BTS/SIGN Asthma guidance

Latest revision 2019. See also asthma.

Diagnosis is about probability – high probability is recurrent episodes of cough, wheeze, breathlessness, chest tightness plus documented wheeze, atopic history, documented variable PEF or FEV1. Isolated episodic cough is not sufficient. Episodes typically triggered by viral infections, cold air, exertion, laughter or emotion. Start treatment, “typically” 6 weeks inhaled corticosteroids (ICS). If good response to treatment, then diagnosis is confirmed.

Diagnostic algorithm for asthma

If intermediate probability then spirometry with reversibility is preferred initial test for children old enough to do it (Grade D recommendation). If spirometry normal, then do challenge tests and/or Fractional exhaled nitric oxide (FeNO) measurement. For younger children, watchful waiting or trial of treatment [colour code suggests this is appropriate from age 1, but no advice given for under 1…].

FeNO has reasonable positive predictive value, but false positives in allergic rhinitis, rhinovirus and dietary nitrates, plus overlap in values between asthmatics and normal population (especially children).

Red flags –

  • Focal chest signs
  • Abnormal voice or cry
  • Failure to thrive
  • Vomiting
  • Wet/productive cough
  • Nasal polyps


Self management education, written personalized plan. Assess control – consider using Asthma Control Test (ACT) questionnaire or similar.

Assess risk of future attacks. Co-morbid atopic conditions, younger age, obesity, and exposure to environmental tobacco smoke are markers of increased risk (some of these strongly socioeconomically linked, of course).

Ask specifically about medication use and assess prescriptions. Explore attitudes to medication as well as practical barriers to adherence.

Not for routine house dust mite avoidance measures. Avoid smoking and second hand smoke.

Weight loss (including dietary and exercise programmes) for overweight and obese. Breathing exercise programmes can be offered as an adjuvant to pharmacological treatment for adults.


ICS are recommended preventer. An asthma attack in the previous 2 years, symptoms 3 days a week, or using reliever 3 days a week, or waking 1 night a week are indications. Give twice daily at least until good control established.

Start at dose appropriate for the severity of the disease. In mild to moderate asthma, no benefit in starting at high dose and weaning. In children, “reasonable” starting dose is Very Low (100mcg twice daily of Clenil or equivalent).

5yrs and over, if add-on is required then choice between inhaled long acting beta agonist (LABA) or leukotriene receptor antagonist (LTRA). Only then increase dose of ICS from very low (100mcg Clenil or equivalent twice daily) to low (200mcg twice daily).

For exercise induced symptoms, generally just a sign that inadequate control! But if otherwise well controlled then give inhaled short acting beta agonist immediately prior to exercise. Then choice between LRTA, LABA, cromoglicate or theophylline.

Acute Severe Asthma

Levels of acute asthma attacks in children
  • Sats under 92%
  • PEF 33-50% of best or predicted
  • Can’t complete sentences in one breath, or too breathless to feed
  • HR >140 (under 5), >125 (over 5)
  • RR>40 (under 5), >30 (over 5)

Life threatening defined as:

  • PEF <33%
  • Exhaustion, poor resp effort [tautology?]
  • Hypotension
  • Cyanosis
  • Silent chest
  • Confusion

Treat –

  • Oxygen
  • MDI plus spacer if mild/moderate
  • If refractory to beta agonist, add ipratropium 250mcg mixed into beta agonist [same dose for everyone]
  • “Consider adding 150mg magnesium sulphate to each neb in first hour if symptoms started <6hrs and presenting with sats <92%” [Recommendation based on MAGNETIC trial – no overall benefit but better Asthma Severity Score at 1 hour for this subgroup – see below] – 2.5ml of 250mmol/ml (1000mg made up to 16ml)
  • Give oral steroids early, dose by age.

Second line treatment –

  • Consider single IV bolus of salbutamol (15mcg/kg over 10mins)
  • Consider aminophylline for severe asthma unresponsive to maximal doses of bronchodilators and steroids.
  • Consider IV MgSO4 40mg/kg/d

Systematic review of IV Magnesium in children (2018) – pulmonary function improved, hospitalization and further treatment decreased. MAGNETIC trial of Magnesium nebs did not show a clinically significant improvement in mean asthma severity scores in children with acute severe asthma. Best clinical response was seen in children with saturations <92% at presentation and those with preceding symptoms lasting less than 6 hours [Lancet 2013].