“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
© Global Initiative for Asthma
Diagnosing Asthma
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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
16 yo, biked 4 min
C, FEV1 76 to 90 %
with exercise.
Post exercise FEV1
to 41 %
Beta agonist
F
E
V1
Beta agonist, 92 to 102 %
with exercise.
Post exercise FEV1
by 14 %
Control
B 0 min
30
60
Ref: McFadden et al. NEJM 1994;330:1162-1167.
Pathogenesis of EIB
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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
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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
Drug
Dose
Albuterol
2 p
Time of
Rx (min)
10-15
Effective Duration
-ness
of effect
2-2.5hrs
Cromalyn
2 p
10-15
++
1.5-2hrs
Salmeterol
2p/1d
15-30
+++
10-12hrs
12-24hrs
++
12-20hrs
Leukotriene tabs
modifiers
+++
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
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Running long distance
Bike riding
Basketball
Soccer
• Cool & dry
– Ice hockey
– Ice skating
– Cross country
skiing