• Ask about possible trigger factors, such as a recent upper respiratory tract infection.
• Ask about the type and duration of symptoms, what treatment has been started (if any), and whether treatment has improved symptoms.
• Assess the severity of the exacerbation:
• Look for signs of exhaustion (inability to complete sentences) and cyanosis (bluish lips or extremities).
• Examine the person's chest and record the respiratory rate, pulse, and blood pressure.
• Record the peak expiratory flow rate (if the person is old enough to comply) and use the best of three recordings to grade the severity of the attack on the basis of the person's best or predicted value:
• Moderate: more than 50–75%.
• Acute severe: 33–50%.
• Life-threatening: < 33%.
• Measure a person's oxygen saturation in room air using pulse oximetry (if available).
• Ask about depression, alcohol misuse, poor compliance with medication, social isolation and previous exacerbations as these factors will reduce the threshold for hospital admission.

In depth

• Admit all people with a life-threatening asthma exacerbation (peak expiratory flow rate [PEFR] usually < 33% best or predicted and/or oxygen saturation < 92%).
• Admit people with a severe asthma exacerbation (PEFR usually 33–50% best or predicted) who do not rapidly respond to initial treatment or who have a factor that warrants a lower threshold for admission.
• Admit people with a moderate asthma exacerbation (PEFR usually > 50% best or predicted) who have a factor that warrants a lower threshold for admission.
• The following factors should lower the threshold for admission:
• People under 18 years.
• Poor concordance.
• Person lives alone.
• Psychological problems such as depression, and alcohol or drug misuse.
• Physical or learning disability.
• Previous near-fatal attack or brittle asthma.
• Persistent exacerbation despite an adequate dose of oral corticosteroids before presentation.
• Presentation at night or in the afternoon.
• Pregnancy.

In depth