“I Can’t Breathe When I Run” David A. Schaeffer, M.D. Chief, Division of Pulmonology/Allergy &...
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Transcript of “I Can’t Breathe When I Run” David A. Schaeffer, M.D. Chief, Division of Pulmonology/Allergy &...
“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
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: 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
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