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Croup (acute laryngotracheobronchitis) is an upper airways disease that is most common in children aged between 6 months to 3 years. It usually presents with difficulty in breathing, fever, stridor and a seal or dog-like barking-cough on the background of a coryzal illness. Parainfluenza virus is the most common causative organism
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Parainfluenza
QuestionChoice
Bordetella is the causative agent in pertussis (whooping cough). This is a bacterial infection that is rarer than croup due to effective vaccination. Pertussis can present with an inspiratory gasp; however, the high-pitching rasping sound described in the question is more suggestive of stridor
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Bordetella pertussis
QuestionChoice
Rhinovirus is a well-recognised cause of croup; however, it is less common than parainfluenza
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Rhinovirus
QuestionChoice
RSV can cause croup; however, parainfluenza is more common. RSV is the most common causative organism in bronchiolitis
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Respiratory syncytial virus (RSV)
QuestionChoice
Mycoplasma is a rare cause of croup
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Mycoplasma pneumoniae
QuestionComment
Is the only reason this isn't bronchiolitis is that he has a high pitched rasping sound on inspiration?
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Also somewhat out of the peak age bracket for it? I know things aren't that exact in real life but this is quesmed
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Inpatient Syndrome
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# Summary
 

Croup (also known as acute laryngotracheobronchitis) is a common childhood infection characterised by a harsh barking cough and inspiratory stridor. It is usually mild and self-limiting, however, some cases may cause severe respiratory distress requiring hospitalisation and supportive treatment. Parainfluenza viruses are the commonest causes, but the diagnosis is a clinical one and as symptoms such as stridor can worsen if the child is distressed, investigations should only be done if necessary. Oral steroids should be given to all children; in moderate to severe cases nebulised adrenaline, supplementary oxygen and airway support may be indicated.
 

# Definition
 

Croup, or acute laryngotracheobronchitis, is an upper respiratory tract infection that in most cases has a viral aetiology. Key symptoms include a barking cough, hoarse voice and inspiratory stridor. 

#  Epidemiology
 

Croup commonly affects children aged from 6 months old to 3 years old, with the peak incidence at 2 years. It is uncommon after the age of 6.

Similar to other viral infections, it is commonest in the autumn and winter months and is linked to parainfluenza epidemics. 

#  Aetiology
 
The commonest cause is the parainfluenza virus. Other viral causes include adenovirus, respiratory syncytial virus (RSV), rhinovirus and influenza.
Rarely, bacteria can cause croup (e.g. Mycoplasma pneumoniae).

The pathophysiology involves infection and resulting inflammation of the subglottic and laryngeal mucosa which causes partial obstruction of the airways leading to respiratory distress and stridor.

# Signs and Symptoms

- The prodromal phase of coryzal symptoms, fever and a non-specific cough usually lasts 12-72 hours.
- Characteristic symptoms of croup such as the harsh barking cough, hoarse voice or cry and inspiratory stridor then develop - these tend to be worse at night.
- In severe cases, children may become drowsy and lethargic, or conversely more agitated.
- The usual course of disease is resolution of symptoms within 48 hours (up to a week at most).

On examination, look for the following red flags that may indicate impending respiratory failure:

- Signs of respiratory distress e.g. intercostal recessions, accessory muscle usage, tachypnoea
- Cyanosis
- Decreased level of consciousness
- Stridor may decrease due to worsening airway obstruction
- Decreased air entry on auscultation of the chest
- Tachycardia

# Differential Diagnosis
 

- **Epiglottitis**: Sudden onset high fever, drooling, and dysphagia are seen without the barking cough of croup. Usually secondary to Haemophilus influenzae B and so significantly rarer since routine immunisation against this.
- **Bacterial tracheitis**: Suspect if acute deterioration following initial viral symptoms, with high fevers, stridor and respiratory distress.
- **Foreign body aspiration**: No prodrome or fever, usually sudden onset of choking, cough or wheeze after eating or playing with small objects.
- **Anaphylaxis**: Rapid onset stridor, possible urticarial rash and facial swelling; suspect if history of previous episodes with allergens or family history of atopy.
 

