“I Can’t Breathe When I Run” David A. Schaeffer, M.D. Chief, Division of Pulmonology/Allergy & Immunology NCC- Jacksonville Assistant Professor of Pediatrics Mayo Medical School Medical Director of Pulmonary Care and Community Asthma Program, Wolfson Children’s Hospital

Definition of Asthma A chronic inflammatory disorder of the airways Many cells and cellular elements play a role Chronic inflammation is associated with airway hyperresponsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness, and coughing Widespread, variable, and often reversible airflow limitation A chronic inflammatory disorder of the airways Many cells and cellular elements play a role Chronic inflammation is associated with airway hyperresponsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness, and coughing Widespread, variable, and often reversible airflow limitation © Global Initiative for Asthma

Diagnosing Asthma Troublesome cough, particularly at night Awakened by coughing Coughing or wheezing after physical activity Breathing problems during particular seasons Coughing, wheezing, or chest tightness after allergen exposure Colds that last more than 10 days Relief when medication is used

What Is Exercise-Induced Asthma EIA or Exercise-induced bronchospasm Transient airflow obstruction associated with physical exertion

Prevalence of EIA General population % Asthmatics 90 % Allergic rhinitis 40 %

EIA Symptoms Dyspnea Cough Wheezing Chest tightness Chest pain Onset 5 to 10 minutes after exercise begins Peaks 5 to 10 minutes after exercise stops Resolves after minutes

EIA: Effect of Exercise Intensity and Thermal Environment Ref: McFadden et al. NEJM 1994;330:

Changes in Pulmonary Mechanics During and After Exercise Ref: McFadden et al. NEJM 1994;330: yo, biked 4 min C, FEV 1 76 to 90 % with exercise. Post exercise FEV 1 to 41 % Beta agonist, 92 to 102 % with exercise. Post exercise FEV 1 by 14 % Control Beta agonist B 0 min FEV1FEV1

Pathogenesis of EIB Airway inflammation Epithelial injury Inflammatory mediators Cellular influx into the airways Sensory nerve activation Water movement and/or thermal gradients

Pathophysiology of EIA Postexertional airway rewarming –airway cooling during rapid breathing –rapid reheating when rapid breathing stops

How Intra-airway Thermal Fluxes Cause EIA Water loss hypothesis: Humidity Evaporation mucosal surface water Osmolarity Mast cell degranulation Airway rewarming hypothesis: Heat loss Decreased bronchial blood flow Post exercise Reactive hyperemia Edema

Differential Diagnosis of EIA Poor physical fitness Occult cardiac or pulmonary disease Vocal cord dysfunction Exercise- induced hyperventilation

Vocal Cord Dysfunction: AKA Intractable asthma Laryngeal dyskinesia Factitious asthma / Pseudoasthma Psychogenic asthma or stridor Emotional laryngeal wheezing Nonorganic acute upper airway obstruction

VCD: Adduction of vocal cords Ref: Landwehr et al. Pediatrics 1996;98:971-4.

VCD: Intractable or Factitious Asthma Lack of improvement in sxs despite aggressive rx Difficulty breathing shortly after onset of exercise Complaint of “difficulty getting air in” or “throat closing off” Lack of cough with exercise Begins suddenly and resolves quickly when exercise stops

Diagnosis of VCD History PE –inspiratory wheezing over larynx –pts can breath hold, cough, and pant –sxs improve with distraction PFTs –blunting of inspiratory flow-volume loop Improves with: –nasal breathing, CPAP, IPPB, sedation Flexible bronchoscopy

Exercise-induced Hyperventilation Reported in 11/32 children with atypical asthma who had an exercise test –c/o chest tightness, NO wheeze/cough/ FEV 1 Significant decrease in end-tidal pCO 2 –23 vs 10 mmHg Inappropriate vs compensatory hyperventilation –exercise limitation beyond anaerobic threshold Ref: Hammo and Weinberger. Ann All Asthma Imm 1999;82:574-8

EIA Refractory Period Exercise induces tachyphylaxis Refractory period lasts ~ 40 minutes Warm up 15 to 30 minutes followed by 15 minute rest

Diagnosis of EIA: Clinical Clinical history of sxs –type & level of exercise –timing of onset of sxs –describe sxs Response to trial of inhaled BD

Diagnosis of EIA: PFTs Pulmonary function testing –Peak flow rates 25 % change –Spirometry pre and post- bronchodilator FEV 1 10 % change Exercise challenge testing

Diagnosis of EIA-Exercise Challenge Isocapnic hyperventilation Exercise for 6 to 8 minutes –free running –treadmill –cycle ergometer –80 % max O2 consumption or HR 170 bpm

Determinants of EIA Severity Underlying asthma severity Duration, Intensity, & Type of exercise Environmental conditions –cold > warm dry > humid –air pollutants Interval since last exercise

Effects of Drug Rx for EIA

Treatment of EIA-Non Pharmacologic Warm-up Exercise choice

EIA- Low Asthmogenic Exercise Low ventilation –tennis, hand/rcqball –gymnastics, karate –sprinting –football, baseball –golf –boxing, wrestling –skiing Warm & Humid –swimming –diving

EIA- High Asthmogenic Exercise High ventilation –Running long distance –Bike riding –Basketball –Soccer Cool & dry –Ice hockey –Ice skating –Cross country skiing