S8) Asthma Flashcards

1
Q

What is asthma?

A

Asthma is a chronic inflammatory disorder of the airways, wherein widespread but variable airflow obstruction and increased airway responsiveness to a variety of stimuli occurs

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2
Q

Identify 5 defining characteristics of asthma

A
  • Chronic inflammatory process
  • Susceptibility
  • Variable airflow obstruction
  • Airway hyper-responsiveness
  • Reversibility
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3
Q

Airways obstruction is a feature of both Asthma and Chronic Obstructive Pulmonary Disease (COPD).

How can one distinguish between the two conditions?

A
  • Asthma: airway obstruction is often reversible (> 15% improve spontaneously, with bronchodilators/steroids)
  • COPD: airway obstruction is not fully reversible (< 15% improve with treatment)
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4
Q

Identify the most influential cells in asthma

A

Asthma is a chronic inflammatory process driven by TH2 cells

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5
Q

What do TH2 cells do?

A
  • Release cytokines, which attract and activate inflammatory cells (incl. mast cells and eosinophils)
  • Activate B cells, which produce IgE
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6
Q

In a sensitised atopic asthmatic, exposure to antigen results in a 2 phase response.

Briefly, identify and describe these 2 phases

A
  • Immediate response (< 20 mins)
  • Late phase response (3 – 12 hours later)
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7
Q

What type of immune response is the immediate response to asthma?

A

The immediate response is an example of type 1 hypersensitivity

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8
Q

In 5 steps, describe the immediate response to asthma

A

⇒ Allergen interacts with specific IgE antibodies

⇒ Mast cell degranulation occurs

Mediators are released (histamine, prostaglandin D2, leukotriene)

⇒ Bronchial smooth muscle contracts

Bronchoconstriction occurs

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9
Q

What type of immune response is the late phase response to asthma?

A

The late phase response is an example of type IV hypersensitivity

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10
Q

The late phase response to asthma involves inflammatory cells.

What do they do?

A

Inflammatory cells release mediators and cytokines which cause airway inflammation

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11
Q

Identify 4 inflammatory cells involved in the late phase response to asthma

A
  • Eosinophils
  • Mast cells
  • Lymphocytes
  • Neutrophils
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12
Q

What do eosinophils do in the late phase response to asthma?

A

Eosinophils release Leukotriene C4 and other mediators, some of which are toxic to epithelial cells, and causes shedding of epithelial cells

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13
Q

Identify 5 events which causes the airway narrowing observed in asthma as a result of inflammation

A
  • Mucosal oedema due to vascular leak
  • Bronchial wall thickening due to inflammatory cell infiltration
  • Mucous over-production
  • Smooth muscle contraction
  • Epithelium shedding
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14
Q

Identify 6 major precipitating factors for asthma

A
  • Allergens e.g. pollen, animals hair/dander
  • Cold air (airway hyper-responsiveness)
  • Exercise
  • Irritants e.g. car exhaust fumes, smoke, strong smells
  • Emotional distress
  • Viral infections
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15
Q

Identify 6 signs and symptoms of asthma

A
  • Expiratory wheeze
  • Cough
  • Diurnal variability (worse at night & morning)
  • Breathlessness
  • Chest tightness
  • Exercise induced wheeze
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16
Q

What 3 questions can one ask a patient to ascertain asthma?

A
  • Have you had difficulty sleeping because of your asthma symptoms?
  • Have you had your usual asthma symptoms during the day?
  • Has your asthma interfered with usual activities?
17
Q

What is the most common test used to confirm a diagnosis of asthma?

A

Spirometry

18
Q

What do the spirometry tracings in an asthmatic patient usually show?

A

Obstructive condition – FEV1/FVC is reduced

19
Q

Which further test can be used to confirm an asthma diagnosis if the spirometry tracing is normal?

A

Methacholine / histamine challenge to determine airway hyper-responsiveness

20
Q

Identify 3 investigations used to measure the airway inflammation in asthma

A
  • Peripheral blood eosinophil count (FBC)
  • Induced sputum (eosinophils, neutrophils)
  • FeNO (exhaled nitric oxide)
21
Q

Identify 5 aims of asthma management

A
  • No daytime symptoms
  • No night-time awakening due to asthma
  • No asthma attacks
  • No limitations on activity
  • Normal lung function
22
Q

Identify and describe 3 factors which affect asthma treatment

A
  • Pharmacological management: incorrect or suboptimal prescribing
  • Clinical factors: environmental (triggers), medication, co-existing condition
  • Behavioural factors: sub-optimal adherence, poor inhaler technique, smoking
23
Q

Outline the principles of asthma treatment

A
  • Smoking cessation
  • Inhaler technique
  • Monitoring
  • Pharmacotherapy
  • Lifestyle
  • Education
24
Q

Identify the 5 stages in asthma treatment

A
  1. Regular preventer
  2. Initial add-on therapy
  3. Additional add-on therapies
  4. High dose therapies
  5. Continuous/frequent use of oral steroids
25
What is the regular preventer in asthma treatment? (first line)
Low dose inhaled corticosteroid (ICS)
26
What is the initial add on therapy in asthma treatment? (second line)
- Low dose inhaled corticosteroid (ICS) - Inhaled long acting β2 agonists (LABA)
27
What are the additional add on therapies in asthma treatment? (third line)
**If no response / inadequate control from LABA:** - Increase ICS dose + continue LABA - Continue LABA + ICS and trial LTRA, LAMA or theophylline
28
What are the high dose therapies in asthma treatment? (fourth line)
- Increase to high-dose ICS - Addition of 4th drug (LTRA, theophylline, LAMA, β2-agonist tablet)
29
Describe the continuous/frequent use of oral steroids in asthma treatment (last line)
- Low dose steroid tablet - Maintain high dose ICS - Refer to specialist care
30
Describe the treatment of acute severe asthma
- Oxygen (high flow, 94-98%) - Nebulised salbutamol - Oral prednisolone
31
Describe the treatment of life threatening asthma
- Nebulised ipratropium bromide (add to acute treatments) - IV magnesium and/or IV aminophylline (add to acute treatments) - Discuss with senior doctor and ICU