Asthma Flashcards
(36 cards)
What is the definition of Asthma?
Chronic, reversible inflammation of airways and increased airway hyper-responsiveness
What is the prevalence?
-6.5% of the population is affected in England
-Incidence of asthma is higher in children than in adults
What is the pathophysiology of Asthma?
- Allergen which triggers the response which then presents an antigen.
- The presented antigen activates the thymus stromal lymphocytes and dendritic cells
- Dendritic cells present allergens to T-helper 2 (Th2) cells. This leads to its activation resulting in the release of the inflammatory cytokines: IL-4, IL-5, IL-13.
- Inflammatory cytokines activate B cells to produce IgE antibodies. IgE and mast cel form a complex; Mast cell-IgE complex.
- This complex leads to Mast cell sensitisation leading to the release of histamines.
- Mast Cell Degranulation → Releases histamine, leukotrienes, and prostaglandins, leading to bronchoconstriction and mucus secretion.
- IL-4, IL-5, IL-13 also Recruit eosinophils → Cause airway inflammation
What are the risk factors of asthma?
Weather
exercise
personal/family history of atopy
pre term birth
Sex ( more likely in males)
allergens exposure
environmental exposure (air pollution)
active/passive smoking
drugs (beta blockers, aspirin, NSAIDs)
What are the types of asthma?
Allergic/atopic asthma (e.g. pollen, pets, HDM
Eosinophilic asthma
Seasonal asthma
Occupational asthma
Exercise-induced asthma
How is asthma diagnosed?
- Variable PEF readings:
- PEF variability >20% over 2 weeks supports asthma diagnosis.
- Useful for work-related asthma (recorded at home & work). - Spirometry + reversibility:
- FEV₁/FVC <70% suggests obstruction.
- FEV₁ improvement by ≥12% AND 200mL after bronchodilator = Reversible Airway Obstruction (Asthma Likely). - Fractional Expired Nitric Oxide (FeNO):
- Assesses airway inflammation
- >25ppb - Mannitol challenge/ Bronchial Challenge Test:
- Used when diagnosis is unclear.
- FEV₁ drop >15% after inhaling methacholine/mannitol = Airway Hyperresponsiveness (AHR).
What does Spirometry show?
FEV1- Forced expiratory volume
FVC- Forced vital capacity
FEV1- amount of air exhaled in the first second of a forced breath
FVC- how much air you can exhale forcefully and completely
How is the FEV1 in restrictive and obstructive disorders?
FEV1 is reduced in obstructive disorders because there is airway resistance. It is also reduced in restrictive disorders because there is decreased compliance and elasticity so the lungs cannot force air out quickly
What does the FVC look like in obstructive compared to restrictive disorders?
FVC which is how much air you can forcefully exhale, is normal in obstructive disorders because there is a normal volume of air in the lungs. In restrictive disorders FVC is reduced because there is reduced lung expansion.
How does the FEV1/FVC ratio compare in obstructive vs restrictive disorders?
Obstructive Diseases → FEV₁/FVC < 70% which is decreased (Airflow obstruction, difficulty exhaling).
Restrictive Diseases → FEV₁/FVC ≥ 70% which is normal or high. (Reduced lung expansion, but no major obstruction).
What is restrictive vs obstructive disorders?
Obstructive Lung Disease:
Examples: Asthma, COPD (chronic bronchitis, emphysema), Bronchiectasis
🔹 Pathophysiology: Airway narrowing increases resistance to airflow, making it harder to exhale.
- have a Low FEV₁/FVC Ratio)
Restrictive Lung Diseases:
Examples: Pulmonary fibrosis, Sarcoidosis, Interstitial lung disease, ARDS
Pathophysiology: Lung stiffness (fibrosis) or weak muscles restrict lung expansion, reducing lung volumes
- Normal or High FEV₁/FVC Ratio)
What will the spirometry results show in asthma patients?
Spirometry will be normal is asthma patients if they are asymptomatic because asthma is a reversible condition .
How do you measure reversibility using spirometry?
- Perform the initial spirometry
- Give a bronchodilator e.g. salbutamol
- Perform another spirometry after 15mins
Looking for an improvement of 12%/200ml or more in FEV1
What is the Mannitol challenge ?
A bronchial provocation test used to diagnose asthma by assessing airway hyperresponsiveness (AHR).
How It Works:
1. Inhaled mannitol powder increases airway osmolarity, triggering bronchoconstriction in sensitive individuals.
2. FEV₁ is measured after each dose to check for airflow limitation.
Positive Test (Asthma Likely) → FEV₁ drops ≥15% at ≤635 mg of mannitol.
Negative Test (Asthma Unlikely) → No significant change in FEV
Used for exercise-induced asthma diagnosis.
Avoided in severe asthma (FEV₁ < 50%) due to bronchospasm risk.
What are the common symptoms of asthma?
Wheezing
breathlessness
coughing
tight chest
What are the clinical signs of asthma?
Wheezing on auscultation
Reduction in peak expiratory flow rate (PEFR)
Raised FeNO
What is the FeNO test?
A breath test that measures exhaled nitric oxide (NO) to assess eosinophilic airway inflammation in asthma.
How It Works:
Patient exhales slowly into a device.
Higher FeNO levels indicate airway inflammation, common in asthma.
What are the common categories of asthma therapy?
Inhaled corticosteroid/long-acting beta 2 agonist (ICS/LABA)
e.g. Symbicort, Fostair
Leukotriene receptor antagonist (LTRA)
e.g. Montelukast
Long-acting muscarinic antagonist (LAMA)
e.g. Tiotropium
Short-acting beta 2 agonist (SABA)
e.g. Salbutamol
Short-acting muscarinic antagonist (SAMA)
e.g. Ipratropium
What is ICS/LABA?
Inhaled Corticosteroid / Long-Acting Beta-Agonist is a combination inhaler used in the treatment of asthma and COPD. It includes:
ICS (Inhaled Corticosteroid) – Reduces airway inflammation (e.g., Beclometasone, Budesonide, Fluticasone).
LABA (Long-Acting Beta-Agonist) – Relaxes airway muscles for long-term bronchodilation (e.g., Salmeterol, Formoterol, Vilanterol).
What is the most common side effect of ICS use?
Oral sores/thrush, hoarseness, increased risk of pneumonia (COPD) → Prevent by rinsing mouth after use.
What is the most common side effect of beta-2 agonist use?
Tremor
Palpitations
What should we warn patients about prior to starting a LRTA?
Neuropsychiatric symptoms
What is the management of an acute asthma exacerbation?
- Increase the reliever doses of the ICS/formoterol inhaler (if being taken)
- OCS/IV steroids
- SABA
- Nebs (SABA+ SAMA)
- Oxygen (if indicated)
- Abx (if indicated)
- Escalation of care (if indicated)
What is the monitoring required during an acute asthma exacerbation?
- PF readings ( aim for >75% of best)
- Vital signs inc oxygen saturation
- auscultate the chest to assess for wheeze, if wheeze resolved can de-escalate therapy e.g stopping nebs
