating prostaglandin Increased sympathetic toneDegranulation of mast cells Release of Bronchodilating prostaglandin Increased sympathetic tone

9. Late Phase Response 4-8 hours after first attack Occurs 50% of children and 40% of adults Usually follows a severe early response Inflammatory Inflammation in small airways.Inflammation in small airways.

10. Differential Dx Asthma URI Pneumonia COPD Cardiac Dz Pulmonary Embolus GERD Anaphylaxis

11. Diagnosis History Physical Lab Testing

12. History Cough, dyspnea, chest tightness Children: Chest pain and poor exercise tolerance Many athletes assume they are in poor physical condition Sx associated with exercise out of proportion to the performed taskSx associated with exercise out of proportion to the performed task

13. Physical When not exercising: usually normal During attack: Increased RR Prolonged expiratory phase Decreased breath sounds Wheezing Severe attacks are rare.Severe attacks are rare.

14. Laboratory Testing Spirometry FEV1 PEFR Challenge testing Compare pre and post exercise spirometry In patients with well-established Dx of asthma who have EIB, lab testing not necessary unless Sx do not respond to beta agonists Forced exp flow volume in 1 sec. Ratio fev1/forced vital calacaty: FVC will show a proportionally smaller reduction with RAD Peak exp flow rate Exercise challenge most specific for EIA. In patients with well-established Dx of asthma who have EIB, lab testing not necessary unless Sx do not respond to beta agonists Forced exp flow volume in 1 sec. Ratio fev1/forced vital calacaty: FVC will show a proportionally smaller reduction with RAD Peak exp flow rate Exercise challenge most specific for EIA.

15. Laboratory Testing Protocol Discontinue asthma meds No exercise 12h before test Check pretest spirometry Exercise: 5-8 min at 80%VO2max or 85%max HR Post exercise spirometry (0, 5, 10, 15, 20, & 30min) Treadmill or stationary bicycleTreadmill or stationary bicycle

16. Laboratory Testing EIB Diagnosis 10% or greater decrease in FEV1 EIB Severity (FEV1) Mild: 10%-25% decrease Moderate: 25%-40% decrease Severe: >40% decrease PEFR response do not correlate to Dx process well and are not recommended to follow this process.PEFR response do not correlate to Dx process well and are not recommended to follow this process.

17. Management Patient Education Environmental control Pharmacological therapy Major goal in education is to ensure that exercise is NOT avoided by patients with EIB. Improved aerobic fitness leads to reduced minute ventilation with exercise, less cool dry air to lungs. Ensure that Asthma/Allergies under good control Signs/Sx, triggers, how to use medications/inhalers, nose breathing, slow deep breathing Exercise ~30 min prior to event to induce refractory period Tough to do: Swimming a good choice for mod or severeMajor goal in education is to ensure that exercise is NOT avoided by patients with EIB. Improved aerobic fitness leads to reduced minute ventilation with exercise, less cool dry air to lungs. Ensure that Asthma/Allergies under good control Signs/Sx, triggers, how to use medications/inhalers, nose breathing, slow deep breathing Exercise ~30 min prior to event to induce refractory period Tough to do: Swimming a good choice for mod or severe

18. Medications for Asthma Rescue (Bronchodilators) Short-acting beta agonists Anticholinergics Maintenance Long acting beta agonists Anti-inflammatory meds Glocorticoids Khellin derivatives Leukotriene antagonists A Review Atropine used if inadequate response to alb alone (better for COPD) Khellin derivatives: Cromolyn & NedocramilA Review Atropine used if inadequate response to alb alone (better for COPD) Khellin derivatives: Cromolyn & Nedocramil

19. Prevention Warm up before activity At least 15 min Beta Agonists: 90% effective Short acting Use 10-15 min before exercise Lasts 1-2 hrs Long acting Use 1 hr before exercise Lasts 12 hrs B agonists bronchodilate and appear to stabilize mast cells The primary treatment for EIB Can also be used to treat EIB Sx. Resistance can develop with prolonged usage B agonists bronchodilate and appear to stabilize mast cells The primary treatment for EIB Can also be used to treat EIB Sx. Resistance can develop with prolonged usage

20. Prevention Khellin derivatives: 70% effective Use 15-45 min before exercise Lasts 2 hrs Anticholinergics Not been shown conclusively to prevent EIB May be helpful if unable to tolerate beta agonists No tachyphyllaxis (resistance)No tachyphyllaxis (resistance)

21. Prevention Antileukotriene agents For chronic asthma with EIB Appears to be as effective as beta agonists Effects last up to 12 hours No tachyphyllaxis Will not relieve wheezing like beta agonists do.No tachyphyllaxis Will not relieve wheezing like beta agonists do.

22. Banned Substances Beta Agonists: considered a stimulant May use inhaled only Written justification by physician WADA: http://www.wada-ama.org/ NCAA: http://www.ncaa.org/wps/portal/ncaahome?WCM_GLOBAL_CONTEXT=/ncaa/NCAA/Legislation%20and%20Governance/Eligibility%20and%20Recruiting/Drug%20Testing/drug_testing.html Athletes will need to file a Therapeutic Use Exception PRIOR to elite competionsAthletes will need to file a Therapeutic Use Exception PRIOR to elite competions