CKS is no longer commissioned by the National Institute for Health and Clinical Excellence (NICE). NICE remains committed to providing a replacement service for CKS and is currently reviewing its options. In the meantime, although CKS content is now not being maintained, it still remains relevant and will continue to be made available. CKS content was generated under a programme of topic creation and update. To check if the topic you are viewing is current or out of date, please refer to the topic publication details by clicking on the 'How up-to-date is this topic?' link in the left hand menu on individual topic pages.
Asthma - Management
What assessment is recommended during an exacerbation of asthma?
- 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 any previous exacerbations. Together with the severity of the exacerbation, this will help to determine the risk of death and the need for hospital admission.
Clarification / Additional information
- Symptoms are a more sensitive measure than peak expiratory flow rate (PEFR) of the onset of an exacerbation, as the increase in symptoms usually precedes the deterioration in PEFR. Symptoms vary among individuals and age ranges. No symptom or sign alone (or together) is specific, and their absence does not exclude a severe exacerbation.
- Signs to look for and record include:
- Pulse rate (increasing suggests worsening asthma, whilst a decrease indicates a life-threatening situation).
- Respiratory rate and use of accessory muscles.
- Degree of wheeze (less apparent with increasing obstruction).
- Degree of agitation and consciousness.
- Peak expiratory flow rate is a more reliable indicator of severity than symptoms. Use a predicted PEFR value only if the person's recent (within 2 years) best PEFR is unknown. Ideally, use the person's own peak flow meter or a similar type.
- Pulse oximetry may not be available in primary care, especially for young children.
- When deciding to admit someone to hospital, assess the severity of this current exacerbation and also review the person's history. If they have any associated medical, behavioural, or psychosocial factors that are of concern, lower the threshold for admission.
- Use the criteria in Table 1 to grade and record the severity of an asthma exacerbation.
Table 1. Levels of severity of acute asthma exacerbation.
Level of severity | Criteria |
|---|
Near-fatal | Respiratory acidosis (increased arterial carbon dioxide) and/or requiring mechanical ventilation with increased inflation pressures |
Life-threatening | Any one of the following in someone with severe asthma: |
Peak expiratory flow rate < 33% of best or predicted Oxygen saturation < 92% Silent chest Cyanosis Feeble respiratory effort | Bradycardia Dysrhythmia Hypotension Exhaustion Confusion Coma |
Acute severe | Any one of: Peak expiratory flow rate 33–50% of best or predicted Respiration rate: 2–5 years old: 40 breaths/min 5–12 years old: 30 breaths/min > 12 years old: 25 breaths/min Pulse: 2–5 years old: 140 beats/min 5–12 years old: 125 beats/min > 12 years old: 110 beats/min Inability to complete sentences in one breath Use of accessory neck muscles (in children) |
Moderate asthma exacerbation | Increasing symptoms Peak expiratory flow rate > 50–70% of best or predicted No features of acute severe asthma |
Brittle asthma | Type 1: wide variability in peak expiratory flow rate despite intensive therapy (i.e. > 40% diurnal variation for > 50% of the time over > 150 days) Type 2: sudden severe attacks despite apparently well-controlled asthma |
Caution: people with severe or life-threatening attacks sometimes do not appear to be distressed and may not have all the features listed. Agitation and behavioural changes in a child may be a sign of hypoxia. Consider the occurrence of any feature as an alert for the presence of severe or life-threatening asthma [SIGN and BTS, 2009]. |
Basis for recommendation
- These recommendations are based on the British Guideline on the Management of Asthma: a national clinical guideline [SIGN and BTS, 2009]:
- Trigger factors: the evidence from small case-controlled studies shows that sensitization and exposure to allergens (house dust mites, cats, dogs) and respiratory viruses are independently and synergistically associated with asthma exacerbations [Green et al, 2002]. The role of atypical bacteria is much less certain [GINA, 2006].
- Symptoms: early intervention (via an action plan) at signs of a possible exacerbation is essential, as most (88–92%) asthma attacks severe enough to require hospital admission develop relatively slowly, over 6 hours or more. In one study, more than 80% developed over 48 hours [SIGN and BTS, 2009].
- Peak expiratory flow rate improves recognition of asthma severity and helps with decisions about management at home or in hospital. The most clinically useful value is peak expiratory flow rate measured as a percentage of the person's best [SIGN and BTS, 2009].
- Pulse oximetry can help diagnose life-threatening asthma if a person's saturation is below 92%. A prospective study (n = 1184) of children aged 2–17 years suggested that low oxygen saturation predicts hospital admission, but no specific cut-off value is sufficiently accurate for clinical decision making [Keahey et al, 2002].
© NHS Institute for Innovation and Improvement