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JC WCS > Respiratory JC017: Cough And Wheezing: Asthma, Allergic Lung Diseases > Flashcards

Respiratory JC017: Cough And Wheezing: Asthma, Allergic Lung Diseases Flashcards

1
Q

Conditions with cough and wheezing

A

Asthma: a disease presents with **Cough + **Airflow obstruction

Diseases with cough
- Rhinitis, Sinusitis, Otitis
- **Bronchitis (chronic / postviral)
- **Asthma
- **Bronchiectasis
- Cystic fibrosis
- **Pneumonia
- ***Diffuse pulmonary fibrosis

Diseases with airflow obstruction
- **COPD
- **Asthma
- ***Bronchiolitis obliterans
- Cystic fibrosis
- Laryngeal narrowing (Organic / Functional)
- Tracheal / Major bronchial obstruction

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2
Q

Asthma

A
  • Heterogeneous disease
  • ***Chronic airway inflammation

Defined by:
1. History of respiratory symptoms
- **Wheezing (airway obstruction)
- **SOB
- Chest tightness
- ***Cough

  1. Vary over ***Time + Intensity
  2. **Variable **expiratory airflow limitation
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3
Q

Classification of Asthma

A
  1. Atopic asthma
    - individuals with a tendency to atopy / predisposition to synthesise **IgE to common allergens
    —> ↑ IgE **    Z-score —> ↑ Asthma prevalence
    - usually in children / young adults with history of infantile **eczema, **allergic rhinitis
  2. Nonatopic asthma
    - no evidence of atopy
    - adults
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4
Q

Epidemiology of Asthma

A
  • ↓ prevalence in North America, Western Europe
  • ↑ prevalence in Africa, Latin America, Part of Asia
  • 8.6% in HK
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5
Q

***Asthma risk factors

A

Host predisposition
1. Genetics: those involved in immunological pathways
2. ***Atopy
3. Gender (younger: male; adult: female)
4. Obesity

Environmental risk factors
- **Causes vs **Triggers

Causes:
1. ***Indoor aeroallergens
- house dust mites
- pets
- cockroaches

  1. ***Outdoor aeroallergens
    - alternaria
    - tobacco smoke
    - air pollution
  2. ***Occupational agents
    - 5-15% of adult onset asthma

Triggers (記: Trigger得exercise + cold air):
1. **Exercise
2. **Cold air (e.g. winter)

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6
Q

Obesity and Asthma

A
  • ↑ Co-morbidities, ↓ Lung function
  • Exact mechanisms unknown
    —> Effect on lung mechanics
    —> ***Pro-inflammatory state (cytokines from adipocytes)
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7
Q

Common allergens in HK

A
  1. **D. Pteronyssinus (i.e. house dust mite)
    - **    Der p1 + ***Der f1 allergens
    - feed on human dander
    - thrive on warm temperature and high humidity
    - allergen in fecal pellets
  2. Cockroach
  3. Cat dander
  4. Dog hair
  5. Penicillium
  6. Royal jelly
  7. Grass pollen
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8
Q

Air pollution and Asthma

A

***Dose-response relationship

↑ in health care utilisation
- hospital admission
- A/E visits
- unscheduled visits to doctors

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9
Q

Infection and Asthma

A

**Viral infection may trigger an **acute attack in pre-existing asthma

However:
- Exposure to some microbes in early infancy may protect against asthma development (Hygiene hypothesis)

Hygiene hypothesis:
- postulated by Strachan
- Allergic diseases are prevented by infections in early childhood, transmitted by contact with older children
—> Large family size
—> Having older siblings
—> Day care
—> Animal contact
—> Stable exposure
—> Drinking unpasteurised farm milk
—> Pet keeping

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10
Q

***Immunopathogenesis of Asthma

A

T-helper lymphocytes

Th0
—> **Extracellular pathogens (allergens)
—> **↑↑ Th2 (allergy-related)
—> activate ***B cells, Eosinophils, Mast cells
—> Histamine, Leukotrienes, Chemokines, TNF-α
—> Allergic inflammation and tissue damage
—> Asthma

