Croup - Laryngotracheobronchitis

Viral Laryngotracheobronchitis (Croup) is the most common cause of stridor commonly affecting children between 6 months to 6 years old, with a peak in the fall and early winter months. Croup is acquired through inhalation of the virus. 

Possible agents could be parainfluenza virus (most common), rhinovirus. enterovirus, respiratory syncytial virus, influenza virus and human metapneumovirus.

Clinical Presentation 
Typically, symptoms begin after 1 to 3 days of URTI symptoms (nasal congestion, rhinorrhea, cough, and low-grade fever). Classic symptoms include a harsh barking cough, hoarse voice, and stridor. Symptoms often tend to be worse at night and the severity of symptoms is related to the amount of edema and inflammation of the airway. 

Diagnosis and Assessment of Severity 
Look for tachypnea, stridor at rest, nasal flaring, retractions, lethargy or agitation, and oxygen desaturation. Symptoms are most severe on 3rd or 4th day of illness. Agitation and crying increase oxygen demand and may worsen airway compromise. Bloods and imaging are only required in children who fail to respond to conventional therapy. X Rays may demonstrate “steeple sign” (subglottic narrowing). 

Steeple Sign

Croup is a clinical diagnosis

Steeple sign may be present in normal children and can be absent in up to half of those with croup

Management 
Treatment is directed at decreasing airway obstruction and keeping the child comfortable 

• Corticosteroids: All patients with croup get steroids as a one- time dose (PO/IM/IV). Steroids reduce the severity and duration of symptoms and result in a decrease in return visits and hospital length of stay. The long half-life of dexamethasone (36-54 h) often allows for a single injection. Studies have shown that dexamethasone dosed at 0.15 mg/kg is as effective as 0.3 mg/kg or 0.6 mg/kg (with a maximum daily dose of 10 mg). Effects can be seen within 1 hour of oral administration. Nebulized budesonide 2 mg as a single dose and IM dexamethasone (0.6mg/kg) are alternatives to PO dexamethasone in children who are vomiting.

Treatment of croup: Nebulized epinephrine for moderate to severe croup and corticosteroids for all

• Epinephrine: Epinephrine comes as two different forms: racemic, which is composed of equal parts of L- and D-isomers, and L-epinephrine, which is the drug routinely used in acute situations in concentrations of 1:1000 and 1:10,000. 
• L-Epinephrine (1:1000): 0.5 ml/kg neb or 5ml maximum  
• Racemic Epinephrine (2.25%): 0.05ml/kg neb or max 0.5ml

Mild croup generally does not require epinephrine. For those with moderate or severe croup who receive nebulized epinephrine, observe in the ED for at least 3 hours before considering discharge. Epinephrine decreases airway edema through vasoconstrictive alpha effects and acts wishing 10-min lasting up to 2 hours. The use of Adrenaline decreases the number of children with croup requiring intubation, ITU admissions, and admission to the hospital. 

Observation for about 3 hours is recommended because an increase in croup scores can occur between doses of epinephrine nebulisation

• Intubation is reserved for cases of severe croup not responding to medical treatment. When intubation is necessary, use endotracheal tubes smaller than recommended for patient size and age to avoid traumatizing the inflamed mucosa. 

Treatment options with limited evidence: 

• Cool Mist: Humidified air was used to treat croup, but they are no longer recommended as studies have consistently failed to show clinical improvement with these interventions.
• Heliox (70% helium/30% oxygen): Despite its theoretical benefits, studies show no definitive advantage of heliox over conventional treatment.24-28
• Beta 2 Agonists: Insufficient data. Concerns about risk of worsening upper airway obstruction as β-receptors on the vasculature cause vasodilation (as compared to the vasoconstrictive α effects of epinephrine), which might worsen upper airway edema in croup, and there is no smooth muscle in the upper airway. Therefore, β-agonists are not recommended for treatment of croup.
• Antibiotics have no role in uncomplicated croup 
• Antitussives have no proven effect on the course or severity of croup and may increase sedation

Differential Diagnosis (Consider if no relief with Rx)

• Bacterial tracheitis
• Laryngomalacia
• Tracheomalacia
• Vascular rings
• Epiglottitis (unlikely if vaccinated)
• Foreign body aspiration
• Peritonsillar abscess
• Retropharyngeal abscess
• Tracheo-esophageal fistula

Admit 

• Moderate to Severe Croup
• Looking toxic and not tolerating oral fluids
• Comorbidities 
• Social Issues
• Persistent stridor at rest, tachypnea, retractions, and hypoxia

Discharge Advice 

• Advise the parents/carers to use either paracetamol or ibuprofen to treat a child who is distressed due to fever. 
• Encourage the child to take fluids regularly.
• To check on the child regularly, including through the night.

References and Further Reading :

1. https://cks.nice.org.uk/croup#!scenario
2. http://www.ebmedicine.net/topics.php?paction=showTopic&topic_id=334
3. Russell KF, Liang Y, O’Gorman K, Johnson DW, Klassen TP. Glucocorticoids for croup. Cochrane Database of Systematic Reviews 2011, Issue 1. Art. No.: CD001955.
4. Johnson DW. Croup. BMJ Clin Evid. 2009; 2009: 0321.
5. Bjornson, C.L. and and Johnson, D.W. (2013)  Croup in children. CMAJ. 185(15), 1317-1323
   
   

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        Lakshay Chanana

        

        Speciality Doctor

        Northwick Park Hospital

        Department of Emergency Medicine

        England

   
   

        @EMDidactic