#  Investigations
 
Diagnosis is clinical, and investigations need to be carefully considered as distressing the child may lead to worsening of symptoms due to agitation.

Further investigation may include: 

- Pulse oximetry should be done to determine if supplementary oxygen is required.
- Chest X-ray may be of use if a differential diagnosis such as an inhaled foreign body is suspected. 
       - In croup, an X-ray may show a steeple sign, where the upper trachea is seen to taper.
 

#  Management

Classifying the severity of croup is key to determining appropriate management:

| Severity                     | Description                                                                                                                                                                                                                                                                                       |
|------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Mild                         | Seal-like barking cough but no stridor or sternal/intercostal recession at rest.                                                                                                                                                                                                                  |
| Moderate                     | Seal-like barking cough with stridor and sternal recession at rest; no (or little) agitation or lethargy.                                                                                                                                                                                          |
| Severe                       | Seal-like barking cough with stridor and sternal/intercostal recession associated with agitation or lethargy.                                                                                                                                                                                     |
| Impending respiratory failure | Minimal barking cough, stridor may become harder to hear. Increasing upper airway obstruction, sternal/intercostal recession, asynchronous chest wall and abdominal movement, fatigue, pallor or cyanosis, decreased level of consciousness or tachycardia. The degree of chest wall recession may diminish with the onset of respiratory failure as the child tires. A respiratory rate of over 70 breaths/minute is also indicative of severe respiratory distress. |

Mild cases with no stridor or chest wall recessions at rest may be treated at home with a single dose of oral dexamethasone (0.15mg/kg). In children treated at home, families should be safety-netted on signs of deterioration and advised to check on the child regularly and encourage fluids. Paracetamol or ibuprofen can be used for fever and pain.

Children with any of the following should be considered for hospital admission:

* Stridor and/or sternal recession at rest
* High fever
* Respiratory rate > 60
* Cyanosis
* Lethargy or agitation
* Fluid intake < 75% of normal or no wet nappies for 12 hours
* Aged under 3 months
* Chronic conditions such as immunodeficiency, chronic lung disease or neuromuscular disorders

Management is supportive as there is no treatment indicated for the usual causative viruses, and may include:

- Supplementary oxygen if low saturations - consider how best to deliver this so as not to distress the child (e.g. a parent holding an oxygen mask to the face)
- Steroids for all - if unable to swallow oral dexamethasone or prednisolone can give nebulised budesonide
- Nebulised adrenaline for temporary symptom relief
- Anaesthetics +/- ENT input if concerns regarding airway or respiratory failure

# Complications

- Dehydration secondary to poor fluid intake during illness
- Pneumonia due to secondary bacterial infection 
- Respiratory failure 
- Death is very rare (1 in every 30,000 cases)

# Prognosis

Usually, symptoms resolve within 48 hours but may last longer. Occasionally, severe upper airway obstruction can occur, causing respiratory failure and arrest.

# NICE Guidelines

[NICE CKS: Croup](https://cks.nice.org.uk/topics/croup/)

#  References
 
[BNF Treatment summaries: Croup](https://bnf.nice.org.uk/treatment-summaries/croup/)

[Patient.info: Croup](https://patient.info/doctor/croup-pro)
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Paediatrics
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Croup
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Paediatrics
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Croup, characterised by stridor and a barking cough, is commonly caused by the parainfluenza virus in children aged 6 months to 3 years.
A 2-year-old boy presents to the paediatric emergency department (ED) after his parents noted that he was struggling with his breathing. They note that for the last three days, he has had a dry cough and runny nose with mild temperature spikes.

On examination, the boy is tachypnoeic and using his accessory muscles. His temperature is 38°C, and there is a high-pitched rasping sound audible during inspiration.

Given the likely diagnosis, which of the following is the most likely causative organism?
a