Asthma Flashcards
What is Asthma?
A chronic inflammatory condition of the airways that causes episodic exacerbations of bronchoconstriction.
What is Bronchoconstriction?
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.
What are the key factors of the airway obstruction?
Reversible airway obstruction that typically responds to bronchodilators e.g. Salbutamol.
Risk Factors of Asthma.
- Personal/Family History of Atopy.
- Antenatal Factors e.g. Maternal Smoking, RSV Infection in Pregnancy.
- Postnatal Factors e.g. Maternal Smoking, No Breastfeeding, Low Birth Weight.
- Exposure to Allergens, Air Pollution, ‘Hygiene Hypothesis’.
Atopic Triad (3).
IgE-Mediated Atopic Conditions :
- Allergic Asthma.
- Atopic Dermatitis (Eczema).
- Allergic Rhinitis (Hay Fever).
Typical Triggers of Asthma (7).
- Infection.
- Night-Time or Early Morning.
- Exercise.
- Animals.
- Cold/Damp Conditions.
- Dust.
- Strong Emotions.
Commonest cause of Occupational Asthma.
Isocyanates - spray painting, foam moulding using adhesives.
Clinical Presentation of Asthma (5).
- Episodic Symptoms.
- Diurnal Variability - worse at night.
- Dry cough & SOB.
- Bilateral Widespread ‘Polyphonic’ Expiratory Wheeze.
What does a wheeze related to coughs and colds suggest?
What does a unilateral wheeze suggest?
- Coughs/Colds : Viral Induced Wheeze.
- Unilateral : Focal Lesion/Infection.
Pathophysiology of Asthma.
- Bronchoconstriction.
- Mast Cell Degranulation.
- Increased Mucus Production.
BTS/SIGN Guidelines on Diagnosis of Asthma (3).
- Low Probability - Consider Referral and Investigating for Other Cause.
- Intermediate Probability - Perform Spirometry with Reversibility Testing.
- High Probability - Try Treatment.
NICE Guidelines on Diagnosis of Asthma (3).
- Assess at a ‘diagnostic hub’ to establish a diagnosis after investigating.
- 1st Line Investigations : Fractional Exhaled Nitric Oxide AND Spirometry with Bronchodilator Reversibility.
- 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.