Asthma Flashcards
What is Asthma?
Astmah is a a chronic inflammatory airway disease leading to
- airway obstruction due to
- Muscle spasm (acute)
- Increased mucus production
- Inflammation/oedema (chronic)
- might lead to: fibrosis (chronic)
What is the site affected by Asthma?
Generally large airway and small airway <2 micrometers
Explain the broad pathophysiology of Asthma
Generally an inflamatory process
- trigger releases inflamatory mediators
- Activation and migration of inflamatory cells
- (Expecially Th2 cells)
- Other WBC also involved
- –> Inflamation
- Also bronchial hyperresponsiveness associated with it
What is the aetiology of asthma?
- Genetic predisposition (strong)
- Environmental exposure (hygene hypothesis)
- Air pollutans, pets, mould make it more likely, might be possible triggers
What are risk factors for developing asthma?
- Allergens (pets, dust mites, mould, tobocco smoke, pollen)
- Family history
- History of atopy (eczema, allergic rhinits, atopic dermatitis)
- more
What is the epidemiology of asthma?
Variable in different countries
- 5.4 million people in the UK
- more common in men <18
- more common on female >18
What is the role of eosiniphiles in asthma?
Are activated by overexpressed Th2 cells,
cause B-cell activation and IgG production,
leading to bronchial submucosal edema and smooth muscle contraction → bronchioles collapse
Leading to Bronchial Inflammation
What is the pathophysiology of allergic astmah?
IgE-mediated type 1 hypersensitivity to a specific allergen; characterized by mast cell degranulation and release of histamine after a prior phase of sensitization
What is the Pathophysiology of non-allergic Asthma?
- Irritant asthma: irritant enters lung → ↑ release of neutrophils → submucosal edema → airway obstruction
- Aspirin-induced asthma: NSAID inhibition of COX-1 → ↓ PGE2 → ↑ leukotrienes and inflammation → submucosal edema → airway obs
What are the presenting signs and symptoms of an persistant asthma patient?
- Persistent, dry cough that worsens at night, with exercise, or on exposure to triggers/irritants (e.g., cold air, allergens, smoke)
- End-expiratory wheezes
- Dyspnea
- Chest tightness
- Chronic allergic rhinitis with nasal congestion
What are severe asthma symptoms?
- Severe dyspnea
- Pulsus paradoxus
- reduced BP during inspiration (more than 10mmHg systolic) –> weak pulse during inspiration
- Hypoxemia
- Accessory muscle use
- Increased risk of pulmonary infection (in chronic asthma)
What is an acute asthma attack?
acute, reversible episode of lower airway obstruction that may be life-threatening
What are symptoms of an acute asthma attack?
- Dyspnoe
- Fear
- Agitation
What are signs of an asthma attack on examination?
- Use of accessory muscles
- agitation
- tachypnoe
- tachycardia
- reduced SPO2
- Hypercapnia
- Wheezing
- Cyanosis
- Inability to complete short symproma
On Auscultation
- Expiratory wheezing with dry crackles and prolonged expiration
- Decreased breath sounds
- indicating consollidation or “tired” of breathing, might progress into resp arrest
Percussion
- Hyerresonant chest
Which investigations would you order if you suspect someone to have asthma?
Diagnostic tests
- Spirometry
- normally reduced FEV1 with reduced FEV1/ FEV ratio
- Methacholine provocation test
- to test for hyperresponsiveness of airways
- Chext X-R
- done to exclude differentials in acute attack
- in severe attack hyperinflation
What are possible complications that can develop in an asthmatic patient?
- Acute asthma attack (moderate or severe exacerbation)
- airway remodeling
- due to chronic inflammation, similar to COPD
- Infections and more frequent pneumonia
What are possible complications that can develop from use of inhaled corticosteroids in asthma?
- Oral candidiasis
- dysphonia
- oesophageal condidiasis
What is the management of Asthma?
- Short acting ß2 agonist as reliever
- Offer inhaled corticosteroids
- if symptoms >3/7 as maintanance
- if uncontrolled with SABA alone
- Leukotriene receptor agonist (review in 4-8 Weeks) e..g montelukast
What is the prognosis of patients with asthma?
Depends on severity of asthma
- Might cause remodeling
- generally leading to reduced FEV1
- generally no change in life expectancy
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How would you manage an acute asthma attack?
- ICU admission
- SABA
- Muscareinc antagonist /inhaled anticholinergic
- O2
- IV/oral steroids
When are asthma symptoms normally worse?
- At night/early morning
- When eposed to triggers
- e.g. pollen/pets
- Cold/hot air
What drugs normally cause an exacerbation of astmah?
- NSAIDS
- ß-blocker (including glaucoma eye-drops)
Why do NSAIDs cause and exacerbation of Asthma?
NSAIDs are COx inhibiors, meaning more Arachidonic acid is available to be turned into Leukotrienes
Leukotrience cause exacerbation of Asthmah in asthmatic patients
What is a normal pCo2 for a sick asthmathic?
What happens if that changes?
Normally would expect to see a low pCO2 –> hyperventilation
If it rises –> concerned that if it’s normal or rising this suggests they are failing to keep up and will soon go into worse respiratory failure.
