Respiratory system - Asthma

Question 1

Define asthma.

Answer 1

A chronic disorder characterised by:

• Airway wall inflammation and airway wall remodelling
• Reversible airflow obstruction
• Increase in airway responsiveness to a variety of simuli

Question 2

What cells are present in the pseudo glandular-stage human lung that aren’t in the embryonic?

Answer 2

Smooth muscle apha actin positive cells in the airways

Question 3

What is the difference between normal lung and airway walls and those in wheezing disorders?

Answer 3

Asthmatic lung has increased ASM thickness, damaged epithelium and thickened RBM
Smokers lungs/premature birth lungs have all these characteristics plus loss of alveolar septa

Question 4

How are airway walls remodelled in asthma? What cells are involved?

Answer 4

Structural changes caused by chronic inflammation
Multiple cells and soluble mediators involved
Cytokines, leukotrienes, neutrophils, eosinophils, mast cells, growth factors for repair

Question 5

What are the triggers to ASM contraction?

Answer 5

Muscarinic agonists (ACH receptors)
Histamine
Cold air
Arachadonic acid metabolites e.g. prostaglandins, leukotrienes

Question 6

What does a flow volume loop for asthmatics look like?

Answer 6

Cut out expiratory flow, decreased volume, low PEFR and FEV1/FVC ratio. Reversible with salbutamol >12% increase in FEV1
Normal measurements do not exclude asthma

Question 7

Where is asthma most common?

Answer 7

Developed world. Incidence increases in populations who move from developing to developed countries (prevalence increasing)
5.4 mill in UK currently receiving treatment for asthma

Question 8

What can cause asthma?

Answer 8

Family risk
Sensitisation to airborne allergens (HDM, pollens) - air-pollution, tobacco smoke, fungal spores
Hygiene hypothesis
Allergic asthma
Viral-induced wheeze (most common under 5)
Aspirin sensitive asthma (adults only)
Occupational asthma

Question 9

How is asthma diagnosed?

Answer 9

Clinically. No standardised definition of the type, severity or frequency of symptoms, nor of the findings on investigation

Question 10

What are the recurrent symptoms of asthma?

Answer 10

Wheeze
Breathlessness
Chest tightness
Cough
Variable airflow obstruction

AHR and airway inflammation are components of the disease and their assessment aids diagnosis

Question 11

What is a wheeze?

Answer 11

High pitched, expiratory, musical sound
Originates in airways which have been narrowed by compression or obstruction
Variable intensity and tone in asthma (polyphonic)

Question 12

What is an asthmatic cough like?

Answer 12

Often worse at night (lack of sleep)
Exercise-induced
Dry
Wet cough = infection

Question 13

When might a asthmatic patient have trouble breathing?

Answer 13

Exercise
During acute exacerbations
Cold air

Question 14

What would an objective assessment of an asthmatic patient show?

Answer 14

Tachypnoea
Recession
Tracheal tug
Prolonged expiratory phase +/- wheeze

Question 15

What parts of a patients history help to diagnose asthma?

Answer 15

Onset and pattern of symptoms
Past medical history
Family history
Occupational history
Non-asthma drug history
Pets
Previous treatment

Question 16

How would you examine a patient you expect has asthma?

Answer 16

Chest - scars/deformities, hyper-expansion (barrel chest)
General health - eczema/hayfever, lethargy, can they talk?
Percussion - hyper-resonant
Auscultation - polyphonic wheeze

Question 17

What chest wall deformities might an asthmatic patient have?

Answer 17

Sternal (pectus) deformities are not common signs of asthma
Harrisons Suclus (in-drawing of costal cartilages is however common in children)

Question 18

What investigations are done in the clinic for asthma?

Answer 18

-Allergy testing - skin prick, blood IgE levels to specific aeroallergens
Exercise induced asthma
-CXR. Generally normal in the chronic situation (exclude other diseases esp pneumothorax during severe acute exacerbations)
-Trial of airflow reversibility
-Spirometry/Lung Function Tests - histamine or metacholine challenge
-Peak flow meter

Question 19

What is the management of asthma?

Answer 19

• Educate patents on correct recognition of symptoms, timely use of medication, services
• Primary prevention - stop smoking, cleaning, fresh air, breast feeding, exposure to allergens/triggers, weight
• Pharmacology - airway relaxants (relievers), anti-inflammatory agents (preventers)

Question 20

What airway relaxants and anti-inflammatorys may be used to treat asthma?

Answer 20

Airway relaxants:
- Beta 2 agonists (short and long acting)
- Muscarinic antagonists
-Theophylline/Aminophylline
Anti-inflammatory agents:
-Corticosteroids
-Leukotriene receptor antagonists

Question 21

What is the action of steroids in asthma?

Answer 21

decreases:
-secretion number of eosinophils
-T-lymphocyte cytokines
-mast cell number
-macrophage secretion and cytokines
-epithelial cell cytokines
-mucus secretion from mucus glands
-endothelial cell leakage
increases beta 2 adrenoceptors in airway smooth muscle

Question 22

What are the BTS guidelines for asthma?

Answer 22

Start treatment at the step most appropriate to initial severity
Achieve early control
Maintain control by stepping up and down treatment as necessary

Before initiating any new drug, check compliance and technique

Question 23

What are the sign so mild acute asthma?

Answer 23

Saturations >92% in air

Pulse 75% predicted

Question 24

What are the signs of moderate acute asthma?

Answer 24

Saturations >92% in air
Pulse <25
Speech normal
Wheeze
PEFR 75-50% predicted

Question 25

What are the signs of severe acute asthma?

Answer 25

Saturations 110
RR >25
Can't complete sentences
No wheeze
PEFR 35-50% predicted

Question 26

When is asthma life threatening?

Answer 26

Saturations <35% predicted

Rising or normal PCO2

Question 27

What is the ABC of acute asthma?

Answer 27

A - oxygen
B - continuous salbutamol and atrovent nebs
C - IV access - salbutamol, magnesium sulphate, aminophylline

Intubate and ventilate