Acute asthma Flashcards
(19 cards)
How common is asthma?
7% of the UK population
Thought to affect 300M people worldwide
Who is affected by acute asthma?
- People with brittle asthma
- Any patient with asthma may develop acute asthma with the presence of certain triggers (infection, allergen exposure)
What causes acute asthma?
- Airway hyper-reactivity (excessive narrowing) in response to allergens/other triggers
- Atopy (propensity to produce IgE)
- Inhalation of allergen is followed by early (type I) and late phase responses (type II)
- Early asthmatic reaction (reaches peak at 20m)
- Followed by late asthmatic reaction (6-12 hours later)
- Very complex inflammatory reaction (mainly eosinophilic)
- Re-modelling of the airway - wall is thickened by oedema, cellular infiltration, increased smooth muscle mass and glands
- Chronic re-modelling leads to fibrosis, fixed narrowing
- Mucus plugging is a common feature of acute severe asthma
What risk factors are there, and how can they be reduced?
- Genetic susceptibility: atopy
- Exposure to allergens: dust mite, pet dander, fungal spores, feathers, smoke - avoidance
- Outdoor pollutants (triggering rather than initiating): SO2, NO2, particulates, ozone
- Cofactors: infections, smoking, diet (i.e. breastfeeding), drugs (beta-blockers, NSAIDS)
What is the presentation of acute asthma?
- Acute deterioration in lung function and increases airway inflammation
- Most attacks are characterised by a deterioration over hours to days, but can have no warning with brittle asthma
What symptoms should you look out for?
- Dyspnoea
- Chest tightness
- Cough
- Diurnal pattern
What signs may the patient have on examination?
- Increased RR
- Increased HR
- Wheeze
- Evidence of reversible airway obstruction - reduced FEV1 (
What other conditions might present in a similar way?
Children: inhaled foreign body, cystic fibrosis
Adult: Bronchial carcinoma, cardiac failure, COPD
How would you investigate this patient?
- ABG
- Spirometry - reversibility test: >15% increase in FEV1 following administration of brochodilator, measurement of FEV1 and FEV1/FVC
- Peak expiratory flow - >20% diurnal variation on >3 days per week for 2 weeks
- FEV1
What would you tell the patient and how would you explain the condition to them?
- Asthma is a common condition that affects the airways. The typical symptoms are wheeze, cough, chest tightness, and shortness of breath.
- Symptoms can range from mild to severe.
- Treatment usually works well to ease and prevent symptoms.
- Treatment is usually with inhalers. A typical person with asthma may take a preventer inhaler every day (to prevent symptoms developing), and use a reliever inhaler as and when required (if symptoms flare up).
- Caused by inflammation in the airways
- Explain what can make asthma worse
How do you think the patient and/or family might be affected by the diagnosis? Will it affect their ability to work/care for themselves?
- Time will be needed for adjustment
- In most cases treatment prevents loss of work/need for care
What questions are they likely to have?
- Is it fatal? (rarely)
- What caused it (unknown, complex and multifactorial)
- Will I have it forever? (approx 1/2 children grow out of asthma)
- How do I use my medication?
What pharmacological treatments would you discuss with the patient? What are the risks and benefits?
Acutely:
- nebulised salbutamol 5mg 6-12 times daily
- high flow 02
- Prednisolone 40mg PO or 200mg hydrocortisone IV
- repeat salbutamol+ipratropium bromide 500 ug
- consider IV Mg sulphate 1.2-2.0g over 20m or aminophylline
- Fluids and electrolytes (esp. K+)
Chronically:
- Short-term beta2 agonist (i.e. salbutamol) PRN
- Regular preventer therapy - daily inhaled steroid 400-800mg
- Add inhaled long-acting beta2 agonist if needed
- benefit = continue
- no benefit = increase steroid
- Addition of 4th drug if needed: leukotriene receptor antagonist (montelukast or zafirlukast), theophylline (inhibits leukotriene synthesis), beta2 agonist PO
Benefits - symptomatic control/relief, prevention of exacerbations
Risks - all medications have side-effects (e.g. theophylline - seizures), might develop tolerance to bronchodilators and need to take more drugs
What non-pharmacological treatments would you discuss with the patient? What are the risks and benefits?
- Avoidance of triggers
- Hypoallergenic bedding
- Removal of pets
Will not relieve/control attacks
What surgical treatments would you discuss with the patient? What are the risks and benefits?
None currently available on the NHS
What other healthcare professionals may be involved in their care?
- Asthma nurse
- Physiotherapist
- Occupational therapist
What are the signs of near-fatal asthma?
Respiratory acidosis
What are the signs of acute severe asthma?
Any one of:
- peak expiratory flow rate 33–50% of best or predicted
- respiration rate:
- 2–5 years old: 40 breaths/min
- 5–12 years old: 30 breaths/min
- > 12 years old: 25 breaths/min
- pulse:
- 2–5 years old: 140 beats/min
- 5–12 years old: 125 beats/min
- > 12 years old: 110 beats/min
- inability to complete sentences in one breath
- use of accessory neck muscles (in children)
What is brittle asthma?
Type 1: wide variability in peak expiratory flow rate despite intensive therapy (i.e. > 40% diurnal variation for > 50% of the time over > 150 days)
Type 2: sudden severe attacks despite apparently well-controlled asthma
