Lecture 15 - Asthma

Question 1

Asthma

Answer 1

Chronic inflammatory airway disease with intermittent airway obstruction and hyper -reactivity

Disease of the small airways (bronchioles) with PEF reduction

Question 2

Pathophysiology

Answer 2

Type 1 hypersensitivity reaction (IgE)

1. Allergen e.g. pollen picked up by dendritic cells and presented to Th2 cells
2. Type 2 helper cells (Th2) produce cytokines:
   - interluekin 4 and 5
3. IL -4 secrete Ig E antibodies which stimulate mast cells to secrete granules containing histamines and prostoglandins
4. IL 5 cause eosinophils to release cytokines and leukotrienes - damage endothelium
5. Smooth muscle spasm and mucus hyperproduction narrow airways

Question 3

Effects of asthma

Answer 3

Smooth muscle hypertrophy

Mucus hyperproduction

Thickened basement membrane

Less ciliar so decreased clearance of mucus

Reduced airway diameter

Question 4

Symptoms of asthma

Answer 4

Chest tightness
Coughing
Dyspnea
Wheezing when exhaling

May see atopy

Question 5

Epithelial cell type in trachea

Answer 5

Psuedostratified columnar

Question 6

Atopy

Answer 6

Group of conditions that are triggered by allergens e.g.

• eczema
• hayfever
• asthma

Question 7

Triggers of athma

Answer 7

Pollen
Pets
Dust 
Cigarette smoke
Cold weather
Exercise
Infection
Aerosols

Question 8

Diagnosis of athma

Answer 8

PEF spirometer - below avergae and worse in the morning and night

Spirometry - obstructive pattern but better with bronchodilator

• reduced FEV1
• FEV1/FVC below 70%

Question 9

Differentiation between asthma and COPD

Answer 9

Dry cough
History of atopy
Typically in children and young people
Reversible with bronchodilator

Question 10

Management of asthma

Answer 10

• avoid triggers
• salbutamol inhaler
• corticosteroid - preventor

Question 11

Salbutamol

Answer 11

Beta 2 agonist -

1. Adenyl cyclase converts ATP to cyclic AMP
2. Cyclic AMP activate protien kinase A
3. Causes bronchodilation

Question 12

Identification of severe asthma

Answer 12

• Difficulty completing sentences
• Respiration above 25 bpm
• Saturation above 925%
• Wheeze
• Increased HR above 115
• PEF below predicted

Question 13

Identification of life threatening asthma

Answer 13

• Respiration below 25 breaths per minute
• Saturation below 92%
• No breath sounds
• Decompensation so decreased blood pressure
• Cyanosis
• PEF less than 1/3rd of predicted