If early exposed to microbes (Endotoxins, Mycobacteria, Virus):
Th0
—> ↑↑ Th1 (infection-related) (↓ Th2!!! —> possible ↓ allergy)
—> IFN-γ
—> Cell-mediated immunity
—> Killing of microbes, Complement activation, Killing of infected cells

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11
Q

***Mechanisms of airflow obstruction in asthma

A
  1. ***Airway inflammation
    - eosinophils
    - lymphocytes
  2. Mucous hypersecretion
    - ***goblet cells hyperplasia
  3. Smooth muscle constriction + hyperplasia
    - ***bronchospasm
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12
Q

Clinical features of Asthma

A

***Episodes of dyspnea + cough + wheeze

Episodes:
- transient / prolonged
- ***worse at night / early morning
- may present as persistent cough only (i.e. Cough-variant asthma)

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13
Q

***DDx of Wheeze

A

Generalised wheeze
- **COPD
- **Bronchiectasis
- ***Bronchiolitis obliterans
- Viral bronchiolitis (children)

Localised wheeze
- Tumour
- Foreign body

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14
Q

***Diagnosis of Asthma

A
  1. Compatible history
    - **symptomatology
    - **    environmental triggers
  2. Variable airflow obstruction
    - demonstrate presence of airflow obstruction
    - improve in FEV1 (    >200ml / ***>=12% from baseline) / PEF after bronchodilator
    - diurnal variation in PEF / variation in PEF over a period of time
  3. Non-specific airway hyperresponsiveness
    - bronchial challenge test (    NOT essential for Dx)
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15
Q

Assessment of Asthma

A
  1. Severity
    - assessed **retrospectively from **level of treatment required to control symptoms / exacerbations
    - assessed after patient has been on controller treatment for **several months
    - severity is **    NOT static, may change over time / as different treatments become available
  2. Identify triggering factors
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16
Q

***Categories of Asthma severity

A

記: PRN controller —> Low dose ICS —> LABA —> Moderate/High dose ICS + LABA + Add-on agents

Mild:
- well-controlled with Steps 1 / 2
- ***PRN controller / Low dose ICS

Moderate:
- well-controlled with Step 3
- ***Low dose ICS / LABA

Severe:
- require Step 4 / 5
- ***Moderate / High dose ICS/LABA +/- Add-on (e.g. LAMA)
- or remain uncontrolled despite treatment

17
Q

Treatment goals of Asthma

A

Complete control
- No attacks, A/E visits, hospitalisation
- No symptoms / fewest possible
- No limitation of activity
- **Normal / Near normal lung function
- **Least aerosol bronchodilator use
- Least SE from medication

18
Q

Management of Asthma

A
  1. Pharmacotherapy
    - ***Relievers: Bronchodilators
    —> SABA
    —> LABA
    —> Anticholinergics (SAMA, LAMA)
    —> Theophylline
  • **Preventors: Anti-inflammatory drugs
    —> **    Inhaled / Oral steroids
    —> Nedocromil sodium
    —> Sodium cromoglycate
    —> **Leukotriene receptor antagonist (LTRA) (Montelukast)
    —> **    Anti-IgE (Omalizumab)
    —> Other biologics (e.g. Anti-IL5)
  1. Prevention
  2. Patient education
19
Q

***Bronchodilators

A
  1. Short-acting β2 agonists (SABA)
    - Salbutamol (Ventolin)
    - Terbutaline (Bricanyl)
  2. Long-acting β2 agonists (LABA)
    - Salmeterol (Serevent)
    - Formoterol (Oxis)
  3. Anticholinergic (Tiotropium (LAMA), Ipratropium (SABA))
  4. Xanthines (Theophylline)
20
Q
  1. Short-acting β2 agonists (SABA)
A
  • Use when necessary (PRN)
  • Inhaled vs Oral
  1. Salbutamol (Ventolin)
  2. Terbutaline (Bricanyl)

SE:
- tremor, headache, tachycardia, arrhythmia (∵ ***sympathomimetic action)
- ↑ mortality with frequent use alone

21
Q
  1. Long-acting β2 agonists (LABA)
A
  • ***Regular use
  • Prolonged bronchodilation: ***12 hours
  1. Salmeterol (Serevent)
  2. Formoterol (Oxis)
    —> In combination with ***Low dose ICS (<800 ug/day) as an alternative to High dose ICS
22
Q

