4.2 Asthma and Cystic Fibrosis

Question 1

What is the difference between dyspnoea, cough, sneeze, wheeze, stridor, and crackling sounds?

Answer 1

Dyspnoea = respiratory distress

Cough = expulsion of irritants (closed glottis)

Sneeze = expulsion of irritants (open glottis)

Wheeze = narrowed airways

Stridor = intense wheeze

Crackling = sudden opening of airways, fluids

Question 2

What are the signs + symptoms of asthma?

Answer 2

Wheeze
Shortness of breath
Cough
Chest tightness

Question 3

What are the predisposing factors for asthma?

Answer 3

Past allergies
Family history
Maternal smoking
Male
Indoor allergen exposure
Genetics

Question 4

What are the triggers for asthma?

Answer 4

Viral respiratiory infection
Exercise
Exposure to specific allergens
Environmental irritants
Dietary triggers
Medicine
Occupational exposures

Question 5

What are the triggers for asthma?

Answer 5

Viral respiratiory infection
Exercise
Exposure to specific allergens
Environmental irritants
Dietary triggers
Medicine
Occupational exposuresd

Question 6

What is the pathophysiology of asthma?

Answer 6

Muscles surrounding the bronchial tubes tighten (bronchospasm)

Narrows air passage and interrupting the normal flow of air into and out of the lungs

Increase mucous secretion forms mucous plug + swelling of bronchial tubes

Question 7

Asthma is a type 1 hypersensitivity. What does this mean?

Answer 7

Immune reaction to non-harmful substance

Mediated by T-cell (TH2), B-cells (produced by IgE), mast cells, and eosinophils

Question 8

What is the difference between sensitisation and re-exposure?

Answer 8

Sensitisation = first exposure, priming of mast cells

Re-exposure = inflammatory response driven my sensitised/primed mast cells

Question 9

What are the steps leading to an acute allergic reaction?

Answer 9

1. At first exposure to allergen, antigen presenting cell (APC) rpocess antigen + present to TH2 cell
2. TH2 cells release IL-4, IL-5, and IL-13 which activate B-cells
3. B-cells proliferate + differentiate into plasma cells that synthesise IgE antibody
4. IgE binds to mast cells via Fc region = sensitising mast cells
5. Subsequent exposures = mast cells with IgE bind to antigen + release inflammatory molecules eg histamine, cytokines, chemokines
6. Allergy symptoms

Question 10

Medications for asthma can be relievers or preventers. What are these and what are their possible side effects?

Answer 10

Relivers = short-acting beta-2 agonist (salbutamol)

Preventers = Inhaled corticosteroids (glucocorticosteroids)

Side effects = reduced slaiva flow, thrush, caries, dental eroision, bad taste, periodontitis

Question 11

Anxiety can be a trigger for asthma. What clinical considerations are important to keep in mind for asthmatic patients?

Answer 11

Availability of emergency drugs

Sedation = avoid narcotics + barbiturates (histamine releasing)

Medication selection = aspirin + NSAIDs bad, paracetamol good

OH strategy = fluroide prevents caries

Question 12

What is cycstic fibrosis?

Answer 12

Chronic disease
Genetic abnormality
Affects respiratory + gastrointestinal tracts

Question 13

What are the causes of cystic fibrosis?

Answer 13

Mutation or variatin in gene cystic fibrosis transmembrane

Autosomal recessive (two copies of gene must be present)

Question 14

What is the pathophysiology of cystic fibrosis?

Answer 14

Affects chloride channels on epithelial cells

Airway = decreased chloride excretion, decreased water, dehydrated mucus, decreased mucociliary action, increased respiratory bacterial infections

Sweat + salivary glands = reduced chloride reabsorption, increase salt concentration