History

The typical presentation of croup is in a preschool-aged child with a history of a recent onset of upper respiratory tract infection. The child subsequently develops a barking or seal-like cough, a hoarse voice and, if obstruction is severe enough, stridor. The stridor may initially be apparent only when a child is distressed, such as during crying. During crying or forced expiration the diameter of the upper airways physiologically narrows and, hence, stridor will manifest. Stridor, which is initially inspiratory, indicates obstruction at the laryngeal level or higher (i.e. upper airway). Expiratory stridor or biphasic stridor indicates more severe laryngeal obstruction or alternatively an obstruction occurring lower in the airway. The natural history of airway obstruction, when unmodified by steroids, is to increase slowly to peak over 24–48 hours. The airway compromise usually then resolves over a few days, although the laryngeal cough may persist longer.

Less common than infectious croup but usually more sudden in onset, older children may present with recurrent or spasmodic croup with no viral prodrome. This is thought to be allergic in origin. These children may have a history of atopy and suffer from asthma more than the general population. They should, however, be treated in the same manner as ‘viral’ croup. In the smaller child, particularly infants, problems with feeding, swallowing difficulties, and whether the child has been cyanosed should be ascertained.

It is important to enquire whether or not the child has had croup or other airway problems in the past and, specifically, whether the child has had any persistence of mild stridor in between acute attacks. This is important, as any child who has a pre-existing narrowing of the airway (infantile floppy larynx, laryngomalacia or other upper airway anatomical abnormalities) is more likely to proceed to severe obstruction with a superimposed acute obstruction. These children need to have a lower threshold for a period of observation as their obstruction may be more severe or persistent.

An immunisation history is important to check whether the child has had Hib vaccination if there is any suggestion that the condition could be epiglottitis; likewise, the very rare occurrence of diphtheria in the non-immunised.

Examination

Croup in children can generally be classified as mild, moderate, or severe (Table 6.7.1).

Table 6.7.1 Croup severity

Sign or symptom Mild Moderate or severe Stridor None or only if agitated Stridor at rest Respiratory rate Usually normal May be decreased Retractions None + to +++ Air entry Normal Normal to decreased Colour Normal May be pallor Cyanosis None Late sign only Conscious state Normal Restless or decreased

After Marks et al 2003.²

Most children with mild croup are not distressed and have only a barking cough with no stridor at rest or stridor audible only with physical activity, crying, or agitation. Crying causes physiological narrowing of the airway and will increase the respiratory distress. Hence the distressed, crying child’s obstruction will often defervesce by allowing the child to be cuddled in the parent’s arms. There may be signs due to viral illness, such as mild fever and nasal discharge. Children with mild cases can have their throats examined, but this should be deferred in more severe cases. A compromised but functioning airway should never be made worse by upsetting the child.

In more severe cases, the child may have a more pronounced stridor at rest. As airway obstruction progresses, increased work of breathing ensues and the child exhibits increasing substernal, intercostal, and subcostal retractions. Subtle signs of hypoxia causing altered consciousness may be reflected as anxiety or restlessness in a child. An obviously fatiguing child is a worrying sign. The child manifesting decreased air entry and respiratory effort, extreme pallor, and cyanosis requires immediate intervention.