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.