Asthma Flashcards
What is asthma?
Widespread narrowing of peripheral airways, varying in severity over short periods of time
What is the pathophysiology of asthma?
- Irritation
- Degranulation of mast cells
- Histamine
Contraction of smooth muscle, increase blood vessel permeability, increase bronchial secretions, attracts WBCs
- Chemotactic factors, leukotrienes, prostaglandins and major basic protein released
Inflammation - Bronchi mucosa swells and smooth muscle contracts
- Goblet cells in alveoli secrete mucus in respnse to irritation
- Narrows lumen
- Plugs smaller airways
What are the main symptoms of asthma?
- Wheeze
- Coughing
- Phlegm
- Dyspnoea
- Nasal polyps
What are the risk factors for asthma?
- Recent upper respiratory tract infection
- Positive family Hx of asthma
- Allergen exposure
- Atopic Hx
- GORD
- Obesity
What would you look for in a history to diagnose asthma?
- Symptoms
- Exacerbating factors
- Family/ Past medical Hx of exacerbating factors
What might you find on examination of a patient with asthma?
- Can be normal
- Expiratory polyphonic wheeze on chest auscultation
Has multiple pitches and tones heard over different areas of the lung when the person breathes out
What is the test for airway inflammation?
Fractional exhaled nitric oxide (FeNO)
What is a positive FeNO result?
- Adult : ≥ 40 ppb
- Children : ≥ 35 ppb
What can decrease FeNO?
Smoking
What are the tests for lung function?
- Spirometry
- Bronchodilator reversibility (BDR)
- PEFR
What is a positive spirometry result?
FEV1/FVC ratio <70%
What type of airway disease is asthma?
Obstructive
What does brochodilator reversibility aim to show?
Reversibility of airway obstruction to a short-acting bronchodilator
What is a positive bronchodilator reversibility test result?
- Improvement of FEV1 by ≥ 12%
- Increase in volume of 200ml
What is PEFR?
The maximal rate that a person can exhale during a short maximal expiratory effort after full inspiration
How do you predict PEFR?
Using a patients sex and height
When would you ask a patient to measure PEFR for 2-4 weeks?
- Normal spirometry result
- Obstructive spirometry result and FeNO ≤ 39 ppb
- Negative bronchodilator reversibility
What is an airway hyperreactivity measure?
Direct bronchial challenge test with histamine or methacholine
What is a positive direct bronchial challenge test?
PC20 value ≤ 8mg/ml
When patients present with symptoms for the first time, what other investigations would you order and why?
- CXR
- FBC
To exclude other differentials
What happens if after treatment symptoms control remains poor?
- Step up the treatment ladder
OR - Review diagnosis after 6-10 weeks
Do not rule out other diagnoses
What are asthma triggers?
- Cold weather
- Dust
- Allergens - Tree pollen
Exercise - Infections
- Stress/anxiety
What is a reliever inhaler?
Blue SABA inhaler
Relieves symptoms when they occur
What is a preventer inhaler?
Brown inhaled corticosteroid (ICS) inhaler
Used everyday to decrease inflammation and sensitivity of the airways
What happens to peak flow after a preventer inhaler is started?
- Peak flow improves
- Less variation between peaks and troughs on a graph
- Overall improvement
What is the advice given to people with exercise-induced asthma?
SABA
- Used shortly before exercise
- May be helpful for 2-3 hours
How long to LABAs last for?
Up to 12 hours
What drugs should be avoided in asthma?
- Aspirin
- NSAIDs
Ibuprofen
Naproxen - Beta-Blockers
How is asthma managed in primary care?
- Individual self-management programme
- Yearly asthma review
- Advice on smoking cessation
- Advice on exercise
What questions would you ask in the yearly asthma review as a GP?
- In the last month/week have you had difficulty sleeping due to your asthma?
- Have you had your asthma symptoms during the day?
- Has your asthma interfered with your usual daily activities?
What vaccinations must asthmatics get?
- Flu vaccine
Can prevent severe respiratory infections
Can prevent further inflammation of airways
Can prevent triggering of asthma attacks - Pneumococcal vaccine
Childhood immunisation now
People at high risk of infection get 23-valent pneumococcal polysaccharide vaccine
How can people with asthma monitor their symptoms?
Regular PEFR readings
How do you check an inhaler is working?
- Shake inhaler
- Check that the mouthpiece is not obstructed
- Squirt twice
What does SBAR stand for?
SBAR handover
- SITATUON
- BACKGROUND
- ASSESSMENT
- RECOMMENDATION
What is the atopic triad?
Eczema, allergies and asthma
What drugs can still be used in pregnancy for asthma?
Beta2-adrenergic agonists and inhaled steroids
Can prednisolone be used to treat an asthma attack in a pregnant woman?
Yes
- Benefit outweighs risk
How can anaesthetic potentially trigger an asthma attack?
- Bronchodilation is controlled by sympathetic innervation (T2-T4)
- Anaesthetic blocks the sympathetic NS
Is spinal or general anaesthetic safer in a patient with asthma?
Spinal
- More localised
