SEARCH RESULTS FOR: Pediatric-Asthma-Exacerbations

Pediatric Asthma Exacerbations

Pediatric Asthma Exacerbations: Pathogenesis and clinical findings
Non-allergic asthma (not triggered by allergens)
Allergic asthma (triggered by allergens)
(e.g., pollen, animal dander, dust mites)
Viral respiratory
tract infections
Extreme weather Physical exertion Pollutants (e.g.
cigarette smoke)
Allergen inhalation
activates IgE on mast cells
Virus invades epithelial
cells in airway
Inhalation of cold
↑ Minute ventilation
or dry air dries
↑ Air flow irritates & dries airway mucosa
airway mucosa Inhaled irritants
damage airway
Epithelial barrier breakdown
releases inflammatory mediators
epithelium & activate
immune cells
Immune system releases inflammatory mediators (e.g., histamine, leukotrienes, prostaglandins, cytokines) into airway
Histamine & leukotrienes stimulate smooth
muscle cells in the airway to constrict
Cytokines attract white blood cells (e.g.,
eosinophils, neutrophils, monocytes)
Inflammatory mediators
stimulate epithelial goblet cells
Inflammatory mediators ↑ vascular
permeability in airway mucosa
Bronchoconstriction
(bronchioles narrow)
Airway inflammation
persists & intensifies
Goblet cells produce excess mucus
plugs & obstruct small airways
Airway wall swells
(mucosal edema)
Asthma Exacerbation
Acute or sub-acute episode marked by a progressive ↑ in asthma symptoms & a measurable ↓ in lung function compared to patient’s baseline
Bronchial hyperresponsiveness (an exaggerated & easily
triggered constricting response of the airways to various stimuli)
Narrowed bronchioles mechanically
obstructs air flow & ↓ ventilation
↓ Ventilation impairs
elimination of carbon
dioxide (CO₂) from blood
More force is
required to
expel air
Turbulent airflow through
narrowed bronchioles
during expiration
Severe airflow obstruction
prevents airflow into distal
lung regions
↓ Ventilation
traps air in
alveoli
Prolonged
expiratory phase
Inflammatory
mediators & mucous
hypersecretion
sensitize afferent
nerves in airway
↑ Arterial partial
pressure of CO2 (PaCO2))
triggers hyperventilation
↑ Work of
breathing
Expiratory
wheeze
↓ Breath
sounds
Afferents activate
cough reflex via
Trapped air ↑ intra-
Air trapping
alveolar pressure
overinflates
vagus nerve
above pleural pressure
lungs
Cough
↓ PaCO2
↑ blood
pH
Tachypnea
(↑ respiratory
rate)
Exhaustion of
respiratory muscles
↓ strength &
respiratory rate
Air trapping limits oxygen
(O2) exchange in alveoli
↑ Pressure
ruptures alveoli
↓ Diaphragmatic
excursion
Hyperinflation
on chest X-ray
Pneumothorax (air collects in pleural space)
↓ Oxygenation of
blood (hypoxemia)
Respiratory
alkalosis
Normocapnia,
can progress
to hypercapnia
(↑ PaCO2)
Engagement
of accessory
respiratory
muscles
Respiratory
failure
↓ O2 delivery to
peripheral tissues
Legend: Authors:
Fares Senjar, Jody Platt
Hypoxemic hypoxia (SpO2 < 90% on room air)
Reviewers:
Merry Faye Graff, Emily J. Doucette,
Central cyanosis (bluish discoloration
of skin & mucous membranes)
Elizabeth De Klerk, Yan Yu,
Alexander Arnold, Naminder Sandhu*,
Jonathan Liu*
Tachycardia (↑ heart rate)
*MD at time of publication
Complications
Published Dec 2, 2013; updated Nov 15 2025 on www.thecalgaryguide.com
Pathophysiology Mechanism
Sign/Symptom/Lab Finding