Respiratory: Asthma - Diagnosis Flashcards

1
Q

Define asthma [1]

A

A chronic inflammatory airway disease that causes a combination of cough, wheeze or breathlessness with
variable airflow obstruction

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2
Q

What are the 5 phenotypes of asthma? [5]

A

◦ Allergic asthma
◦ Non-allergic asthma
◦ Adult-onset (late-onset) asthma
◦ Asthma with persistent airflow limitation
◦ Asthma with obesity

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3
Q

Describe the difference in cells found in the phlegm of allergic and non-allergic asthma [2]

A

◦ Allergic asthma: eosinophilic
◦ Non-allergic asthma: neutrophilic

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4
Q

Which type of asthma is hard to treat with corticosteroids / difficult to treat patients?

◦ Allergic asthma
◦ Non-allergic asthma
◦ Adult-onset (late-onset) asthma
◦ Asthma with persistent airflow limitation
◦ Asthma with obesity

A

◦ Allergic asthma
◦ Non-allergic asthma
◦ Adult-onset (late-onset) asthma
◦ Asthma with persistent airflow limitation
◦ Asthma with obesity

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5
Q

Which of the following is most likely to be due to occupational environment?

◦ Allergic asthma
◦ Non-allergic asthma
◦ Adult-onset (late-onset) asthma
◦ Asthma with persistent airflow limitation
◦ Asthma with obesity

A

Which of the following is most likely to be due to occupational environment?

◦ Allergic asthma
◦ Non-allergic asthma
◦ Adult-onset (late-onset) asthma
◦ Asthma with persistent airflow limitation
◦ Asthma with obesity

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6
Q

Explain which part of the lung is most commonly affected in asthma? [1]

A

Terminal bronchioles: surrounded by smooth muscle

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7
Q

Which type of hypersensitivty is asthma? [1]

A

Type 1

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8
Q

Describe the pathway that causes asthma [5]

A

i. Allergen picked up by dendritic cells and presented by MHC Class II molecules
ii. CD4 cells activate the TH-2 lymphocytes through the release of IL4, IL5, IL13.
iII. IL 4 leads to the production of IgE antibodies: coat mast cells and stimulate degranulation and the release histamines, leukotrienes and prostaglandins
iv. IL-5 activates eosinophils: causes more cytokine & leukotrienes release
v IL-9 = mast cell proliferation

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9
Q

Describe the pathophysiology of asthma

A

Airway inflammation:
- Immune cells activated by TH2, mast cells and eosinophils
- Causes pro-inflam mediators (cytokines, chemokines, histamines, leukotrines) to cause airway oedema, mucus production, and bronchoconstriction

Bronchoconstriction
- narrowing of the airways and obstruction of airflow.

Airway hyperresponsiveness
- airways exhibit excessive narrowing in response to various stimuli, such as allergens, irritants, and cold air
- mediated by several factors, including the release of inflammatory mediators, increased airway smooth muscle contractility, and impaired bronchodilator mechanisms

Mucus production and airway remodeling:
* Chronic inflammation causes airway remodeling
* Subepithelial fibrosis, increased smooth muscle mass, mucus gland hypertrophy, and angiogenesis.

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10
Q

A number of patients with asthma are sensitive to which drug? [1]

Patients who are most sensitive to asthma often suffer from []? [1]

A

A number of patients with asthma are sensitive to aspirin.

Patients who are most sensitive to asthma often suffer from nasal polyps. Remember the nose is part of the respiratory tract from a histological point of view.

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11
Q

What are the classical features of asthma? [4]

What helps to create a clinical picture regarding features and treatment? [1]

A

episodic symptoms; typically worse at night:
* widespread, polyphonic expiratory wheeze (occurs from turbulent airflow in narrow airways)
* breathlessness
* chest tightness: airway obstruction and increasde work of breathing
* cough: dry or productive; worse at night or early in morning.

Symptoms should improve with bronchodilators. No response to bronchodilators reduces the likelihood of asthma.

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12
Q

TOM TIP: A localised monophonic wheeze is not asthma.

Give the top differentials of a localised wheeze [3]

A

Inhaled foreign body
tumour
a thick sticky mucus plug obstructing an airway (pneumonia)
pulmonary oedema

A chest x-ray is the next step.

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13
Q

Which drugs can worsen asthma? [3]

A

Non-selective beta blockers: propranolol
- blocking the beta receptors in the lungs, which leads to bronchoconstriction and breathing difficulties.

Non-steroidal anti-inflammatory drugs: aspirin, ibuprofen or naproxen
- This reaction is known as aspirin-exacerbated respiratory disease (AERD) or aspirin-induced asthma.

