Asthma

Question 1

What is asthma characterised by?

Answer 1

Reversible decreases in the FEV1:FVC (less than 70-80% suggests increased airway resistance)
Variations in PEF which improve with a B2 agonist

Question 2

What is the parasympathetic control of bronchial calibre?

Answer 2

Acetylcholine acts on muscarinic- M3 receptors
Bronchoconstriction
Increase mucus

Question 3

What is the sympathetic control of bronchial calibre

Answer 3

Circulating adrenaline acts on B2-adrenoceptors on bronchial smooth muscle to cause relaxation
Sympathetic fibres releasing noradrenaline, acting at B2-adrenoceptors on parasympathetic ganglia inhibit transmission
B2-adrenoceptors on mucus glands inhibit secretion

Question 4

What can asthma be provoked by?

Answer 4

Allergens
Cold air
Viral infections
Smoking
Exercise

Question 5

What are the clinical features of asthma?

Answer 5

Wheezing
Breathlessness
Tight chest
Cough (worse at night/exercise)
Decreases in FEV1, reversed by a B2-agonist

Question 6

What are spasmogens?

Answer 6

Histamine
Prostaglandin D2
Leukotrienes C4 + D4

Question 7

What are chemotaxins?

Answer 7

Leukotriene B4, PAF
Lead to late phase
Attract leukocytes, especially eosinophils and mononuclear cells
Leading to inflammation + airway hyper-reactivity

Question 8

What are B2-adrenoceptor agonists?

Answer 8

Salbutamol (Ventolin)
Agents of 1st choice
Increases FEV1
Act on B2-adrenoceptors on smooth muscle to increase cAMP
Given by inhalation
Prolonged use may lead to receptor down-regulation

Question 9

What are long acting beta agonists (LABA)?

Answer 9

Salmeterol
Given for long term prevention and long term control (overnight)
Do not relieve an attack
Used in addition to other agents

Question 10

What are xanthines?

Answer 10

Theophylline
Bronchodilators (not as good as B2 agonists, 2nd line)
Oral (or i.v aminophyliine in emergency)

Question 11

What must you monitor when prescribing xanthines?

Answer 11

Plasma concentration as has a narrow therapeutic index
Range of interactions and largely removed by hepatic metabolism
May cause hypokalaemia especially when used with B2 agonists
Phosphodiesterase inhibitors

Question 12

What are muscarinic M-receptor antagonists?

Answer 12

ipratropium (short acting t.d.s)
Tiotropium (long acting once daily)
Block parasympathetic bronchoconstriction
Inhalation: prevents antimuscarinic side effects
Limited/little use in asthma, widely used in COPD

Question 13

What are anti-inflammatory agents?

Answer 13

Preventative: do not reverse an attack
Corticosteroids:
Beclometasone (becotide, inhalation) or prednisolone (oral)
Anti-inflammatory by activation of intracellular receptors, leading to altered gene transcription (decrease cytokine production) and production of lipocortin

Question 14

What does lipocortin do?

Answer 14

Inhibits synthesis of leukotrienes and prostaglandins

Blocks action of phospholipase 2 forming arachidonic acid

Question 15

When are steroids given?

Answer 15

Given with B2 agonists- reduce receptor down-regulation

Question 16

What are the side effects of inhaled steroids?

Answer 16

Throat infections (immunosuppression leading to superficial fungal infections)
Hoarseness (laryngeal myopathy)- recommend rinsing mouth out after inhalation, use a spacer device

Question 17

What are the side effects of oral steroids?

Answer 17

Adrenal suppression
Diabetes
Osteoporosis
Immunosuppression

Question 18

What are cromones?

Answer 18

Sodium cromoglicate 
Preventative (both early and late)
Poorly effective
Inhalation 
Uncertain action- 
May reduce reflexes of sensory nerves
Reduce release of PAF and cytokines

Question 19

What are leukotriene receptor antagonists (LTRAs)?

Answer 19

Montelukast
Recent introduction, now have increased role as add on therapy
Preventative AND bronchodilator
Antagonise actions of leukotrienes

Question 20

What is the stepped care approach for adults with asthma?

Answer 20

Step 1: Occasional bronchodilator (short acting B2-agonist)
Step 2: Short acting B2-agonist + regular inhaled steroid
Step 3: Step 2 + trial of LABA (if this fails LTRA or xanthine)
Step 4: Increased dose of inhaled steroid
Step 5: Add oral steroid

Question 21

What is the management for acute asthma?

Answer 21

Oxygen (40-60%)
Nebulised (via spacer) B2-adrenoceptor agonist (e.g salbutamol or terbutaline)
Oral prednisolone or i.v hydrocortisone

Question 22

What management is added in a life-threatening attack?

Answer 22

Nebulised ipratropium
Subcutaneous B2-adrenoceptor agonist
I.V aminophylline, provided patient isn’t already receiving xanthine
Magnesium sulphate (i.v) used unlicensed

Question 23

What do NSAIDs do in asthma?

Answer 23

E.g aspirin, ibuprofen

Increase leukotriene production

Question 24

Why can’t B-blockers be used in asthma?

Answer 24

Block bronchial B2 adrenoceptors and cause bronchospasm
Applies to selective B1 antagonists
Used with caution in COPD