Asthma

Question 1

What is the definition of asthma?

Answer 1

Chronic inflammatory disorder of airways characterised by bronchial hyperactivity to stimuli which leads to airways obstruction (can be irreversible)

Question 2

What changes occur in the bronchioles in someone with asthma?

Answer 2

SM contraction
SM hypertrophy= thickening of walls
BM membrane thickening
Mucous and exudate in lumen

Question 3

What are the 3 main causes of airway obstruction in asthma?

Answer 3

Inflammatory cell infiltration by TH cells, lymphocytes, eosinophils and mast cells
Mucus hypersecretion and mucus plug formation
SM contraction

Question 4

What changes occur microscopically in asthma?

Answer 4

Desquamated epithelial cells
Eosinophil membranes
Infiltration of inflammatory cells i.e. CD4 lymphocytes

Question 5

How is the hygiene hypothesis related to asthma?

Answer 5

Early life exposure to bacterial endotoxins switches off allergic response
I.e. lack of early exposure can lead to increase risk of developing asthma

Question 6

What are the main factors leading to the development of asthma?

Answer 6

Environmental
-asthma after 12= likely environmental cause

Genetic:

• Asthma before 12= genetic link
• FH has important role in asthma

Question 7

What is the trilogy of conditions referred to as atopy?

Answer 7

Allergic rhionitis
Asthma
Eczema

Question 8

What are the 2 types of triggers for asthma? Give examples of each.

Answer 8

Inducers= enhance inflammatory response

• allergens
• viral infection
• occupational exposure
• animal fur
• dust
• mould
• aerosols

Provokers= activate bronchospasm

• exercise
• cold air
• stress
• aspirin

Question 9

What are the classic presenting symptoms? What are the characteristics of these symptoms?

Answer 9

Episodic breathlessness (SOB)
Cough
Wheezing
Chest tightness

Variable and intermittent
Diurnal variation= worse at night
Associated with triggers

Question 10

What are clinical signs to look out for on examination?

Answer 10

Wheeze= polyphonic and expiratory

Hyperinflation (associate with longstanding or poorly controlled asthma)
-pronounced pectoral and SCM muscles due to increased use of accessory muscles for breathing

No wheeze and silent chest= life-threatening asthma

Question 11

How is the wheeze for asthma different from that associated with tracheal/subglottic stenosis?

Answer 11

Asthma

• polyphonic= due to multiple small airways being affected
• expiratory

Tracheal stenosis:

• monophonic= single tone due to narrowing of large airway
• inspiratory

Question 12

What are the components required for diagnosis of asthma?

Answer 12

Day to day peak flow variability 
Asthma symptoms 
Airway hyperresponsiveness 
Reversibility of airway obstruction 
i.e. >15% increase in FEV1 after single dose of SABA or several weeks of steroids

Question 13

How is a peak flow used to support the diagnosis of asthma?

Answer 13

Diurnal variation

-20% variation in PEF for >3/7 days

Question 14

How can spirometry be used to support a diagnosis of asthma?

Answer 14

Can show an obstructive pattern i.e. decrease forced expiratory volume in 1 second (FEV1)

Question 15

What are the possible differentials for asthma?

Answer 15

Upper airway obstruction
-can cause wheeze BUT it is monophonic

COPD
-irreversible

Tracheal tumour

GORD
-micro aspiration of acid= can cause inflammatory response in airways

Interstitial lung diease

HF

Pulmonary hypertension

Chronic thromboembolic disease

Bronchiectasis

Question 16

What are the non-pharmacological managements of asthma?

Answer 16

Smoking cessation
Weight reduction in obesity
Allergen avoidance in sensitised individuals

Question 17

How is asthma managed pharmacologically? What are the different classifications of drugs and their basic mechanism?

Answer 17

Step wise approach (most appropriate TX for severity) to gain early control

Selective Beta-2 agonist= RELIEVER (blue inhaler)
Eg= salbutamol + terbutaline
Mech= bronchodilation

Inhaled corticosteroids= PREVENTER (brown inhaler)
Eg= Beclometason + Fluticason + Budesonide
Mech= acts as anti-inflammatory

Long-acting beta-2 agonist= LABARs
Eg= Salmeterol + Foromoterol
Mech= used in combo with steroids on step 3 of asthma management

Leukotrienes receptor antagonist= ADD ON to inhaled steroids
Eg= Montelukast
Mech= target leukotrienes as a prophylaxis for asthma

Xantaine derivatives= ADD ON to relieve acute bronchospasm
Eg= IV aminophyline (specialist use only)
Mech= non-selective phosphodiesterase inhibitors to interfer with bronchial SM

Long acting antimuscarinics= LAMAs
Eg= Tiotropium
Mech= bronchodilators in severe asthma

Question 18

What are the 3 different levels of severity of acute severe asthma?

Answer 18

Moderate:

• increasing symptoms
• PEFR 50-75% of predicted or best

Severe: (any one of)

• PEFR 33-50%
• RR> 25
• HR>110
• inability to complete sentence in one breath

Life threatening:

• PEFR <33%
• Sats <92%
• PaO2 <8kPA
• cyanosis
• silent chest
• bradycardia
• hypotension
• exhasution
• confused
• coma

I.e CHEST
C= cyanosis 
H= hypotension 
E= exhaustion 
S- silent chest 
T- tachy/Brady/arrhythmia

Question 19

Why is it important to look at changes in CO2 levels in someone with severe asthma?

Answer 19

Severe asthma= CO2 normally low due to hyperventilation

Rising= life-threatening attack

Normal= patient is tiring i.e. unable to breath enough

Question 20

How is a patient with acute severe asthma managed?

Answer 20

Sit upright
High flow oxygen via non-rebreath mask
Salbutamol (5mg) + ipratropium (0.5mg) nebs
Steroids= 100mg IV hydrocortisone or 40mg PO prednisolone
Inhaled ipratropium bromide (SAMA) 500mg every 4-6 hrs via O2 driven neb
MgSO4= 2g IV
Inform ITU as may need to be intubated
Monitor ECG
-due to salbutamol increased HR

Question 21

Once a patient with severe acute asthma is stabilised, what can be done to monitor them?

Answer 21

PEFR every 15-30 mins

SpO2 maintained above 92%

ABG (if initial CO2 normal or high)

Oral prednilosone 15mg 1x day for 5 days

Neb salbutamol every 5 hrs

Question 22

What are the signs of asthma on CXR?

Answer 22

Hyper expansion with flattened hemi-diaphragms

Question 23

What are the possible adverse effects of using a high dose nebuliser SABA?

Answer 23

Tremor
tachycardia due to cross reaction with B1 receptor in heart
Decreased K+ due to action on Na+/K+ ATPase causing increased uptake of K+ by cells

Question 24

What are the possible adverse affects of using inhaled corticosteroids?

Answer 24

Oral candidiasis (oral thrush)
-can be due to poor technique and lack of use of spacer 

Osteoporosis

Growth suppression

Question 25

What are the common reasons for poor response to asthma treatment?

Answer 25

Non-adherence

• poor understanding
• trouble managing polypharmacy
• stress
• complicated regiment

Poor technique

Presence of inducers

Wrong diagnosis