Asthma

Question 1

What is Asthma?

Answer 1

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

Question 2

What is Bronchoconstriction?

Answer 2

Smooth muscles of the bronchi contract, due to hypersensitivity of the airways, causing a reduction in the diameter of the airways - narrowing causes an obstruction to airflow.

Question 3

What are the key factors of the airway obstruction?

Answer 3

Reversible airway obstruction that typically responds to bronchodilators e.g. Salbutamol.

Question 4

Risk Factors of Asthma.

Answer 4

1. Personal/Family History of Atopy.
2. Antenatal Factors e.g. Maternal Smoking, RSV Infection in Pregnancy.
3. Postnatal Factors e.g. Maternal Smoking, No Breastfeeding, Low Birth Weight.
4. Exposure to Allergens, Air Pollution, ‘Hygiene Hypothesis’.

Question 5

Atopic Triad (3).

Answer 5

IgE-Mediated Atopic Conditions :

1. Allergic Asthma.
2. Atopic Dermatitis (Eczema).
3. Allergic Rhinitis (Hay Fever).

Question 7

Typical Triggers of Asthma (7).

Answer 7

1. Infection.
2. Night-Time or Early Morning.
3. Exercise.
4. Animals.
5. Cold/Damp Conditions.
6. Dust.
7. Strong Emotions.

Question 8

Commonest cause of Occupational Asthma.

Answer 8

Isocyanates - spray painting, foam moulding using adhesives.

Question 11

Clinical Presentation of Asthma (5).

Answer 11

1. Episodic Symptoms.
2. Diurnal Variability - worse at night.
3. Dry cough & SOB.
4. Bilateral Widespread ‘Polyphonic’ Expiratory Wheeze.

Question 12

What does a wheeze related to coughs and colds suggest?

What does a unilateral wheeze suggest?

Answer 12

• Coughs/Colds : Viral Induced Wheeze.

- Unilateral : Focal Lesion/Infection.

Question 13

Pathophysiology of Asthma.

Answer 13

1. Bronchoconstriction.
2. Mast Cell Degranulation.
3. Increased Mucus Production.

Question 14

BTS/SIGN Guidelines on Diagnosis of Asthma (3).

Answer 14

1. Low Probability - Consider Referral and Investigating for Other Cause.
2. Intermediate Probability - Perform Spirometry with Reversibility Testing.
3. High Probability - Try Treatment.

Question 15

NICE Guidelines on Diagnosis of Asthma (3).

Answer 15

1. Assess at a ‘diagnostic hub’ to establish a diagnosis after investigating.
2. 1st Line Investigations : Fractional Exhaled Nitric Oxide AND Spirometry with Bronchodilator Reversibility.
3. Diagnostic Uncertainty - Further Investigations : Peak Flow Variability (Diary of Several Measurements Daily for 2-4 Weeks) and Direct Bronchial Challenge Test with Histamine or Methacholine.

Question 16

Diagnosis of Occupational Asthma.

Answer 16

Observe reduced peak flows during the working week with normal readings when not at work.

Question 17

What is Spirometry?

Answer 17

A test to measure the volume and flow of air during exhalation and inhalation to categorise respiratory disorders as either obstructive (to airflow) or restrictive (to lungs).

Question 18

What is the Spirometry picture in Asthma? (4)

Answer 18

1. FEV1 is significantly reduced.
2. FVC is normal.
3. FEV1 : FVC is less than 70%.
4. Reversibility Testing : Adults - Improvement in FEV1 of 12% or more or increase in volume of 200ml+.
5. Raised TLCO - Transfer Factor.

Question 19

What is the rationale of FeNO testing? (3)

Answer 19

1. Nitric oxide is produced by 3 types of NOS (Nitric Oxide Synthase).
2. 1 type is iNOS (Inducible NOS) which tends to rise in inflammatory cells like eosinophils.
3. Levels of NO correlate with levels of inflammation.

Question 20

FeNO Results.

Answer 20

> 40ppb in adults is diagnostic of asthma.

Question 21

Management of Asthma (4).

Answer 21

Stepwise-Ladder :

1. Start at most appropriate step, based on severity of symptoms.
2. Review at regular intervals based on severity and assess inhaler technique and adherence.
3. Step up/down (every 3 months) based on symptoms (reduce steroid dose by 25-50% at a time).
4. Aim : Achieve no symptoms/exacerbations on the lowest dose and number of drugs.

Question 22

NICE Guidelines Management of Asthma.

Answer 22

1. SABA.
2. Low-Dose ICS.
3. LRA.
4. LABA (continue only if good response).
5. MART - Maintenance and Reliever Therapy.
6. Titrate ICS to Moderate-Dose.
7. Titrate ICS to High-Dose or Oral Theophylline or Inhaled LAMA.
8. Refer to specialist.

Question 23

BTS/SIGN Guidelines Management of Asthma (7).

Answer 23

1. SABA.
2. Low-Dose ICS.
3. LABA (continue only if good response).
4. Trial of LRA, Oral B2 Agonist, Oral Theophylline or Inhaled LAMA.
5. Titrate ICS to High-Dose.
6. Refer to specialist.
7. Oral Steroids.

Question 24

Doses of Steroids in Adults.

Answer 24

1. Low - Less than 400mcg.
2. Moderate - 400mcg-800mcg.
3. High - More than 800mcg.