10/9/24, 11:43 Asthm
AM a
ASTHMA
This module will enable students to:
1. Describe the current Canadian trends in the prevalence of asthma.
2. Describe the etiology of asthma.
3. Describe the pathophysiology of asthma.
4. Link the pathogenesis of asthma to the clinical manifestations and
evaluation of the disease.
5. Provide scientific rationale for interventions.
6. Provide scientific rationale for patient teaching.
CONCEPTS IN ACTION – ASTHMA
- The respiratory system is composed of the airway passages, the
lungs, and the associated blood vessels
- The purpose of the respiratory system is to provide for oxygen and carbon dioxide
exchange between air and blood
Respiration consists of 3 distinct processes
1. Ventilation: is the movement of air from the
- Air must be taken in through the upper airway passages comprising the
- The air then proceeds from there into the lower airway consisting of
the trachea, the bronchi, and the bronchioles of the lungs
- the process of taking air in is called inspiration
2. Perfusion:
3. Diffusion:
- Diffusion is the movement of gasses between the roughly 1 million alveoli
or air-filled sacs within the lungs and the capillaries that supply the alveoli
- In diffusion, gasses move across the
- Oxygen moves from the air that is in the alveoli into the blood flowing
through the pulmonary capillaries
-
- Completing the respiration process, the carbon dioxide is expelled through expiration
-
-
about:bl 1/
,10/9/24, 11:43 Asthm
AM a
Asthma
- involves
- Asthma can be characterized as extrinsic or intrinsic based on the factors
that trigger the disorder
Extrinsic atopic asthma: initiated by a type one hypersensitivity response to an extrinsic antigen
- An antigen binds with a mast cell and causes mast cell degranulation with
release of histamine, leukotrienes, interleukins and prostaglandins
resulting in inflammation and bronchospasms
- The airway inflammation in turn produces airway edema, epithelial injury,
and impaired mucociliary function
Intrinsic non-apotic asthma: is initiated by diverse non-immune mechanisms
- However many people have overlapping mechanisms
- Intrinsic asthma is triggered by irritant receptors and vagal reflex
- It is often triggered by viral infections, inhaled irritants, NSAIDS, sulfites,
and emotional stress
- Asthma usually has its onset in childhood or adolescence
- However adults may develop asthma without a previous history of disease
Asthma
- Arises from a complex interaction between heredity and environmental
factors and manifests as acute attacks
- The early phase or acute response of asthma occurs within 10 to 20
minutes of exposure to a trigger
- Mast cells, which in people with asthma or in a pre-sensitized state, react
to antigens and release histamine, leukotrienes, interleukins, and
prostaglandins
- With airborne antigens the antigen binds to the mast cells on the mucosal surface of the
airway
- The release of inflammatory mediators leads to infiltration of
inflammatory cells that allows the antigens to reach the submucosal
mast cells
- Additionally, direct stimulation of parasympathetic receptors causes bronchospasm, and
increased vascular permeability causes mucosal edema and
increased mucus secretions
- As airway obstruction progresses, expiration becomes prolonged
- Late phase response develops four to eight hours after exposure to an asthmatic trigger
- Release of inflammatory mediators induces the migration and
activation of other inflammatory cells
- Basophils, eosinophils, and neutrophils
- The late phase response involves inflammation, increased airway
responsiveness, and renewed bronchospasm
about:bl 2/
, 10/9/24, 11:43 Asthm
AM a
- These symptoms lead to further airflow limitation and continued
heightened airway responsiveness
- This sequence prolongs the asthma attacks and sets into motion a vicious cycle of
exacerbations including additional edema, epithelial injury and impaired
mucociliary function
- Treatment for all asthma patients is approached in 2 ways:
- Control of factors contributing to asthma severity
- Pharmacologic treatment
- If exposure to triggers can’t be avoided then pharmacologic treatment is usually needed
- Corticosteroids, bronchodilators, mast cell stabilizers, beta
agonists, and anticholinergic drugs
- Asthma is a chronic reactive airway disorder characterized by increased resistance to
airflow due to obstruction of the airway passages
- Asthma involves a hypersensitivity reaction to stimuli and the release of
chemical mediators from pre-sensitized mast cells, leading to a vicious
cycle of edema, epithelial injury and impaired mucociliary function
PREVALENCE OF ASTHMA
- Asthma is the most common
chronic disease among children and it
remains a major cause of hospitalization
- In children, the prevalence is highest
amongst boys, while in adults it is highest
amongst women
- First nations, inuit, and metis
communities experience a much higher
prevalence of asthma than the general
population
- The most recent data from the
canadian chronic disease indicates that
age-standardized asthma prevalence are
highest in ontario and nova scotia, with the
lowest proportions in the northwest
territories, yukon, and nunavut
- In ontario, the incidence of
asthma has slowly declined overtime,
while the prevalence continues to
increase owing to the fact more
people are living with asthma and the rate of mortalities related to asthma are declining
- This is consistent with other developed nations
- Globally, asthma-related death occurs most in low- and lower-middle
income countries where under-diagnosis and under-treatment still remain
a challenge
- Although asthma continues to be a major cause of hospitalization for
children in canada, hospitalization for children in canada, hospitalization
rates have decreased in children + adults along with ER visits
- This is attributed to appropriate use of asthma practice guidelines
and active involvement of patients and their families
about:bl 3/
AM a
ASTHMA
This module will enable students to:
1. Describe the current Canadian trends in the prevalence of asthma.
2. Describe the etiology of asthma.
3. Describe the pathophysiology of asthma.
4. Link the pathogenesis of asthma to the clinical manifestations and
evaluation of the disease.
