A chronic inflammatory disease of the airways involving many cells which leads to muscle spasm, mucus plugging, and oedema resulting in recurrent wheezing, cough, breathlessness and chest tightness
Acute attacks may be caused by URTI (eg. flu) and exposure to irritant substances, eg dust, exercise, cold
Causes
• Not known but associated with allergies, inherited and environmental factors
Clinical features
• No fever (if fever present, refer to Pneumonia, p77)
• Difficult breathing with chest tightness and may be use of accessory muscles. May not appear very distressed in severe attack
• Wheezing, rhonchi
• Cough - usually dry, may be intermittent, persistent or acute
Differential diagnosis
• Heart failure
• Other causes of chronic cough, eg. chronic bronchitis
• Bronchiolitis
• Bronchiectasis
Investigations
Diagnosis is mainly by clinical features
Specialized investigations:
Lung function: peak flow rate
Sputum: for eosinophilia, Gram stain for bacteria (when available)
If evidence of bacterial infection:
X-ray: chest
Blood: haemogram
3.1.1 Management of acute asthma attacks
• Regard each emergency consultation as being for acute severe asthma unless shown otherwise
• Failure to respond adequately at any time requires immediate referral to hospital
a) Adults and children >12
Uncontrolled asthma
Clinical features
• Speech normal
• Pulse <110 bpm
• Respiration <25 breaths/minute
• Peak flow >50% of predicted or best
Management
Treat as an out-patient
HC3
Give salbutamol 5mg by nebuliser or inhaler 2 puffs (200µg) every 10 minutes for a 30-60 minutes.
Monitor response 30 minutes after the dose
If peak flow 50-75% of predicted or best, or patient says s/he feels better, give:
prednisolone 30-60mg as single dose, or in 2-3 divided doses
and step up the usual treatment (see p62)
Alternatively, if peak flow >75% of predicted or best:
Step up the usual treatment (see p62)
Review within 48 hrs
- monitor symptoms & peak flow
- arrange self-management plan
- adjust treatment according to guidelines for chronic asthma (see p62)
Acute severe asthma
Clinical features
• Cannot complete sentences
• Pulse ≥ 110 bpm
• Respiration ≥ 25 breaths/minute
• Peak flow <50% of predicted or best
Management
Seriously consider hospital treatment if >1 of the above features are present
oxygen 40-60%
Give salbutamol 5mg by nebuliser or inhaler 2 puffs (200µg) every 2-5 minutes for 20 puffs
prednisolone 30-60mg single dose or hydrocortisone 200mg IV bolus stat
Monitor response 30 minutes after nebulisation
If any signs of acute asthma persist:
Refer for admission to hospital
While waiting for ambulance, repeat the salbutamol 5mg by nebuliser
or give aminophylline 250mg slow IV bolus
- but not if taking an oral theophylline
Alternatively, if symptoms have improved, respiration & pulse are settling and peak flow >50%:
Step up the usual treatment (see p62)
and continue with prednisolone
Review within 24 hrs
- monitor symptoms & peak flow
- arrange self-management plan
- adjust treatment according to guidelines for chronic asthma (see p62)
Life-threatening asthma
• Silent chest
• Cyanosis
• Bradycardia or exhaustion
• Peak flow <33% of predicted or best
Management
Arrange for immediate hospital referral and admission
While waiting for the ambulance:
Immediately give prednisolone 30-60mg single dose or hydrocortisone 200mg IV bolus stat
oxygen 40-60%
salbutamol 500 micrograms SC or aminophylline 250mg slow IV bolus
- but not if taking an oral theophylline
Stay with the patient until the ambulance arrives
Notes
• Patients with severe or life-threatening asthma may not be distressed and may not have all the clinical features listed; the presence of any should alert the clinician.
• If the patient says they feel very unwell, listen to them!
Do not give bolus aminophylline to any patient already taking an oral theophylline, eg. aminophylline
b) Children <12
Clinical features
Acute mild asthma attack
• Mild dyspnoea
• Diffuse wheezes
• Adequate air exchange
• Peak flow meter reading is ³80% of normal
Acute severe asthma:
• Too breathless to talk or feed
• Respiration: child<5 yrs: >50 bpm child ≥ 5 yrs: 40 bpm
• Pulse: child<5 yrs: >140 bpm child ≥ 5 yrs: 120 bpm
• Use of accessory muscles of breathing (young children)
• Peak flow ≤ 50% of predicted or best (older children)
Life-threatening asthma:
• Cyanosis
• Silent chest or poor respiratory effort
• Fatigue or exhaustion
• Peak flow < 33% of predicted or best (older children)
Management
Mild-moderate acute episode
Treat as an out-patient
HC3
salbutamol tablets
child:
<2yrs: 100 micrograms/kg
2-6yrs: 1-2mg
6-12yrs: 2mg
- only use tablets when inhaler or nebuliser solution are not available
or salbutamol inhaler 100 micrograms (1 puff) every 30 seconds
HC4
- repeat prn up to 10 puffs until symptoms relieved (preferably give doses using a large volume spacer, and face mask in the very young if available)
or salbutamol nebuliser solution 2.5mg by nebuliser
- if initial response is poor, repeat after 15 minutes
- review after every 3-4 hours and continue if necessary with the above dose every 3-4 hours
Review after 3-4 hours
If response is favourable, ie.
