Asthma Flashcards

1
Q

Describe the pathophysiology of the immediate phase of the allergic reaction. (3)

A
  1. Trigger enters the body is taken up by antigen presenting cells, which present it to T cells
    a. T cells produce inflammatory mediators, esp. IL-4 and IL-33
    b. T cells stimulate IgE production, causing allergy
  2. Trigger stimulates degranulation of mast cells
    a. This furthers the inflammatory allergic response
  3. Inflammation in the airway causes increased resistance
    a. This causes decreased airflow in the lungs
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2
Q

Describe the pathophysiology of the delayed phase of the allergic reaction. (1)

A
  1. Trigger enters the body and is taken up by antigen presenting cells, which present it to T cells
    a. T cells produce IL-12 and IFN
    b. This causes a delayed inflammatory response
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3
Q

How would you define asthma? (3)

HINT: There are 3 aspects.

A

CLINICAL DEFINITION:

  • Appropriate signs and symptoms
  • Episodic symptoms
  • Triggered symptoms
  • Variable/paroxysmal presentation
  • Response to asthma therapies

PHYSICAL DEFINITION:

  • Reversible airflow obstruction
  • Airway hyper-responsiveness

PATHOLOGICAL DEFINITION:

  • Airway inflammation
  • Airway hyper-responsiveness
  • Airway smooth muscle hypertrophy
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4
Q

List 5 symptoms of asthma.

A
Wheeze
Cough
Yellow/clear sputum
Breathlessness
Exercise intolerance
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5
Q

How do you test airway hyper-responsiveness? (2)

A

Give a small dose of histamine/methacoline/mannitol

Measure when the airways start to narrow - in asthma, this will happen sooner than in normal lungs

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6
Q

Which inflammatory cells are involved in airway inflammation in asthma? (4)

A

Neutrophils
Macrophages
Eosinophils
Lymphocytes

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7
Q

What are the different inflammatory phenotypes of asthma? (4)

A

Eosinophilic (3+% eosinophils)
Neutrophilic (61+% neutrophils)
Paucigranulocytic
Mixed

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8
Q

Which investigations would you do to diagnose asthma? (4)

A

Peak flow (serial tests)
Bronchial hyper-responsiveness test
Reversibility tests
Allergy tests

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9
Q

How do you do reversibility tests for asthma? (3)

A

Measure spirometry tests

Give a bronchodilator (usually salbutamol)

Re-measure spirometry tests

Significant difference:

  • More than 15% difference
  • More than 400ml difference
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10
Q

How would you treat chronic asthma? (2)

A
  1. Lifestyle changes, e.g.
    a. Smoking cessation
    b. Avoid triggers
    c. Check inhaler technique
    d. Written action plan
  2. Asthma drugs
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11
Q

Describe the 5 steps of the treatment ladder for asthma.

A

STEP 1:
SABA as required

STEP 2:
Add inhaled steroid, e.g. beclamethasone

STEP 3:
Add LABA, e.g. salmeterol
If ineffective, trial:
-Leukotriene receptor antagonist
-Oral theophylline

STEP 4:
Trial increased steroid dose
Trial modified-release oral theophylline

STEP 5:
Add regular oral prednisolone
Refer to asthma clinic

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12
Q

Describe the mechanism of action of theophylline. (2)

A
  1. Inhibits phosphodiesterase
  2. This increases CAMP levels, therefore decreasing bronchoconstriction
    a. This causes bronchodilation
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13
Q

Theophylline has a narrow therapeutic range.

What can theophylline toxicity cause? (3)

A

Arrhythmias
GI upset
Fits

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14
Q

What other drug may be used in prophylaxis of mild or exercise-induced asthma? (1)

A

Cromoglicate

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15
Q

Give 2 examples of leukotriene receptor antagonists.

A

Montelukast

Zafirlukast

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16
Q

What other drug might an asthma specialist give in persistent asthma?

A

Omalizumab (anti-IgE monoclonal antibody)

17
Q

Describe the mechanism of action of leukotriene receptor antagonists. (2)

A
  1. Inhibit CystLT1 receptor in the airways
    a. This reduces bronchoconstriction
  2. Also reduces inflammation
18
Q

How would you treat a non-severe, acute asthma attack? (3)

A
Nebulised salbutamol (5mg)
Oxygen
Oral prednisolone (30mg)
19
Q

What are the features of a severe acute asthma attack? (4)

A

Inability to complete sentences
HR: 110+
Resp. rate: 25+
Peak flow: 33-50% predicted

20
Q

What are the features of a life-threatening asthma attack? (5)

A
Silent chest
Confusion
Exhaustion
Cyanosis
ABG results: pO2 <8.0; pCO2 4.6-6.0; O2 sats <92%
21
Q

How would you treat a severe, acute asthma attack? (6)

A

Assess severity of attack
Warn ICU; patient will need admission

Administer:

  1. Nebulised salbutamol (5mg)
  2. Oxygen (if sats are <92%)
  3. IV hydrocortisone (100mg)
  4. Oral prednisolone (40-50mg)
22
Q

How would you treat a life-threatening asthma attack?

A
  1. Nebulised salbutamol (5mg), repeat every 15 minutes
  2. Nebulised ipratropium (0.5mg)
  3. IV magnesium sulphate (1.2-2g over 20 minutes)
  4. Monitor ECG for arrhythmias
23
Q

What investigations would you do in A&E for someone presenting with an acute asthma attack? (5)

A
PEF (if patient is fit enough)
Sputum culture
Blood tests: FBC, U&amp;Es, CRP, blood cultures
Arterial blood gases
CXR
24
Q

Describe the signs O/E of uncontrolled chronic asthma. (6)

A
Tachypnoea
Audible wheeze
Hyperinflation
Hyper-resonant percussion
Decreased air entry
Widespread, polyphonic wheeze