• Croup is a viral infection of the upper airways, AKA viral laryngotracheobronchitis
• The virus causes inflammation in the laryngeal mucosa, as well as hyperaemia and oedema. All of this leads to narrowing of the airway in the subglottic area
• Just small reductions in the airway diameter can drastically reduce airflow and children can very rapidly deteriorate.
• The most common cause is parainfluenza virus in about 75% of cases. Other viruses that can cause croup include adenovirus, RSV, measles, coxsackie virus, rhinovirus, influenza A+B
• Most commonly affected age group is 6 months – 3 years

Signs and Symptoms

• Onset is usually over 1-2 days with initial mild cough and coryza, there may or may not be fever but it is unusual for a child with croup to have persistent high fevers.
• Barking cough that sounds like a seal – once you’ve heard it you won’t forget it!
• Inspiratory stridor – the volume of the stridor may decrease with increasing narrowing and obstruction of the airway.
• Increased work of breathing
• Hoarse voice
• Worse at night

Important Questions for your History:

• Ask about the onset of illness – if very sudden whilst playing unsupervised could be an inhaled foreign body
• Are they feeding okay?
• Any high temperatures?
• Have they had croup before? Some children are prone to recurrent croup and may need different management
• Birth history. If ex-preterm were they intubated and ventilated? These children are prone to subglottic stenosis which also causes stridor
• Has the stridor been present since birth? This could lead you more towards thinking about laryngomalacia or a vascular ring as the cause.
• Are immunisations up to date? The most worrying differential is epiglottitis caused by Haemophilus influenzae B (vaccinated against with the 6 in 1 vaccine at 8, 12 and 16 weeks, and again at 1yo)

On Examination:

• It is very important to remember that in a child with a degree of upper airway obstruction and stridor, try not to upset them. NEVER examine ENT. This is because acute distress can cause deterioration of an already compromised airway
• If the child is very distressed the most important things are to listen to the chest, measure oxygen saturations and observe work of breathing. You can use these observations to formulate a Westley Croup score [1] (this is a scoring system for rating the severity of croup and helps inform your management plan). If the child is extremely distressed then don’t listen to the chest
• Listen for stridor, is it present at rest or only when agitated?
• Listen for that classic cough
• Observe for signs of increased work of breathing (subcostal / intercostal recession, sternal recession, tracheal tug, abdominal breathing, nasal flaring, head bobbing, grunting)
• There may also be paradoxical breathing in severe distress. As a child has a very compliant chest wall this looks different to adults. They compensate for narrowing of the airway by increasing work of breathing as above. This raises intrathoracic pressure and the rate of airflow through the airway. As the thoracic pressure increases, when the child breathes in their chest wall collapses and their abdomen sticks out. Paradoxical breathing is not an effective form of respiration for long and children tire quickly leading too respiratory failure.
• If the child is “toxic” looking, drooling, has a high fever and is unimmunised this is more likely epiglottitis, and you should be much more worried

There are several different scoring systems for croup. The one I have come across most regularly is the Westley Croup score, although you should mainly rely on your own clinical judgement

Differentials

• Epiglottitis is a bacterial infection caused by HiB – it often occurs in unimmunised children and presents with severe pyrexia, drooling and a very “toxic” / septic looking child, they usually don’t have a cough. If you suspect epiglottitis, you should call a senior and call an anaesthetist ASAP. These children often need intubating.
• Inhaled foreign body – History will usually be of very sudden onset stridor, often preceded by a choking / coughing episode and no preceding coryzal illness. A chest x-ray would be helpful in diagnosing this whilst x-rays are not helpful in croup. An x-ray in a child who has inhaled a foreign body would show a hyperinflated and lucent affected lung on expiration (although can be normal in 35% of cases) [2]
• Pharyngeal abscess– presents with high temperatures and stridor and drooling, you may find a neck mass on examination and there will be neck stiffness and trismus.
• Angioedema – can be allergic, hereditary or idiopathic. If allergic there would usually be a preceding history of allergen exposure and an urticarial rash.
• Subglottic stenosis can occur due to iatrogenic damage to the airways from multiple intubations – more common in preterm babies, doesn’t usually cause a cough
• Laryngomalacia is essentially a floppy larynx that if severe can cause stridor at rest and increased work of breathing, as well as failure to thrive. This is usually present from birth or a few weeks old and is not sudden in onset. The stridor can be worse when feeding and lying flat.
• Vascular Ring – A congenital defect where there is abnormal development of the aorta / surrounding vessels and the trachea and oesophagus can be completely encircled by these. Presents with stridor, cough, difficult feeding. Stridor improves by extending the neck.

Management

You can use the Westley croup score to guide your management.

The most important part of your management is to keep the child comfortable, don’t perform a thorough examination and absolutely do not try to cannulate them. If they have an oxygen requirement you can give wafting oxygen (have the care giver hold a facemask with 5-15L oxygen running through near the child) until anaesthetic / ENT help arrives.

The gold standard of management is 0.15mg/kg dexamethasone as a STAT dose

If they have vomited the dex or spat it out (which happens ALL the time) you can give a 2mg budesonide neb.

Dexamethasone can start to have an effect within 30 minutes of oral administration, (although studies have disagreed on this and some state it can take up to 4 hours).

When the croup is very severe and the child is cyanotic the best action would be to try to keep the child calm, turn off alarms on machines, dim the lights etc, attempt to give dexamethasone at 0.6mg/kg, run an adrenaline neb through 15L oxygen and call anaesthetics or ENT. If you work in a hospital where anaesthetics are on the paediatric crash bleep no one would be angry if you put out a crash call in this scenario.

If a child has needed dex + adrenaline but then improves, they should be admitted to observation and may need regular doses of dex for 1-2 days.

Evidence Base:

• A prospective study undertaken in Taiwan from 2012-2014 reviewed the efficacy of the Westley Croup score for predicting severity and outcome of children with croup seen in A+E. They found that patients with a Westley score of <2 could be safely discharged without observation and none of these patients re-presented. Those with a score of >5 need admission to hospital for observation and further treatment. [3]
• A systematic review was undertaken in 2013 by Johnson DW to review the effects of different croup treatments. This found that in moderate to severe croup, IM / oral dexamethasone, nebulised adrenaline and nebulised budesonide all reduced symptoms compared to placebo. Furthermore, nebulised budesonide is as effective as oral dexamethasone at reducing symptoms but when they are used together the efficaciousness of treatment is equal to using either drug on its own. Lastly dexamethasone at a dose of 0.15mg/kg can be as effective as a dose of 0.6mg/kg. There is no evidence to support the use of humidification for croup. [4]
• There have been studies reviewing the use of heliox (a mixture of helium and oxygen) in the treatment of moderate to severe croup but it does not seem to be superior to current management options. [5]

References and Further Reading

Written by Dr Rebecca Evans Paediatric ST3