Respiratory - Level 2 Flashcards
Definition of asthma?
- Respiratory condition associated with reversible airway inflammation and hyper-responsiveness
Classification of asthma?
o Extrinsic (Atopy) Allergens identified by positive skin prick to common inhaled allergens
o Intrinsic
No definitive external cause is identified and often develops in middle age
Pathology of asthma?
o Usually reversible either spontaneously or treatment
o 1. Airway narrowing
Smooth muscle contraction, thickening of airway wall by cellular infiltration and inflammation
Secretions within the airway
o 2. Inflammation
Mast cells, eosinophils, T cells, dendritic cells cause IgE production and release of histamine, prostaglandin D2, leukotriene C4
o 3. Remodelling
Hypertrophy and hyperplasia leading to more mucous secreting goblet cells
Epidemiology of asthma?
- 10-15% of people develop asthma in 2nd decade of life
- More common in developed world
- 15% of asthma induced at work
Risk factors of asthma?
- FHx of atopic disease
- Respiratory infections in infancy
- Tobacco smoke
- Low birth weight
- Social deprivation
- Inhaled particulates
Aetiology of asthma?
- Atopy
o Defined as people who readily develop IgE antibodies
o Genetic and environmental predispose to asthma
o Increased responsiveness of airways to stimuli – provocation tests induce a response (histamine)
Precipitating factors of asthma?
- House dust mite and its faeces
- Viral infections
- Cold air
- Exercise
- Irritant dust, vapours, fumes (cigarettes, perfume, exhaust)
- Emotion
- Drugs (Aspirin, beta-blockers)
Symptoms of asthma?
- Wheezing attacks
- SOB
- Chest tightness
- Cough (nocturnal)
- Sputum
Features characteristic of asthma?
- Intermittent and worse at night – diurnal variation
- Quantify exercise tolerance
- Disturbed sleep
- Often have atopy – hayfever, eczema
- Any pets, feathers, job
- Days per week of school/work
Signs of asthma?
- Tachypnoea
- Audible wheeze
- Hyperinflated chest
- Hyper-resonant percussion
- Decreased air entry
- Reduced chest expansion
Investigations of asthma - if suspected asthma?
- If <5 – treat based on symptoms and review child regularly, if still symptoms at 5, carry out objective tests
- If >5 and unable to perform objective tests – continue to treat and try redoing test every 6-12 months
Investigations of asthma in children 5-17 years - initial investigations to perform?
o Offer spirometry to all if diagnosis of asthma considered
FEV1/FVC <70% if positive tests for obstructive airway disease
o Bronchodilator Reversibility test
Consider if obstructive spirometry (FEV1/FVC <70%)
Positive test if >12% increase in FEV1
Investigations of asthma in children 5-17 years - when to diagnose asthma?
o Obstructive spirometry and positive BDR
o FeNO >35ppb and positive PEFR variability
Investigations of asthma in children 5-17 years - tests if diagnosis of asthma uncertain and what is a positive result?
o FeNO
If normal spirometry or obstructive spirometry with negative BDR test
35ppb or more is positive test
o Monitor PEFR variability for 2-4 weeks
If normal spirometry o robstructive spirometry with negative BDR test and FeNO >35ppb
>20% variability is positive test
o Refer for specialist assessment if obstructive spirometry, negative BDR and FeNO <35ppb
Investigations of asthma in children 5-17 years - when to refer to specialist?
o Refer for specialist assessment if obstructive spirometry, negative BDR and FeNO <35ppb
Investigations of asthma in children 5-17 years - when to suspect asthma?
o FeNO >35 with normal spirometry and negative PEFR variability
o FeNO >35 with obstructive spirometry but negative BR with no variability on PEFR
o Normal spirometry, FeNO <35 and positive PEFR
o Review diagnosis after 6 weeks of treatment by repeating any abnormal tests
Investigations of asthma in adults - objective tests to perform?
o FeNO
>40ppb is positive test
o Spirometry
FEV1/FVC <70% is positive result of obstructive spirometry
o Bronchodilator Reversibility Test (BDR)
If obstructive spirometry (FEV1/FVC <70%), positive result is >12% improvement of FEV1 with increase in volume of >200ml
Investigations of asthma in adults - diagnose asthma when?
o FeNO >40ppb with either positive BDR or positive PEFR variability or bronchial hyperreactivity
o FeNO between 25-39 and positive bronchial challenge test
o Positive BDR and positive PEFR variability irrespective of FeNO level
Investigations of asthma in adults - tests to perform if diagnosis uncertain?
o PEFR variability for 2-4 weeks (>20% variability is positive test)
If uncertainty and FeNO test and have either:
• Normal spirometry
• Obstructive spirometry with BDR positive but FeNO <39
o Direct bronchial challenge with histamine or methacholine if normal spirometry and either:
FeNO >40ppb with no PEFR variability
FeNO <39 with PEFR variability
PC20 (provoking concentration to induce 20% reduction in FEV1) of 8mg/ml or less is positive result
Investigations of asthma in adults - when to suspect asthma?
- Suspect Asthma if obstructive spirometry and:
o Negative BDR and either FeNO >40 or FeNO 25-39 and positive PEFR
o Positive BDR, FeNO 25-39 and negative PEFR
o Treat patients and review diagnosis after 6-10 weeks by repeating spirometry
Management of asthma - general advice?
- Weight loss
- Stop smoking
- Avoid triggers
- Annual flu vaccine
- Check inhaler technique and PEFR 2x a day
Management of asthma - medications - under 5s - step 1?
o SABA with 8-week trial of paediatric moderate dose ICS
If symptoms >3x per week, causing waking at night or not controlled on SABA alone
Management of asthma - medications - under 5s - step 2?
o After 8 weeks, stop ICS treatment:
If symptoms resolved then reoccurred within 4 weeks of stopping ICS – restart at paediatric low dose maintenance therapy
If symptoms resolved but reoccurred beyond 4 weeks after stopping ICS – repeat 8-week trial of paediatric moderate dose of ICS
Management of asthma - medications - under 5s - step 3?
o If unresolved on paediatric low dose maintenance therapy:
Add LTRA