***Anti-inflammatory preventors

A
  1. ***Inhaled / Oral steroids
    - Beclomethasone (Becotide, Becloforte)
    - Budesonide (Pulmicort)
    - Fluticasone (Flixotide)
  2. Nedocromil sodium
  3. Sodium cromoglycate (used in paediatrics)
  4. ***Leukotriene receptor antagonist (LTRA) (Montelukast)
  5. ***Anti-IgE (Omalizumab)
  6. Other biologics (e.g. Anti-IL5)
23
Q
  1. Inhaled / Oral / IV steroids
A

Oral / IV steroids:
- used in Acute episodes (avoid long term use ∵ SE)

Inhaled steroids:
1. Beclomethasone (Becotide, Becloforte)
2. Budesonide (Pulmicort)
3. Fluticasone (Flixotide)

Benefits:
- Improve symptom control
- **↓ exacerbation
- **↓ mortality
- ***↓ lung function decline

Disadvantage:
- NOT an immediate bronchodilator
- take ***~1 week to work

(SE (UpToDate):
- Hoarseness
- Oral thrush
- Allergic contact dermatitis
- Systemic SE of steroids)

24
Q
  1. Leukotriene receptor antagonist
A

Montelukast
- **Oral
- OD
- Mild to Moderate asthma
- Effective in **exercise-induced bronchospasm
- Effective in preventing aspirin-induced asthma, angioedema etc.
- **Steroid-sparing effect
- **Unmask previously undiagnosed ***Churg-Strauss syndrome (disorder marked by blood vessel inflammation) (∵ steroids mask Churg-Strauss syndrome)

25
Q
  1. Anti-IgE Ab
A

Omalizumab

  • Indicated in **Moderate - Severe asthma with suboptimal control despite **maximal ICS/LABA +/- LTRA / theophylline / steroid-dependent asthma
  • ONLY for ***atopic asthma (i.e. elevated IgE + positive skin prick test)

SE:
- ***Anaphylaxis

26
Q

***Guidelines for Asthma treatment

A

***GINA (Global Initiative for Asthma)

Controller:
Step 1: PRN Low dose ICS-Formoterol
Step 2: Daily Low dose ICS / PRN Low dose ICS-formoterol
Step 3: **Low dose ICS-LABA
Step 4: **Medium dose ICS-LABA
Step 5: ***High dose ICS-LABA (+/- add-on therapy e.g. Tiotropium, Anti-IgE, Anti-IL5/5R, Anti-IL4R)

Reliever:
- PRN Low dose ICS-Formoterol (ICS-LABA) / PRN SABA

27
Q

GINA assessment of asthma control

A

Questionnaire
1. Symptom control
- **Daytime / Nighttime symptoms
- **Frequency of use of reliever
- ***Activity limitation

  1. Risk factors for poor asthma outcomes
28
Q

Prevention of Asthma

A
  1. House dust mite avoidance (e.g. Atopic asthma)
    - encasement of mattresses, pillows, duvets with vinyl covers
    - hot water wash of all bedding regularly < 2 weeks
    - remove carpets
    - no stuffed toys
    - cleaning of environments
  2. Cat allergens
    - remove cat
    - hard surface floor
    - remove upholstered furniture
    - HEPA filter
    - wash cat weekly
29
Q

Patient education

A
  1. What is asthma
  2. What are triggers and how to avoid
  3. How drugs work
  4. How to use inhaler properly
  5. Necessary to use preventors regularly
  6. What to do during acute attack
  7. When to contact doctor / go to A/E
30
Q

Monitoring of PEF (SpC FM)

A

Short-term monitoring:
- Following an exacerbation, to monitor recovery
- Following a change in treatment, to help in assessing whether the patient has responded
- If symptoms appear excessive (for objective evidence of degree of lung function impairment)
- To assist in identification of occupational or domestic triggers for worsening asthma control

Long-term monitoring:
- For earlier detection of exacerbations, mainly in patients with poor perception of airflow limitation
- For patients with a history of sudden severe exacerbations
- For patients who have difficult-to-control or severe asthma

JC WCS (134 decks)

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