• Respiratory rate ↓
• Use of accessory muscles ↓
• Improved ‘behaviour’ pattern
Repeat salbutamol doses above every 3-4 hours (consider doubling the dose of any inhaled corticosteroid if the patient was taking this prior to the attack)
If salbutamol still required every 3-4 hours after 12 hours of treatment:
Give 1-3 day course of prednisolone:
child
<1yr: 1-2 mg/kg/day
1-4yrs: up to 20mg daily
5-15yrs: up to 40mg daily
If unresponsive or relapse within 3-4 hours:
Refer immediately to hospital
Increase frequency of salbutamol doses:
- give as often as required
Start prednisolone (doses as above)
Give high-flow oxygen via face-mask or nasal cannula
3.1.2 Management of chronic asthma
• Follow a stepped approach
- start at the step most appropriate to initial severity
• Rescue course
- give a 1-3 days ‘rescue course’ of prednisolone at any step and at any time as required to control acute exacerbations of the asthma at a dose of:
child <1 yr: 1-2mg/kg daily 1-5 yrs: up to 20mg daily 5-15 yrs: up to 40mg daily adult: 40-60mg daily for up to 3 days, then taper off during the next 4 days
• Stepping down
- review treatment every 3-6 months
- if control of asthma is achieved, stepwise reduction may be possible
- if treatment started recently at Step 4 (or contained corticosteroid tablets), reduction may take place after a short interval; in other patients 1-3 months or longer of stability may be needed before stepwise reduction can be done
• Always check compliance and inhaler technique before stepping up
a) Adults and children >5
Step 1: occasional relief bronchodilator
Inhaled short-acting beta2 agonist eg. salbutamol inhaler 1-2 puffs (100-200 micrograms) prn up to once daily
- move to Step 2 if more than this needed or there are night-time symptoms
or salbutamol tablets: 2-4mg as above
- only use if inhaler not available as less effective
Step 2: regular inhaled preventer therapy
salbutamol inhaler 1-2 puffs prn
plus regular standard-dose inhaled corticosteroid, eg. beclomethasone 100-400 micrograms every 12 hours
- higher dose may be needed initially to gain control
- doubling of the regular dose may be useful to cover exacerbations
Step 3: regular high-dose inhaled corticosteroids
salbutamol inhaler 1-2 puffs prn up to 2-3 hourly
- usually 4-12 hourly
plus beclomethasone (inhaler) 0.4-1mg every 12 hours
Step 4: regular corticosteroid tablets
salbutamol (as in Step 3)
plus regular high-dose beclomethasone (as in Step 3)
plus regular prednisolone 10-20mg daily after breakfast
b) Children <5
• If available, use a large-volume spacer for inhaler doses
Avoid oral corticosteroids in children below 12 years
Step 1: occasional relief bronchodilator
short-acting beta2 agonist (not more than once daily) eg. salbutamol inhaler 1-2 puffs (100-200 micrograms) - this is the preferred route as it is more effective and has less side-effects
or salbutamol tablets:
child <2: 100 micrograms/kg 2-5yrs: 1-2mg
Move to Step 2 if more than this needed or there are night-time symptoms
Step 2: regular inhaled preventer therapy
salbutamol prn (doses as in Step 1)
plus regular standard paediatric dose inhaled corticosteroid, eg. beclomethasone inhaler 50-100 micrograms (1-2 puffs) 2-4 times daily
- intial dose depends on age, weight and severity of asthma
- assess effect after 1 month and adjust the dose prn; if control not adequate, consider doubling the dose for 1 month
Step 3: increased-dose inhaled corticosteroids
salbutamol prn (doses as in Step 1)
plus regular high paediatric dose inhaled corticosteroid, eg. beclomethasone inhaler 100-200 micrograms (2-4 puffs) 2-4 times daily
Consider a short ‘rescue’ course of oral prednisolone
- see p61
Step 4: regular higher-dose inhaled corticosteroids + regular bronchodilator
salbutamol prn (doses as in Step 1)
plus regular higher-dose inhaled corticosteroid, eg. beclomethasone up to 2mg daily in divided doses
Consider:
- a short ‘rescue’ course of oral prednisolone (p61)
- nebulised salbutamol:
child >18 mths: 2.5mg up to 4 times daily (increase to 5mg/dose if necessary)
If there is suspicion of infection (fever, purulent yellow sputum), add 7-10 day course of an antibiotic:
amoxicillin 500mg every 8 hours child: 15mg/kg per dose or cotrimoxazole 480mg every 12 hours child: 24mg/kg per dose
Alternative in severe infection:
benzylpenicillin 1-2 MU IV or IM every 6 hours for 5 days child: 50,000 IU/kg per dose
Caution
Do not give drugs such as morphine, propranolol or other B-blockers to patients with (family history of) asthma as they cause worsening of respiratory problems
Do not give sedatives to children with asthma even if they are restless
Prevention
• Avoid precipitating factors, eg.
- cigarette smoking
- aspirin
- known allergens such as dust, pollens, animal skins
- exposure to cold air
• Exercise can precipitate asthma in children, advise them to keep an inhaler handy during sports and play
• Effectively treat respiratory infections
