“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 AsthmaDefinition 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 6 - 13 %

• 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 30-60

minutes

EIA: Effect of Exercise Intensity and Thermal Environment

Ref: McFadden et al. NEJM 1994;330:1162-1167.

Changes in Pulmonary Mechanics During and After Exercise

Ref: McFadden et al. NEJM 1994;330:1162-1167.

16 yo, biked 4 min

C, FEV1 76 to 90 %with exercise. Post exercise FEV1 to 41 %

Beta agonist, 92 to 102 %with exercise.Post exercise FEV1

by 14 %

Control

Beta agonist

B 0 min 30 60

FEV1

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/ FEV1

• Significant decrease in end-tidal pCO2

– 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 • FEV1 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 EIADrug Dose Time of

Rx (min)Eff ective- ness

Durationof eff ect

Albuterol 2 p 10- 15 +++ 2- 2.5hrs

Cromalyn 2 p 10- 15 ++ 1.5- 2hrs

Salmeterol 2p/1d 15- 30 +++ 10- 12hrs

Leukotrienemodifiers

tabs 12- 24hrs ++ 12- 20hrs

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