Respiratory - Asthma

Question 1

What is asthma?

Answer 1

Chronic inflammatory airway disease leading to variable airway obstruction

Due to hypersensitivity causing constriction and airflow obstruction

Question 2

What other atopic conditions are there?

Answer 2

Eczema
Hay fever
Food allergies

Patients with one of these conditions more likely to have others

Question 3

When does asthma typically present?

Answer 3

Childhood

Can present at any age
Adult-onset asthma
Occupational asthma

Question 4

How does asthma present?

Answer 4

Shortness of breath
Chest tightness
Dry cough
Wheeze

Widespread polyphonic expiratory wheeze

Question 5

What are some triggers of asthma?

Answer 5

Infection
Night-time or early morning
Exercise
Animals
Cold, damp or rusty air
Strong emotions

Question 6

What drugs can exacerbate asthma?

Answer 6

Beta blockers (particularly non-selective e.g. propranolol)
NSAIDS

Question 7

What investigations are used for asthma?

Answer 7

Spirometry
Reversibility testing
Increase greater than 12% indicates asthma
Fractional exhaled nitric oxide (FeNO)
NO is a marker of airway inflammation, over 40ppb is positive
Peak flow variability
Direct bronchial challenge testing
Inhaled histamine or methacholine to stimulate bronchoconstriction
20% reduction is positive

Question 8

How do beta agonists work for asthma?

Answer 8

Adrenaline acts on beta-2 receptors to cause relaxation

Short-acting beta-2 agonists (SABA) e.g. Salbutamol

Long-acting beta-2 agonists (LABA) e.g.
Salmeterol

Question 9

How do inhaled corticosteroids work?

Answer 9

Reduce inflammation and reactivity of airways

Used to maintain or prevent

Beclomethasone

Question 10

How do long-acting muscarinic antagonists work?

Answer 10

LAMA

Blocks ACh receptors

ACh receptors stimulated by parasympathetic nervous system and cause contraction of bronchial smooth muscles

Blocking ACh receptors dilates bronchioles and reverses bronchoconstriction

Question 11

How do leukotriene receptor antagonists work?

Answer 11

Montelukast

Block effects of leukotrienes which are produced by immune system and cause inflammation, bronchoconstriction and mucus secretion

Question 12

Why do you need to monitor plasma theophylline levels?

Answer 12

Narrow therapeutic window and can be toxic

Question 13

What is maintenance and reliever therapy?

Answer 13

Combination inhaler
Inhaled corticosteroid and a fast and long acting beta-agonist e.g. formoterol

Replaces all other inhalers

Used as both preventer and reliever

Question 14

What is the stepwise approach for managing asthma?

Answer 14

1. SABA e.g. salbutamol as required
2. ICS low dose
3. Leukotriene receptor antagonist e.g. montelukast
4. LABA e.g. salmeterol
5. Maintenance and reliever therapy
6. Increased ICS dose
7. High dose ICS or adding LAMA or theophylline
8. Specialist management

Question 15

What is the additional management of asthma?

Answer 15

Yearly flu jab
Regular exercise
Avoid smoking
Avoid triggers

Question 16

What is an acute exacerbation of asthma?

Answer 16

Rapid deterioration in symptoms

Question 17

What are the presenting features of an acute exacerbation of asthma?

Answer 17

Progressively short of breath
Accessory muscle use
Tachypnoea
Symmetrical expiratory wheeze
Tight chest on auscultation

Question 18

What does an acute exacerbation of asthma look like on an ABG?

Answer 18

Respiratory alkalosis

Tachypnoea causes a drop in CO2

Normal pCO2 or low PO2 indicates they are getting tired, indicates life-threatening asthma

Respiratory acidosis due to pCO2 is extremely bad

Question 19

How is acute asthma graded?

Answer 19

Question 20

How are acute asthma exacerbations managed?

Answer 20

Need to escalate early to seniors and ICU

Question 21

Why is intubation of life-threatening asthma made early?

Answer 21

Very difficult to intubate with severe bronchoconstriction

Question 22

Why does serum potassium need to be monitored with salbutamol use?

Answer 22

Potassium absorbed from blood into cells causing hypokalaemia

May also cause tachycardia and lactic acidosis

Question 23

How are patients managed after an acute attack?

Answer 23

Optimise long-term management
Asthma self-management plan
Rescue pack of oral steroids