Asthma severity

Question 1

Moderate acute asthma

Answer 1

Increasing symptoms
Peak flow > 50-75% best or predicted
No features of acute severe asthma

Question 2

Severe acute asthma

Answer 2

Peak flow 33-50% best or predicted
Respiratory rate ≥ 25/min
Heart rate ≥ 110/min
Inability to complete sentences in one
breath

Question 3

Life threatening acute asthma

Answer 3

Peak flow < 33% best or predicted
Arterial oxygen saturation (SpO2) < 92%
Partial arterial pressure of oxygen (PaO2) < 8
kPa
Normal partial arterial pressure of carbon
dioxide (PaCO2) (4.6–6.0 kPa)
Silent chest
Cyanosis
Poor respiratory effort
Arrhythmia
Exhaustion
Altered conscious level
Hypotension

Question 4

Near fatal acute asthma

Answer 4

Raised PaCO2 and/or need for mechanical
ventilation with raised inflation pressures