Asthma Flashcards
What is the GINA 2015 definition of asthma?
Asthma is a heterogeneous disease (aka reversible), usually characterised by chronic airway inflammation.
It is defined by the history of respiratory symptoms such as wheeze, chest tightness and dry cough that vary over time and in intensity, together with variable expiratory airflow limitation
How is asthma classified?
Extrinsic asthma
1) Most frequently in atopic individuals: allergic asthma
• Positive skin-prick reactions to common inhalant allergens (e.g. dust mite, animal dander, pollen, fungi)
• Often accompanied by eczema, allergic rhinitis
• Commonly starts between 3-5 years old, worsens /improves during adolescence (hence some individuals have childhood asthma only)
2) May also be non-atopic: non-allergic asthma
• Occupational agents (e.g. toluene disocynate) – occupational asthma
• Intolerance to NSAIDs (e.g. aspirin, given B blocker for concurrent hypertension /angina thereby blocking protective effect of endogenous adrenergic agonists)
• Asthma with obesity 🡪 due to compressive force of fat causing small airway Dz
Intrinsic asthma: late onset asthma
• Usually starts in middle age (usually female)
• No identifiable allergen
• Possible triggers: anxiety, stress, exercise, cold, smoke etc.
Asthma
- Age of 1st onset
- Smoking
- Symptoms
- Pattern of Sx
- FHx
- PMHx
- CXR
- CT thorax
- sputum histo
- Childhood is likely: Virtually all dx > 40 yo are female
- Smoking not significant
- Symptoms: wheeze, chest tightness, cough, dypsnea
- Nocturnal/early morning*, intermittent
- +ve Fam Hx
- PMHx: Atopy
- CXR: Normal in steady state, Hyperinflation** only seen during exacerbations
- CT thorax: Normal in steady state, Mosaic*** in exacerbations
- Sputum histo: Eosinophilic (but neutrophilic variant exists)
COPD
- Age of 1st onset
- Smoking
- Symptoms
- Pattern of Sx
- FHx
- PMHx
- CXR
- CT thorax
- sputum histo
- > 40 yo
- Smoking: >20 pack years
- Symptoms: wheeze, chest tightness, cough, dypsnea
- Progressive pattern of symptoms
- no Fam Hx
- no PMHx
- CXR: Hyperinflation
- CT thorax: Emphysematous
- Sputum histo: Neutrophilic
What is the relevant history to ask in a patient with asthma?
> 1 of: CARDINAL SYMPTOMS OF ASTHMA: wheeze, SOB, chest tightness, dry cough
Symptoms are intermittent and variable: aka reversible
Diurnal Variation: often occur or are worse at night or on waking
Precipitants: often triggered by
- Environmental: smoking, haze, dust, pets
- Cold air, cold drinks
- Exercise (↑RR 🡪 ↓ warming of air 🡪 irritates airways)
- Drugs: β-blockers, COX inhibitors
- Symptoms often occur with or worsen with URTI
Ask also about
- Home environment: any pets, 2nd hand smoke
- Job
- PMHx & FHX for atopy
Signs of severity: Asthma Control Test
If chronic Hx: Compliance, Control (ACT), Complications (Hospital Visits)
What are signs present in asthma patients during episodes?
- Expiratory Wheeze 🡪 If wheeze prolongs and encroach into inspiration = sign of severity!
- Episodic SOB
- Tachypnoea
- Tachycardia
- Use of accessory muscles of respiration
- Prolonged expiration – sign of obstructive disease 🡪 air unable to leave hence prolonged expiration (will also see in COPD patient)
- Hyperinflated chest – increased AP diameter, hyper-resonant percussion
Ascultation: Bilateral expiratory wheeze (or rhonchi)
What is the differential diagnosis of asthma in patients without airflow obstruction?
- Chronic cough syndromes (>3 weeks)
- Hyperventilation syndrome
- Vocal cord dysfunction
- Rhinitis
- Gastro-oesophageal reflux
- Cardiac failure
- Pulmonary fibrosis
What is the differential diagnosis of asthma in patients with airflow obstruction
Important: COPD, Bronchiectasis
Less common: Inhaled Foreign Body, Lung Cancer. Will cause a fixed obstruction hence a monophonic wheeze
Least Common: Large Airway Stenosis, Sarcoidosis, Obliterative Bronchiolitis (in GvHD)
What is the diagnostic criteria of asthma?
SIGN OF OBSTRUCTION (FEV1/FVC < 0.7) + Any 1 of the 5 below is sufficient to DIAGNOSE ASTHMA!
- We generally do (1) or (2)
- We proceed to other tests if we still suspect asthma however pt has failed (1) or (2)
- Also peak flow meter is easily manipulated!
