Initial assessment
The initial assessment of an adult with acute asthma is summarised in Table 2.
Spirometry is the lung function test of choice for assessing asthma severity during an acute episode (if the patient is able to perform the manoeuvre), and for monitoring the response to treatment.
Patients who are acutely distressed require immediate oxygen and short-acting beta2 agonist (SABA) before completing a full assessment.
| Table 2. Initial assessment of acute asthma in adults |
| Findings |
Mild |
Moderate |
Severe and life-threatening* |
| Physical exhaustion |
No |
No |
Yes
Paradoxical chest wall movement may be present |
| Talks in |
Sentences |
Phrases |
Words |
| Pulse rate |
< 100/min |
100-120/min |
More than 120/min† |
| Pulsus paradoxus |
Not palpable |
May be palpable |
Palpable‡ |
| Central cyanosis |
Absent |
May be present |
Likely to be present |
| Wheeze intensity |
Variable |
Moderate to loud |
Often quiet |
| PEF |
More than 75% predicted (or best if known) |
50-75% predicted (or best if known) |
Less than 50% predicted (or best if known) or less than 100 L per min# |
| FEV1 |
More than 75% predicted |
50-75% predicted |
Less than 50% predicted or less than 1 L |
| Oximetry on presentation |
- |
- |
Less than 90%
Cyanosis may be present** |
| Arterial blood gases (assay) |
Not necessary |
Necessary if initial response poor |
Necessary†† |
| Other investigations |
Not required |
May be required |
Check for hypokalaemia
Chest X-ray to exclude other pathology (e.g. infection, pneumothorax)
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*Any of these features indicates that the episode is severe. The absence of any feature does not exclude a severe attack.
†Bradycardia may be seen when respiratory arrest is imminent.
‡Paradoxical pulse is more reliable in severe obstruction. Its presence (especially if > 12 mmHg) can identify patients who need admission.13 Absence in those with severe exacerbations suggests respiratory muscle fatigue.
#Patient may be incapable of performing test.
** Measurement of oxygen saturation is required: many patients look well clinically and may not appear cyanosed despite desaturation.
††PaCO2 > 50 mmHg indicates respiratory failure. PaO2 < 60 mmHg indicates respiratory failure.
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Content Created (Thursday, 16 November 2006)
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Last Updated ( Thursday, 31 May 2007 )
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