Acute asthma in children | Right Decisions

This content is from the BTS/SIGN British guideline on the management of asthma (SIGN 158), 2019.

The assessment of acute asthma in children under five can be difficult.
Intermittent wheezing attacks are usually triggered by viral infection and the response to asthma medication may be inconsistent. Prematurity and low birth weight are risk factors for recurrent wheezing.
The differential diagnosis of symptoms includes aspiration pneumonitis, pneumonia, bronchiolitis, tracheomalacia, and complications of underlying conditions such as congenital anomalies and cystic fibrosis.
This guideline is intended for children who are thought to have acute wheeze related to underlying asthma and should be used with caution in younger children who do yet have a considered diagnosis of asthma, particularly those under two years of age.
The guideline is not intended for children under one year of age unless directed by a respiratory paediatrician.
The guideline should not be used to treat acute bronchiolitis.

Clinical assessment

See algorithms summarising the recommended treatments for children presenting with acute or uncontrolled asthma in:

The table below details criteria for assessment of severity of acute asthma attacks in children.

Levels of severity of acute asthma attacks in children

(⁶³⁹)

Moderate acute asthma

Able to talk in sentences
SpO₂ ≥92%
PEF ≥50% best or predicted
Heart rate:
- ≤140/min in children aged 1–5 years
- ≤125/min in children >5 years
Respiratory rate:
- ≤40/min in children aged 1–5 years
- ≤30/min in children >5 years.

Acute severe asthma

Can’t complete sentences in one breath or too breathless to talk or feed
SpO₂ <92%
PEF 33–50% best or predicted
Heart rate
- >140/min in children aged 1–5 years
- >125/min in children >5 years
Respiratory rate
- >40/min in children aged 1–5 years
- >30/min in children >5 years.

Life-threatening asthma

SpO₂ <92% plus any one of the following in a child with severe asthma:

Clinical signs

Measurements

Exhaustion
Hypotension
Cyanosis
Silent chest
Poor respiratory effort
Confusion

PEF <33% best or predicted

Before children can receive appropriate treatment for an acute asthma attack in any setting, it is essential to assess accurately the severity of their symptoms.

The following clinical signs should be recorded:

Pulse rate
- increasing tachycardia generally denotes worsening asthma; a fall in heart rate in life-threatening asthma is a preterminal event
Respiratory rate and degree of breathlessness
- ie too breathless to complete sentences in one breath or to feed
Use of accessory muscles of respiration
- best noted by palpation of neck muscles
Amount of wheezing
- which might become biphasic or less apparent with increasing airways obstruction
Degree of agitation and conscious level
- always give calm reassurance.

Clinical signs correlate poorly with the severity of airways obstruction.⁶⁴⁰^-⁶⁴³ Some children with acute severe asthma do not appear distressed.

Decisions about admission should be made by trained clinicians after repeated assessment of the response to bronchodilator treatment.

Pulse oximetry

Accurate measurements of oxygen saturation are essential in the assessment of all children with acute wheezing. Oxygen saturation monitors should be available for use by all healthcare professionals assessing acute asthma in both primary and secondary care settings.

Consider intensive inpatient treatment of children with SpO₂ <92% in air after initial bronchodilator treatment.

Peak expiratory flow

PEF measurements can be of benefit in assessing children who are familiar with the use of such devices. The best of three PEF measurements, ideally expressed as a percentage of personal best, can be useful in assessing the response to treatment.

A measurement of <50% predicted PEF or FEV1 with poor improvement after initial bronchodilator treatment is predictive of a more prolonged asthma attack.

Chest X-ray

Chest X-rays rarely provide additional useful information and are not routinely indicated.⁶⁴⁴, ⁶⁴⁵

A chest X-ray should be performed if there is subcutaneous emphysema, persisting unilateral signs suggesting pneumothorax, lobar collapse or consolidation and/or life-threatening asthma not responding to treatment.

Blood gases

Blood gas measurements should be considered if there are life-threatening features not responding to treatment. Arteriolised ear lobe blood gases can be used to obtain an accurate measure of pH and PaCO2.⁵⁷⁸ If ear lobe sampling is not practicable a finger prick sample can be an alternative. Normal or raised PaCO2 levels are indicative of worsening asthma. A more easily obtained free flowing venous blood PaCO2 measurement of <6 kPa (45 millimetres of mercury) excludes hypercapnia.⁵⁷⁸

References

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