Asthma Flashcards
Define asthma
Chronic, obstructive intermittent inflammatory airway disease characterised by reversible airway obstruction, airway hyper-reactivity and bronchial inflammation
What is the aetiology of asthma
Multiple gene associations + environmental exposure
Gene: ADAM 33, atopy, family history, dipeptidyl peptidase 10
Environment: dust mites, pollen, pets, cigarette smoke, viral RTI
What are the risk factors for asthma
Atopic history
Family history of atopic disease e.g. asthma, eczema, allergic rhinitis, allergic conjunctivitis
Respiratory infections in infancy
Prenatal exposure to tobacco smoke
Premature birth and LBW
Obesity
GORD
Male sex for pre-pubertal asthma and female sex for persistence of asthma from childhood to adulthood
What % of the population are affected by asthma
10% children, 5% adults
Prevalence increasing
What is the pathogenesis of asthma
Wall inflammation, thickening, tight smooth muscle
Early phase (1h): exposure to inhaled allergens in pre-sensitised individual → cross-linking of IgE Abs on mast cells → histamine, prostaglandin D2, leukotriene, TNF-alpha release → smooth muscle contraction, mucous hypersecretion, oedema, obstruction
Late (after 6-12h): eosinophil, basophils and neutrophil recruitment
What are the symptoms of asthma
SOB/dyspnoea/breathlessness
Cough (worse in the night or morning)
Wheeze
Chest tightness
triggers: recent RTI, exercise, allergens/irritants, cold weather, emotion/laughter
What is Samter’s triad
three conditions which commonly cluster together: asthma, nasal polyps and aspirin sensitivity
What are the differentials for asthma
Viral induced wheeze
Bronchitis
Bronchiectasis
Ciliary dyskinesia
Cystic fibrosis
Bronchiolitis
Croup
Foreign body aspiration
GORD
Pertussis
What are the signs of asthma on examination
Obs: tachypnoea
Height and weight
General: assess consciousness
Cardio
Resp:
- Expiratory polyphonic wheeze (multiple pitches and tones heard over different areas of the lung when the person breathes out)
- Tachypnoea
- Use of accessory muscles
- Prolonged expiratory phase
- Hyperinflated
What investigations should be done for asthma
<5yo: clinical diagnosis
5-16: Spirometry + BDR ± FeNO
>16: FeNO → spirometry + BDR ± PFV ± BC ± specialist diagnosis
Bedside: peak expiratory flow rate (PEFR) + variability (PFV) >20%
Bloods:
Other:
- Spirometry: FEV1/FVC ratio <70%
- Bronchodilator reversibility: improvement in FEV1 of >12% / >200mL increase in volume after SABA
- FeNO testing: >35ppb (measure of airway inflammation)
- Bronchial challenge: PC20 ≤8mg/mL (with methacholine or histamine challenge)
What are the features of a moderate asthma exacerbation
PEF 50-75% best or predicted
No signs of severe asthma
What are the features of a severe asthma exacerbation (>12yo)
PEF 33-50% of best or predicted
RR >25
HR >110
Inability to complete sentences in one breath
Accessory muscle use
What are the features of a life-threatening asthma exacerbation (>12yo)
PEF <33%
Low sats
Normal CO2
Cyanosis or confusion
Hypotension
Exhaustion
Silent chest
Tachycardia
What are the features of a near-fatal asthma exacerbation (>12yo)
Raised PaCO2
Requires mechanical ventilation
What is the management for a mild acute asthma exacerbation
Burst therapy
- Salbutamol (SABA) via spacer, 10 puffs total, one every minute, 5 tidal breaths per puff
- Repeat 10-20 minutes later according to response
- Discharge if better within 1 hour
- TAME: Technique, Avoid triggers, Monitor PEF, Educate
- Quadruple inhaled ICS for up to 2 weeks
- Follow up within 2 days of discharge (GP)
What is the management for a moderate-life-threatening acute asthma exacerbation
- ABCDE
- ADMIT TO EMERGENCY CARE (severe or worse)
- Aim for sats 94-98%, give oxygen if needed
- Salbutamol 2.5mg (2-5yo) or 5mg (>5) via nebuliser back to back given with 6L/min O2 over 30-60mins
- Ipratropium 500 micrograms (>5yo) or 250 micrograms (2-5yo) via nebuliser every 4 hours
- Steroids
a. PO prednisolone 50mg OD for 5 days
b. IV hydrocortisone 100mg every 6 hours (give 5 days dose) - IV magnesium sulfate
- Aminophylline if required (specialist)
- Ventilation/intubation, admit to ITU
What is the management for chronic asthma
- SABA reliever therapy - salbutamol inhaler
- ICS maintenance + SABA - beclemothasone/budesonide inhaler
- SABA + ICS + leukotriene receptor antagonist - montelukast PO
- ICS + LABA - formoterol, salmeterol e.g. symbicort, seretide
- MART (ICS + LABA in single inhaler) - Fostair
- Medium dose ICS + LABA ± TRA
- High dose ICS + LABA ± SAMA, LAMA, theophylline + seek specialist care
<5yo: if LTRA ineffective → refer to asthma specialist
What features suggest a need to step up asthma therapy
3 or more days a week with symptoms
using SABA >3x a week
Night time waking
what are the non-pharmacological aspects of asthma care
Baseline asthma status (asthma control Q)
Self-management education
Personalised asthma action plan (Asthma UK)
Up to date with vaccinations
Trigger avoidance
Inhaler technique education
Information on support (asthma UK)
Annual review: adherence, inhaler technique, side effects, control of asthma
How do you step down asthma therapy
ICS as maintenance therapy:
If controlled > 3 months, reduce ICS by 25-50% every 3 months
Stop entirely if the child has good control
Plan for self monitoring and annual follow up
What should follow up be for children with an acute asthma exacerbation
<48 hours, can be in GP
Review symptoms, check PEF
Check inhaler technique
Consider stepping up treatment
Educate on signs of exacerbation
Consider quadrupling ICS at the onset of attack and for up to 14 days in order to reduce risk of needing PO steroids
Prescribe a short course of PO prednisolone (3-7 days) if cannot increase ICS dose
What are the complications of asthma
Severe exacerbations
Airway remodelling
Growth retardation
Chest wall deformity
Recurrent infection
Pneumothorax
Impaired QOL
What are the side effects of asthma treatment
Salbutamol toxicity: shivering/tremor, vomiting, hypoK+, lactic acidosis, high glucose
ICS: oral/oesophageal candidiasis, dysphonia,
What is the prognosis for asthma
Life expectancy is similar to that of the general population
Many children improve as they grow older - male children are more likely to
Early onset = better prognosis
Chronic severe asthma: accelerated decline in lung function
When can a patient with an acute asthma exacerbation be discharged and how should they be followed up
Stable on ≥ 4 hourly bronchodilators for 12-24 hours
FEV1 should be > 75% predicted
(SpO2 > 94%)
Inhaler technique checked and recorded
- Follow up within 2 days of discharge (GP)
- Review in respiratory clinic in 4 weeks
