asthma

Question 1

define asthma

Answer 1

chronic inflammatory condition of the airways that causes episodic exacerbations of bronchoconstriction

Question 2

describe the aetiology of asthma

Answer 2

unknown, more common in PMH/ FHx of atopy and children exposed to passive smoke

attacks - interaction between a susceptible host and an environmental trigger - pollen, allergens, URTI, cold air/ exercise

Question 3

define airway calibre

Answer 3

airway calibre is generated as a result of a balance between force generated by smooth muscle and opposing fibres

Question 4

describe control of bronchial calibre

Answer 4

controlled by a balence between:

sympathetic nervous system-> bronchodilation. decreases mucus secretion by beta 2 adrenoceptors

parasympathetic nervous system-> bronchoconstriction, increases mucus secretion by M3-receptors

Question 5

Describe non-atopic asthma

Answer 5

low level TH1 response to an antigen

typical triggers: infection, animal dander, cold/ damp, dust, diurnal variability - worse at night

IgG and macrophage involvement

Question 6

describe atopic asthma

Answer 6

strong TH2 response to an antigen

mast cells (initial asthma attack), eosinophil accumulation (late phase)

Question 7

what are the key characteristics of asthma resulting from long term inflammation (7)

Answer 7

reversible airflow obstruction via M3 receptors (parasympathetic) - leads to bronchoconstriction and increased mucus secretion

bronchial inflammation and hyperresponsiveness due to epithelial damage

airway remodelling - increase in number of goblet cells and hypertrophy

increased smooth muscle mass due to hyperplasia/ hypertrophy

oedema due to increase of interstitial fluid

epithelial damage - exposes sensory nerve endings

subepithelial fibrosis

Question 8

clinical presentation of asthma

Answer 8

episodic: diurnal variability -> typically worse at night

non-productive dry cough

dyspnoea

wheeze due to turbulent airflow

‘tight chest’

decreased exercise tolerance

Question 9

risk factors for asthma

Answer 9

PMH and FHx of atopy

Question 10

investigations for asthma

Answer 10

Hx and examination

spirometry

provocation testing - bronchospasm. can be exercise or histamine induced (children only)

diurnal peak flow variability

? reversability to inhaled salbutamol

Question 11

outline the long term management for asthma

Answer 11

1. SABA and ICS
2. SABA, ICS and LABA/ LAMA. If no response, remove LABA/ LAMA and increase ICS. If some response, continue LABA/ LAMA and increase ICS
3. add LRTA (leukotrinace receptor agonist)/ theophilline/ cromone -> all mast cell stabilizers
4. oral steroid and anti IgE/ anti IL-5/ anti IL-4 alpha

Question 12

outline the management for an acute exacerbation of asthma

Answer 12

OSHITMAn

O oxygen is hypoxaemic
S salbutamol nebulised
H hydrocortisone IV OR oral prednisolone
I ipratropium nebulised
T theophilline orally
M magnesium sulphate IV
An Anaesthetist to intubate

Question 13

outline the complications of asthma

Answer 13

an asthma attack (acute exacerbation)

compromised of immediate and delayed inflammatory reaction phases
immediate - bronchospasm
delayed - inflammatory reaction

Question 14

describe asthma as an immune imbalence in an atopic individual

Answer 14

type 1 hypersensitivity - more common in western countries

strong Th2 response, antibody mediated, includes IgE

Question 15

describe asthma as an immune imbalance in a non-atopic individual

Answer 15

low level Th1 response - cell mediated immunity including IgG and macrophages