5. Provide scientific rationale for interventions.
6. Provide scientific rationale for patient teaching.
CONCEPTS IN ACTION – ASTHMA
- The respiratory system is composed of the airway passages, the
lungs, and the associated blood vessels
- The purpose of the respiratory system is to provide for oxygen and carbon dioxide
exchange between air and blood
Respiration consists of 3 distinct processes
1. Ventilation: is the movement of air from the
- Air must be taken in through the upper airway passages comprising the
- The air then proceeds from there into the lower airway consisting of
the trachea, the bronchi, and the bronchioles of the lungs
- the process of taking air in is called inspiration
2. Perfusion:
3. Diffusion:
- Diffusion is the movement of gasses between the roughly 1 million alveoli
or air-filled sacs within the lungs and the capillaries that supply the alveoli
- In diffusion, gasses move across the
- Oxygen moves from the air that is in the alveoli into the blood flowing
through the pulmonary capillaries
-
- Completing the respiration process, the carbon dioxide is expelled through expiration
-
-
about:bl 1/
,10/9/24, 11:43 Asthm
AM a
Asthma
- involves
- Asthma can be characterized as extrinsic or intrinsic based on the factors
that trigger the disorder
Extrinsic atopic asthma: initiated by a type one hypersensitivity response to an extrinsic antigen
- An antigen binds with a mast cell and causes mast cell degranulation with
release of histamine, leukotrienes, interleukins and prostaglandins
resulting in inflammation and bronchospasms
- The airway inflammation in turn produces airway edema, epithelial injury,
and impaired mucociliary function
Intrinsic non-apotic asthma: is initiated by diverse non-immune mechanisms
- However many people have overlapping mechanisms
- Intrinsic asthma is triggered by irritant receptors and vagal reflex
- It is often triggered by viral infections, inhaled irritants, NSAIDS, sulfites,
and emotional stress
- Asthma usually has its onset in childhood or adolescence
- However adults may develop asthma without a previous history of disease
Asthma
- Arises from a complex interaction between heredity and environmental
factors and manifests as acute attacks
- The early phase or acute response of asthma occurs within 10 to 20
minutes of exposure to a trigger
- Mast cells, which in people with asthma or in a pre-sensitized state, react
to antigens and release histamine, leukotrienes, interleukins, and
prostaglandins
- With airborne antigens the antigen binds to the mast cells on the mucosal surface of the
airway
- The release of inflammatory mediators leads to infiltration of
inflammatory cells that allows the antigens to reach the submucosal
mast cells
- Additionally, direct stimulation of parasympathetic receptors causes bronchospasm, and
increased vascular permeability causes mucosal edema and
increased mucus secretions
- As airway obstruction progresses, expiration becomes prolonged
- Late phase response develops four to eight hours after exposure to an asthmatic trigger
- Release of inflammatory mediators induces the migration and
activation of other inflammatory cells
- Basophils, eosinophils, and neutrophils
- The late phase response involves inflammation, increased airway
responsiveness, and renewed bronchospasm
about:bl 2/
, 10/9/24, 11:43 Asthm
AM a
- These symptoms lead to further airflow limitation and continued
heightened airway responsiveness
- This sequence prolongs the asthma attacks and sets into motion a vicious cycle of
exacerbations including additional edema, epithelial injury and impaired
mucociliary function
- Treatment for all asthma patients is approached in 2 ways:
- Control of factors contributing to asthma severity
- Pharmacologic treatment
- If exposure to triggers can’t be avoided then pharmacologic treatment is usually needed
- Corticosteroids, bronchodilators, mast cell stabilizers, beta
agonists, and anticholinergic drugs
- Asthma is a chronic reactive airway disorder characterized by increased resistance to
airflow due to obstruction of the airway passages
- Asthma involves a hypersensitivity reaction to stimuli and the release of
chemical mediators from pre-sensitized mast cells, leading to a vicious
cycle of edema, epithelial injury and impaired mucociliary function
PREVALENCE OF ASTHMA
- Asthma is the most common
chronic disease among children and it
remains a major cause of hospitalization
- In children, the prevalence is highest
amongst boys, while in adults it is highest
amongst women
- First nations, inuit, and metis
communities experience a much higher
prevalence of asthma than the general
population
- The most recent data from the
canadian chronic disease indicates that
age-standardized asthma prevalence are
highest in ontario and nova scotia, with the
lowest proportions in the northwest
territories, yukon, and nunavut
- In ontario, the incidence of
asthma has slowly declined overtime,
while the prevalence continues to
increase owing to the fact more
people are living with asthma and the rate of mortalities related to asthma are declining
- This is consistent with other developed nations
- Globally, asthma-related death occurs most in low- and lower-middle
income countries where under-diagnosis and under-treatment still remain
a challenge
- Although asthma continues to be a major cause of hospitalization for
children in canada, hospitalization for children in canada, hospitalization
rates have decreased in children + adults along with ER visits
- This is attributed to appropriate use of asthma practice guidelines
and active involvement of patients and their families
about:bl 3/
