Laryngotracheobronchitis, also known as croup, is a type of upper respiratory tract infection usually resulting from a viral infection.
This infection is most common in younger children aged 6 months to 3 years old, who experience a characteristic barking cough, inspiratory stridor, and respiratory distress.
Croup is most likely to occur during the winter months. Early identification and treatment is important, as croup can range from a self-limiting illness to a life-threatening upper airway obstruction.
Croup is caused by a virulent upper respiratory tract infection that inflames the mucosa in the larynx. This causes airway obstruction resulting in turbulent airflow that produces an audible stridor.
This obstruction is linked to Poiseuille's law, which states that resistance to laminar airflow increases in inverse proportion to the fourth power of the radius. Thus, a small reduction in airway radius caused by inflammation and secretions can greatly raise resistance to airflow and increase the work of breathing.
Respiratory distress may worsen if the child becomes agitated or distressed, leading to higher airflow and pressure through the narrowed structures.
Croup can be caused by several viruses, including parainfluenza and respiratory syncytial virus (RSV0, as well as other viruses such as human coronaviruses, influenza, and rhinovirus. In very rare cases, bacteria such as Mycoplasma pneumoniae may be the culprit.
Risk factors for croup include:
Typical symptoms of croup include:
The clinical examination should focus on confirming the diagnosis and assessing severity. Care should be taken to avoid agitating the child, as this can worsen respiratory distress.
Most guidelines recommend minimal handling. Throat examination is not usually required, but may be done if the diagnosis is uncertain, except when epiglottitis is suspected.
A rapid ABCDE assessment should be performed to identify and treat any life-threatening features, such as impending respiratory failure or significant airway obstruction.
Typical clinical findings of croup include:
Further examination may be done once the situation is stabilized and no emergency treatment is needed. This may include ENT examination, an examination of the cervical lymph nodes, lung auscultation, and assessment for rashes.
There are various validated tools used to assess the severity of croup. Refer to local guidelines for more information. The Westley croup score, for example, can be used and is summarized below:
Important differential diagnoses to consider include the following:
Other differential diagnoses that should be considered include allergic reaction, airway injury, congenital airway anomalies, bronchogenic cyst, and early Guillain-Barré syndrome.
Croup is a clinical diagnosis and usually requires no investigations. If the diagnosis is in question and differential diagnoses need to be excluded, a lateral airway X-ray or chest X-ray may be useful.
A chest X-ray in croup will demonstrate the steeple sign due to subglottic narrowing.
A lateral airway X-ray in children may be considered to rule out foreign body inhalation.
Croup is an upper respiratory tract infection commonly caused by a viral infection (parainfluenza and RSV). It is commonly seen in children aged 6-36 months. Clinical features include a barking cough (often described as seal-like), stridor, and respiratory distress. The spectrum of severity varies from mild croup requiring no treatment, to life-threatening croup requiring nebulised adrenaline or endotracheal intubation.
A rapid ABCDE assessment should focus on confirming the diagnosis and assessing severity. The examination should not distress the child. Croup is a clinical diagnosis and requires no additional investigations. Important differential diagnoses to consider include upper airway abscess, epiglottitis, and foreign body inhalation.
Croup is a self-limiting illness. Management of croup aims to reduce the severity and avoid the need for intubation. Corticosteroids (e.g. dexamethasone) are the first-line pharmacological option to reduce the severity of symptoms. Treatment depends on the severity of the presentation.
Management of mild croup includes:
Management of moderate croup includes:
Discharge criteria include no stridor at rest, normal oxygen saturations, normal colour, normal activity, able to tolerate fluids orally, and caregivers understand when to return.
If the patient has worsened during observation, they may require nebulised adrenaline 5ml of 1:1000 and further observation.
Management of severe croup includes:
If children with severe croup require two or more doses of adrenaline, consider paediatric critical care review. An early review by the intensive care team is important as the patient may require intubation to protect the airway.
Indications for hospital admission include:
Additional factors to consider include young age, number of healthcare attendances, carer anxiety, or an inability for carers to bring the child back to the hospital in case of deterioration.
In most children, croup resolves within three days.
Complications are uncommon but can include secondary bacterial infections (including bacterial tracheitis, bronchopneumonia, and pneumonia), post-obstructive pulmonary oedema, pneumothorax, and pneumomediastinum.
In most cases, croup resolves within three days and complications are rare.
