Croup

Introduction

• Acute clinical syndrome of:
  • Hoarse voice
  • Seal bark cough
  • Inspiratory stridor
• Usually viral infection causing laryngotracheobronchitis
• Peak incidence age 1-2 years 60/1000
• Peaks in winter months due to epidemics of Parainfluenza 1, 2, influenza A, adenovirus, RSV, enterovirus and possibly Mycoplasma pneumoniae
• Some viral exanthems e.g. varicella, can cause croup also
• Peaks at night and on day 2-3 of illness
• Tends to be more severe in younger children due to smaller airways, loose submucosal tissues and tight cricoid cartilage (narrowest part of airway in <8yo)
• May also have wheeze due to bronchitis

History

• Typically recent viral URTI with subsequent seal-bark cough, hoarse voice and stridor
• Stridor may only be apparent when distressed
• Initially inspiratory stridor indicating obstruction at laryngeal level or higher
• Expiratory or biphasic stridor indicates more severe laryngeal obstruction or below the larynx
• Stridor peaks at 24-48 hours and resolves over days without treatment
• Important factors
  • Feeding issues, apnoea, cyanotic attacks or swallowing difficulties
• Stridor in between episodes of croup
  • Important as congenital airway disorder makes severe obstruction more likely
• Vaccination history
  • Hib and Diphtheria are rare causes of airway obstruction in children

Spasmodic/recurrent croup

• Older children may present with recurrent or spasmodic croup of sudden onset with no viral prodrome
• Thought to be allergic in origin
• Typically atopic individuals
• Should be treated the same as viral croup

Risk factors for severe croup

• Congenital airway narrowing
  • Down syndrome
  • Subglottic stenosis
• Previous admissions with severe croup
• Uncommon <6mo, rare <3mo: Consider alternative diagnosis

Severity

Examination

• Minimise distress to child at all times. Do not examine throat. 
• Nasal discharge
• URTI signs
• Mild fever but no signs of toxicity
• May have wheeze
• Hyperextension or other abnormal positioning of neck may suggest epiglottitis or retropharyngeal abscess
• Any neck tenderness or drooling should be taken very seriously

Investigations

• In stable cases, where diagnosis may be unclear, a lateral neck soft tissue X-ray can help differentiate from epiglottitis or retropharyngeal abscess
• CXR, NPA, Floqswab are usually not required and may only worsen the childs distress

CXR in croup

• Steeple sign/wine bottle sign
  • AP uniform narrowing of subglottic airway
• Distension of hypopharynx due to attempts at reducing airway resistance
• Normal epiglottis and narrowing of subglottic region

Differential diagnosis

• Foreign body
• Epiglottitis
• Diphtheria
• Bacterial tracheitis
• Tonsillitis
• Congenital airway malformation e.g. laryngotracheomalacia, subglottic stenosis, cord paresis
• Retropharyngeal abscess
• Allergic oedema
• Airway trauma

Treatment

• Mild/moderate croup
  • All children should be treated with steroids unless only cough (RCH)
    • Reduces relapse rate, length of stay, ICU admissions and intubation rate
  • Oral dexamethasone 0.15mg/kg stat or prednisolone 1mg/kg repeated at 24 hours 
  • No benefit in adding inhaled corticosteroids
  • No place for antibiotics
  • No benefit of steam inhalation
  • No benefit of heliox or humidified air or antitussives
  • If mild, can be discharged 30 minutes after steroid dose (assuming safe social situation and no concern for congenital airway issues)
  • If moderate (i.e. stridor at rest), treat and monitor for improvement to no stridor at rest and at least 30 minutes prior to discharge
• Severe croup
  • Nebulised adrenaline 5mL of 1:1000 nebulised with O2 for all children
    • To buy time while steroids take effect
    • Does not reduce stay in hospital or intubation rates
    • Can repeat at 10 minutes if required
    • If improves to no stridor at rest after 4 hours monitoring, can still be sent home
    • If improves, then deteriorates, repeat adrenaline dose and consider admission/transfer
  • AND 0.6mg/kg IV/IM dexamethasone
  • Intubation may be required. Ideally in theatre or paediatric ICU with gaseous induction and ETT 1.0mm smaller than predicted size

Prognosis

• Steroids make no difference to duration of underlying viral aetiology
• Most cases will settle with time, usually in days but sometimes weeks
• Anecdotal evidence suggests repeat offenders may benefit from oral steroids at home at the first sign of a bout of croup

Last Updated on October 27, 2021 by Andrew Crofton