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14
Q

Which cells are responsible for the acute phase of asthma? [1]

Which cells are responsible for the late phase of asthma? [3]

A

Early: mast cells

Late: Th2 helper cells –> B cells –> IgE & Eiosinophils

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15
Q

What’s the difference between asthmas that are considered extrinsic, intrinsic and occupational? [1]

A

Extrinsic asthma is caused by:
- Air pollution
- Allergens
- Maternal smoking
- Genetics
- More responsive to steroid tx

Intrinsic asthma is:
- non-allergic
- Less responsive to steroids
- Colds / infections can trigger

Occupational
- Allergens at work

Don’t learn too muc detial

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16
Q

Describe the diagnostic pathway for asthma

A

There is no signal diagnostic test

17
Q

Describe the features that would make you suspicious that a patient has asthma [6]

A

More than one of the following in episodes:
 wheeze
 breathlessness
 chest tightness
 cough

diurnal variability

Triggered by allergen, exercise, cold air, aspirin or β-blocker

Atopic features
 Eczema
 Hayfever

Fx

Low PEFR or FEV (note: both decrease with age)

18
Q

Describe the features that would make you less suspicious that a patient has asthma [6]

A

Dizziness, light-headedness or peripheral tingling

Productive cough in the absence of wheeze or breathlessness

Repeatedly normal examination when breathless

V oice disturbance

Symptoms only with colds

Significant smoking history (>20 pack years)

Cardiac disease

Normal PEF or FEV1when symptomatic

19
Q

Describe the diagnostic pathway for diagnosis of asthma

A
  1. Clinical suspicion based off clinical assessment (history, exam, previous medical records)
  2. IF high probabilty of asthma:
     Code as suspected asthma and start treatment
    Assess response to treatment:
    Good response = asthma;
    poor response then intermediate probability of asthma.
  3. Next: Test for airway obstruction using spirometry and bronchodilator reversibility:
  • Test for variability by investigating:
     Reversibility
     PEF charting
     Challenge tests
  • Test for eosinophilic inflammation:
     FeNO
     Blood eosinophs
     Skin prick test, IgEIf good response: asthma
    If poor response: investigate other more likely diagnosis

BTS pathway

20
Q

What does FeNO test? [1]

What level of FeNO would be considered positive for asthma in adults? [1]
What level of FeNO would warrent further consideration for asthma positive for asthma in adults? [1]
What level of FeNO would you consider a different diagnosis than asthma in adults? [1]

A

fractional exhaled nitric oxide (FeNO):

FeNO tests the amount of NO produced by iNOS, which is raised in eisinophils (which are raised in asthma)

  • in adults a level of >= 40 parts per billion (ppb) is considered positive
  • 25-39 ppb would warrant further investigations
  • < 25 ppb would be a different diagnosis
21
Q

What level of FeNO would be considered positive for asthma in children? [1]

A
  • in children a level of >= 35 parts per billion (ppb) is considered positive
22
Q

What spirometry result would be considered obstuctive for asthma? [1]

A

FEV1/FVC ratio less than 70% (or below the lower limit of normal if this value is available) is considered obstructive (e.g., asthma or COPD).

23
Q

What would indicate positive reversibility testing in adults [2] and children [1]?

A

Reversibility testing:
- in adults, a positive test is indicated by an improvement in FEV1 of 12% or more and increase in volume of 200 ml or more
- in children, a positive test is indicated by an improvement in FEV1 of 12% or more

24
Q

Describe what is meant by direct bronchial challenge testing [1]

What results would indicate a positive result for asthma? [1]

A

Direct bronchial challenge testing is the opposite of reversibility testing.

Inhaled histamine or methacholine is used to stimulate bronchoconstriction, reducing the FEV1 in patients with asthma.

NICE say a PC20 (provocation concentration of methacholine causing a 20% reduction in FEV1) of 8 mg/ml or less is a positive test result.

25
Q

How long would you ask a patient to keep a peak flow diary for when investigating asthma? [1]

What results would indicate a positive result for asthma? [1]

A

Peak flow variability is measured by keeping a peak flow diary with readings at least twice daily over 2 to 4 weeks.

NICE says a peak flow variability of more than 20% is a positive test result, supporting a diagnosis.

PEF: 20%
FEV1: 12% or 200ml

26
Q

How do you distinguish between COPD and asthma? [5]

What is the difference regarding steroid strength? [2]

A

Asthma:
- Daily FEV1 variation
- Reversibility
- Asthma is inflammatory - so use higher dose steroids

COPD:
- Older
- Smoking history
- Productive sputum
- Chronic damage to airway: lower dose steroids

27
Q

Draw an obstrucive spirometry result [1]

A
28
Q

What do you need to consider about spirometry when investigating asthmatics? [1]

A
  • many asthmatics may have normal spirometry especially when not symptomatic
29
Q

Label A-E [5]

A

A: FEV1/FVC< 70%
B: >12% or 200ml improvement in FEV1
C: >40 ppb
D: concentration required to cause 20% fall in FEV1 (PC20) OF 8mg/ml or less
E: 20% variability

30
Q

The NICE guidelines (2020) recommend which two initial investigations in patients with suspected asthma? [2]

Where there is diagnostic uncertainty after initial investigations, the next step is []

Where there is still uncertainty, the next step is []

A

Initial test:
* Fractional exhaled nitric oxide (FeNO)
* Spirometry with bronchodilator reversibility

Diagnostic uncertainty:
- testing the peak flow variability.

Continued uncertainty:
- a direct bronchial challenge test with histamine or methacholine.

31
Q

What do you give patients when performing bronchial provocation testing? [1]

Describe how you pefrom bronchial provocation testing [2]

A

Bronchial provocation testing is performed with methacholine or histamine

Increasing doses are given until the patient’s forced expiratory volume (FEV1) drops by 20% in one second. This dose is termed the PC20.

A PC20 dose of 8 mg/ml or less reflects a positive result.