Asthma Flashcards
What is asthma?
a disease characterized by recurrent attacks of breathlessness and wheezing which vary in severity and frequency from person to person
- asthma affects all age groups but usually starts in childhood
What causes asthma?
due to inflammation of the air passages in the lungs and affects the sensitivity of the nerve endings in the airways so they become easily irritated
- in an attack the lining of the passages swell causing the airways to narrow and reducing the flow of air in and out of the lungs
Epidemiology?
- Affects around 300 million people worldwide
- Half of patients with childhood asthma will not continue to have symptoms in adulthood (”grow out of it”)
- Prevalence in Africa: 13% (and rising), Malawi: unknown
- But according to WHO: 3 people die each day in Malawi from asthma
> Underdiagnosed and underrecognized.
> Most recorded deaths are in adults >45 years
Pathogenesis?
- Airflow limitation/obstruction
- Airway hyperresponsiveness
- Inflammation of the bronchi
- Airway wall remodelling; &
epithelial damage
Pathogenesis of airflow obstruction in acute asthma?
- Bronchoconstriction
- Airway edema
- Mucous plugs (take weeks to resolve)
- Hyperinflation
Airflow obstrction in chronic asthma?
- Chronic mucous plugging, & long standing inflammation → airway remodeling with excess narrowing
- Epithelial damage → more susceptible to infection and allergens.
Airway hyperresponsiveness?
Airway response to exogenous and endogenous stimuli
1. Exogenous are direct stimulation (allergens etc)
2. Endogenous include activator substances secreted from mast cells and sensory neurons
Asthmatic attack triggers?
- exercise
- pollen
- bugs in the home
- chemical fumes
- cold air
- fungus spores
- dust
- smoke
- strong odors
- pollution
- anger/stress
- pets
- medication e.g. NSAIDS, beta blockers
- viral infections
- GERD
Etiology of asthma?
- Extrinsic (atopy) vs intrinsic (no identified causative agent).
- Atopy
- asthma, eczema, allergy
Ig E-antibody production is influenced by genetic and environmental factors. - Hygiene theory
- exposure to bacteria/viruses/fungi in childhood directs the immune and inflammatory response away from the allergic pathways (uncertain)
Symptoms of asthma?
classic triad
1. breathlessness
2. cough
3. wheeze (sometimes only nightly cough)
Important history questions?
- Symptoms & Severity
- Previous hospitalizations (frequency, last)
- Medication history
- What do they take? How is adherence?
- Exposures > allergens (“triggers”), smoking, method of cooking
- Clues to other possible etiologies
- Infectious symptoms, TB contacts, weight loss, etc.
Physical exam in asthma?
- VITALS (count the RR)
- Wheezing
- Differential diagnosis, target your physical exam to exclude other pathologies
- Inspiratory or expiratory? - Signs of atopy
Note: Approach depends on the severity (ABCD in severe exacerbation)
Ddx for wheezing?
- heart failure
- vocal cord dysfunction
- viral infections in children
- tracheal lesions
- foreign body aspiration
Note:
- In mild asthma may only be expiratory
- in more moderate severe inspiratory and expiratory
- In very severe, lungs may be too clamped down to have any wheezing
Signs of atopy?
- Allergic shiners
- transverse crease on nose from allergic rhinitis
- atopic dermatitis (eczema; 25% has Dennie Morgan lines)
- Nasal crease: caused by re[eated nose rubbing (allergic rhinitis)
Clinical diagnosis of asthma?
- history taking
- physical examination
- trial of bronchodilators