Asthma Flashcards
Define asthma.
Chronic inflammatory airways disease characterised by variable reversible airway obstruction, airway hyper-responsiveness and bronchial inflammation.
Define viral induced wheeze.
Inflammatory airways disease caused by a viral infection and is considered to be a precursor to asthma.
What are the risk factors for asthma?
Genetic factors: Positive family history of asthma or atopy.
Environmental triggers: Passive or active smoking, URTIs, exercise, cold weather, inhalant allergies (house dust mite/pollens/moulds/pets) and food allergens.
What is the pathogenesis of asthma?
Acute phase (within minutes): Contact with exacerbating factor (cigarette smoke, inhalant or food allergen or viral infection) leads to airway receptor hyper-responsiveness and narrowing of airways.
L_ate phase (onset after 2–4 hours, effect may last up to 3–6 months):_ Persistent bronchoconstriction secondary to vicious cycle of inflammation, oedema and excess mucous production.
Summarise the epidemiology of asthma.
Prevalence: 10–15%. Age: 80% of asthmatic children are symptomatic by the age of 5. M: F, 2:1; equalises in adulthood.
Distribution: Viral-associated wheeze/recurrent wheezy bronchitis. Higher in urban areas and in children of low socio-economic status families.
What are the presenting symptoms of asthma?
- Breathlessness
- Wheeze
- Non-productive cough (productive if there is superimposed infection)
- Chest pain
- Trouble sleeping
- 2–3 years: Nocturnal cough, wheezing during exercise with URTIs.
- <5 years: Non-productive cough may be the only symptom, often worse at night and in the morning (diurnal variation).
What are the signs of asthma?
Respiratory: End-expiratory wheeze, recession, use of accessory muscles, tachypnoea, hyper-resonant percussion note, diminished air entry, hyperexpansion, Harrison sulcus (anterolateral depression of thorax at insertion of diaphragm).
Peak flow: Useful in >5 years of age; use as baseline (predicted best) and as determinant for efficacy of treatment.
What are some appropriate investigations for asthma?
In acute asthma attacks skip to management.
- Bloods: FBC, CRP, U&Es. ABG/VBG/CBG – Respiratory distress, pH and lactate toxicity.
- PEF
- Sputum culture or NPA
- CXR
- Lung function tests – spirometry (conducted after 5 years of age to measure FEV1: FVC ratio).
What are the features of a moderate asthma attack?
PEFR 50-75% best or predicted
Speech normal
RR <25/min
Pulse <110bpm
What are the features of a severe asthma attack?
PEFR 33-50% best or predicted
Can’t complete sentences
RR >25/min
Pulse >110bpm
What are the features of a life-threatening asthma attack?
PEFR <33% best or predicted
Oxygen sats <92%
Silent chest, cyanosis or feeble respitatory effort
Bradycardia, dysrythmia or hypotension
Exhaustion, confusion or coma
When should antibiotics be used in an acute asthma attack?
If infective exacerbation is suspected
What is the first-line treatment for an acute asthma attack?
Call for help
- High-flow oxygen
- Burst therapy:
- Nebulised salbutamol with spacer x3
- Ipatropium bromide x2
- Prednisolone x 1
- Consider adding 150mg MgS04 if sats are lower than 92%.
What is the second-line treatment for an acute asthma attack?
IV bolus
- IV salbutamol
- IV hydrocortisone
- IV Magnesium sulphate
What is the third line treatment for an acute asthma attack?
IV infusion (salbutamol aminophylline)
Consider theophylline/aminophylline
Consider intubation
What is the first step in chronic treatment for an asthma patient? (Newly diagnosed asthma)
Short-acting beta-agonist (SABA)
What is the second step in chronic treatment for an asthma patient?
SABA + Paediatric low-dose inhaled corticosteroid (ICS)
When should the second step of management be consider when treating an asthmatic patient?
Not controlled on previous step
OR
Newly diagnosed asthma with symptoms >=3/week or night time waking
What is the third step in chronic treatment for a patient with asthma?
SABA + Paediatric low dose ICS + Leukotriene receptor antagonist (LTRA)
What is the fourth step in chronic treatment for asthma patients?
SABA + Paediatric low-dose ICS + Long acting beta-agonist (LABA)
Remove LTRA if is has not helped, in contrast to adult guidelines
What is the fifth step in chronic treatment for chronic patients?
SABA + Maintenance and reliever therapy (MART) including paediatric low-dose ICS
Remove ICS/LABA
What is the sixth step in chronic treatment for asthma patients?
SABA + paediatric moderate-dose ICS MART
OR
Consider switching MART for a fixed dose of moderate-dose ICS and a separate LABA
What is the seventh step in chronic treatment of asthma patients?
SABA + one of the following options:
- Increase ICS to paediatric high-dose, either as part of a fixed-dose regime or as a MART
- A trial of an additional drug (for example theophylline)
- Seeking advice from a healthcare professional with expertise in asthma
What is maintenance and reliever therapy (MART)?
A form of combined ICS and LABA treatment in which a single inhaler, containing both ICS and a fast-acting LABA, is used for both daily maintenance therapy.
MART: Formoterol – ICS and fast-acting LABA
What are the different doses for corticosteroids?
- Low dose: <200 mcg
- Moderate dose: 200-400 mcg
- High dose: >400 mcg
What is the discharge criteria for asthmatic patients?
Patients can be discharged when stable on 3–4-hourly inhaled bronchodilators. Peak flow 75% of predicted best, and O2 saturations >94%.
Education: On adherence to medication, recognition of acute attacks, emergency protocol, maintaining normal activities.
What is the management for a viral induced wheeze?
Episodic viral wheeze: Montelukast is recommended first line and should be started the first sign of a viral cold.
Multi-trigger wheeze: Inhaled corticosteroids or Montelukast trial for 4-8 weeks. If symptoms reoccur reduce treatment to the lowest level but may have to consider asthma diagnosis.
Can use inhaled bronchodilator. Need to confirm diagnosis of asthma before using oral steroids.
What are the complications associated with asthma?
Decreased linear growth rate due to poorly controlled asthma more usual than from over prescription of inhaled steroids, chest wall deformity, recurrent infections, status asthmaticus can be fatal.
One-third of deaths occur under the age of 5 years.
What is the prognosis of asthma?
Asthma often remits during puberty and many children are symptom free as adults, especially those who have mild asthma and are asymptomatic between attacks, or who develop asthma at >6 years. Rates of admission and mortality in asthma have decreased since the early 1990s.
