Management of acute asthma in adults
Initial assessment
Moderate acute asthma
PEF >50–75% best/predicted
no features of acute severe asthma
Acute severe asthma
PEF 33–50% best/predicted
RR ≥25/min
HR ≥110/min
inability to complete sentences in one breath
Life-threatening asthma
PEF <33% best/predicted
SpO₂ <92%
PaO₂ <8 kPa
‘normal’ PaCO₂ (4.6–6.0 kPa)
Altered conscious level
exhaustion
arrhythmia
hypotension
cyanosis
silent chest
poor respiratory effort
Near-fatal asthma
Raised PaCO₂
requiring mechanical ventilation
with raised inflation pressures
ADMISSION
Admit patients with any feature of a severe asthma attack persisting after initial treatment
Aim of oxygen therapy is to maintain oxygen saturation of 94–98%
Undertake arterial blood gas ABG if oxygen saturation <92% or other features of life-threatening asthma
Chest X-ray is not routinely recommended
FIRST-LINE TREATMENT
β₂ agonist Nebuliser + Oxygen + Steroids (prednisolone 40–50 mg daily until recovery for 5 days)
SECOND-LINE TREATMENT
Single dose of IV magnesium sulphate (1.2–2 g IV infusion over 20 minutes)
TRANSFER TO ITU
• requiring ventilatory support
• with acute severe or life-threatening asthma, who is failing to respond to therapy, as evidenced by:
deteriorating PEF
persisting or worsening hypoxia
hypercapnia
ABG analysis showing acidosis
exhaustion, feeble respiration
drowsiness, confusion, altered conscious state
respiratory arrest
DISCHARGE
Patients whose PEF >75% best/predicted one hour after initial treatment may be discharged from ED
FOLLOW UP (ADULTS)
Inform GP within 24 hours of discharge from ED or hospital admission following an asthma attack.
Keep patients who have had a near-fatal asthma attack under specialist supervision indefinitely.
A respiratory specialist should follow up patients admitted with a severe asthma attack for at least one year after the admission.