1) !! Spirometry with significant reversibility:
- Increase in FEV1 ≥12% AND >200ml after administration of bronchodilator
- Increase in FEV1 >12% AND >200ml from baseline after 4 weeks of anti-inflammatory treatment
- The above conditions show that the obstruction is reversible with medication!
2) Peak Expiratory Flow (PEF) with significant reversibility:
- Improvement of 60L/min (or ≥20% of pre-bronchodilator PEF) after inhalation of bronchodilator
- Increase in PEF by >20% from baseline after 4 weeks of anti-inflammatory treatment
- More commonly used to monitor rather than diagnose due to its limitations
3) PEF chart at home showing significant diurnal variation (2 weeks):
- >20% with thrice daily readings or >10% with twice daily readings
4) Positive exercise challenge test
- 4-6 mins of exercise at 80% MPHR (max. predictable heart rate)
- Followed by serial spirometry post-exercise
- Cutoff: Fall in FEV1 of >10% and >200ml from baseline
- Best of 3 PEF measurements with highest two within 40L/min
5) Methacholine challenge test / Bronchoprovocation testing
- Useful to diagnose asthma in patients with normal baseline airflow → hence spirometry & reversibility tests are not enough for Dx
- Must also be substantial post-challenge FEV1 recovery → indicates this is Hypersensitivity (aka in asthma → not constant and irreversible like in COPD
- Normal PC20 = ≥16mg/mL
- Borderline hyper-responsiveness = 16.0 – 4.0mg/mL (still considered negative)
- Mild bronchial hyper-responsiveness = 1-4mg/mL (positive test!)
How would you monitor a patient’s asthma control?
- Symptomatic asthma control: using Asthma Control Test (ACT) score
• 20-25 = controlled
• 16-19 = partially controlled
• 5-15 = not controlled - Lung function (spirometry/PEF)
- Asthma attacks, oral corticosteroid use and time off work
- Inhaler technique
- Adherence (look at prescription refill frequency)
- Bronchodilator reliance (prescription refill frequency; >4 puffs a day or >1 canister a month)
- Possession of and use of a self-management plan/personal action plan
What is the non pharmacological management of asthma?
- Smoking cessation
- Weight reduction
- Vaccination
- Trigger avoidance – dust
- Patient education
- Appropriate inhaler technique
What is the step 1 and 2 of asthma therapy?
Daily:
- Low dose ICS (Beclomethasone dipropionate, budenoside)
- Leukotriene Receptor Antagonists (monteleukast)
As needed
- Low dose ICS- formeterol
- Low dose ICS whenever SABA inhaler is used
Reliever: SABA inhaler (not needed when using ICS- formoterol or MART). Do not use SABA monotherapy for asthma
What is the step 3 of asthma therapy?
Daily:
- Low dose ICS- LABA
- Low dose ICS + LTRA
- Medium dose ICS
Maintenance and Reliver therapy
- Daily low dose ICS- fomoterol + as needed low dose ICS formoterol
Reliever: SABA inhaler (not needed when using ICS- formoterol or MART). Do not use SABA monotherapy for asthma
What is the step 4 of asthma therapy?
Daily:
- medium dose ICS- LABA
- medium ICS + LTRA
- high dose ICS
Possible adjustments to daily preventer options above
- add LTRA to medium dose ICS- LABA or high dose ICS
- increase high dose ICS- LABA or high dose ICS + LTRA
- Add tiotropium
Maintenance and Reliver therapy
- Daily medium dose ICS- fomoterol + as needed low dose ICS formoterol
Possible adjustments to MART
- Add LTRA to daily medium ICS- formoterol
- Add tiotropium to daily medium ICS- formoterol
Reliever: SABA inhaler (not needed when using ICS- formoterol or MART). Do not use SABA monotherapy for asthma
What is the step 5 of asthma therapy?
Daily:
- medium dose ICS- LABA
- medium ICS + LTRA
- high dose ICS
Possible adjustments to daily preventer options above
- add LTRA to medium dose ICS- LABA or high dose ICS
- increase high dose ICS- LABA or high dose ICS + LTRA
- Add tiotropium
Maintenance and Reliver therapy
- Daily medium dose ICS- fomoterol + as needed low dose ICS formoterol
Possible adjustments to MART
- Add LTRA to daily medium ICS- formoterol
- Add tiotropium to daily medium ICS- formoterol
Reliever: SABA inhaler (not needed when using ICS- formoterol or MART). Do not use SABA monotherapy for asthma
Add on treatment with asthma biologic agents or low dose OCS
- Add tiotropium mist (LAMA – long acting muscarinic antagonist)
- Anti-IgE treatment (eg omalizumab)
- Anti-IL5 (eg: mepolizumab)
- LTRA – leukotriene receptor antagonist
- PO theophylline
- Last Resort: PO Prednisolone – low dose oral corticosteroids (≤7.5mg/day prednisolone equivalent)
