Croup and acute epiglottitis

Overview

Stridor is a harsh noise, mostly on breathing in, from narrowing of the larynx or trachea. In an acutely ill child the two classic causes are croup, a common, usually mild viral illness, and acute epiglottitis, a rare but life-threatening bacterial infection. Getting the distinction right decides whether you give steroids at the bedside or call the anaesthetist.

Croup (acute laryngotracheobronchitis)

Definition

Croup is respiratory distress with inspiratory stridor, a barking (brassy) cough and hoarseness, caused by obstruction of the larynx, trachea and sometimes the bronchi.

Epidemiology and aetiology

• Age 3 months to 5 years, peak in the second year.
• More common in boys and in winter; spread person to person; about 15% have a strong family history.
• Parainfluenza viruses (types 1, 2, 3) cause about 75%.
• Others: influenza A and B, adenovirus, RSV, measles.

Pathophysiology

Infection starts in the nasopharynx and spreads down to the larynx and trachea, causing redness, swelling and narrowing by fibrinous exudate (Akbar). In a child's small airway a slight loss of diameter from mucosal oedema raises resistance steeply; on breathing in, the subglottic walls are pulled inwards, which worsens the narrowing and produces stridor (Nelson). Gas exchange in the alveoli is usually normal.

Clinical features

• 1 to 2 days of cold, coryza and low-grade fever.
• Over 12 to 48 hours the cough becomes barking, with hoarse voice and inspiratory stridor.
• Symptoms are worse at night and with crying or agitation.
• Recession, raised respiratory rate, prolonged inspiration; cyanosis only if obstruction is severe.
• Child usually not toxic; illness lasts 3 to 7 days. Family members may have colds.

Warning signs (need admission)

• Stridor at rest (stridor only on crying is mild).
• Marked recession, agitation or reduced consciousness.
• Cyanosis, pallor, hypoxia.
• Progressive stridor, toxic appearance (think bacterial tracheitis or epiglottitis).

Investigations

• Diagnosis is clinical; treat distress before ordering tests.
• Neck X-ray: subglottic narrowing, the "steeple sign". Not needed in typical cases.
• White cell count is normal.
• Pulse oximetry and, in severe cases, blood gases.

Differential diagnosis

Management

• Keep the child calm on the parent's lap; disturb as little as possible.
• Cold humidified oxygen if hypoxic. Mist (steam from a vaporiser or cold mist from a nebuliser) may ease distress (Akbar).
• Dexamethasone 0.6 mg/kg as a single dose (oral or IM) (Akbar; Nelson 0.6-1 mg/kg): very effective and shortens the illness. Nelson notes it helps mild, moderate and severe croup, reducing admissions and hospital stay.
• Nebulised adrenaline for moderate to severe croup: racemic epinephrine 0.25 to 0.5 mL of 2.25% in 3 mL saline, repeatable as often as every 20 minutes (Akbar). The effect peaks in 10-30 minutes and fades within 60-90 minutes, so a child given it is observed for at least 2-3 hours for rebound (Nelson).
• Antibiotics only if secondary bacterial infection is suspected.
• Do not give sedatives, expectorants, bronchodilators or antihistamines.
• Airway support (intubation) if the child tires or obstruction becomes complete.

Complications and recurrence

• Viral pneumonia is the commonest complication (1-2%); secondary bacterial tracheitis or pneumonia (Nelson).
• Hypoxia and respiratory fatigue; respiratory failure.
• Croupy cough may be an early sign of asthma (Akbar).
• Stridor under 4 months of age or lasting over 1 week raises the chance of another lesion (such as subglottic stenosis, haemangioma, vascular ring) and calls for imaging and laryngoscopy (Nelson).

Acute epiglottitis (supraglottitis)

Epidemiology and pathogenesis

• Infection of the epiglottis, aryepiglottic folds and arytenoid tissues.
• Age 2 to 5 years; Akbar calls it rare under 2, but Nelson puts about a quarter of cases under 2 years; more in boys and in winter.
• Organism enters directly and the child becomes bacteraemic. The tissues are oedematous and packed with neutrophils and fibrin, so the swollen epiglottis can suddenly plug the airway.

Causative organisms

• Haemophilus influenzae type b (Hib) classically.
• Since Hib vaccination: Streptococcus pyogenes, Streptococcus pneumoniae, non-typeable H. influenzae, Staphylococcus aureus.

Clinical features

• Abrupt onset of high fever (39 to 40°C) over a few hours.
• Toxic, anxious, irritable child; muffled voice; sore throat and difficulty swallowing.
• Drooling because saliva cannot be swallowed.
• Stridor and moderate to severe distress.
• Sits upright, leaning forward, with the neck hyperextended and the mouth open (Nelson: tripod or sniffing position).
• Barking cough is rare; other family members are usually well.

Investigations

• Done only once the airway is safe, or by a team ready to intubate.
• Direct laryngoscopy in theatre or ICU: large, cherry-red, swollen epiglottis confirms it.
• Lateral neck X-ray (only if the child is stable and accompanied): swollen epiglottis, the "thumb sign".
• Leucocytosis with neutrophilia; blood culture and epiglottic swabs (taken at intubation).

Croup versus epiglottitis

Differential diagnosis of acute upper airway obstruction

Croup, epiglottitis, bacterial tracheitis, foreign body, retropharyngeal or peritonsillar abscess, diphtheria, angioedema or anaphylaxis, hypocalcaemic laryngospasm, and in infants congenital causes such as laryngomalacia (commonest cause of stridor in infants: low-pitched, worse on crying and lying on the back, better prone; usually outgrown).

Airway intervention and management

1. Emergency: call senior anaesthetic and ENT help; keep the child with the parent in the position of comfort.
2. Oxygen by mask if tolerated.
3. Secure the airway under controlled conditions (theatre or ICU): nasotracheal intubation is preferred; a surgeon ready to perform tracheostomy if needed. Breathing support continues until the swelling settles (Akbar: after several days; Nelson: most children can be extubated within 48-72 hours).
4. Take blood culture and swabs after the airway is secured.
5. IV antibiotics for 7 to 10 days: ceftriaxone 100 mg/kg/day, cefotaxime or meropenem; chloramphenicol 50 to 75 mg/kg/day as an alternative.
6. Fluids and electrolytes; intensive monitoring.
7. Extubate once the swelling has gone (usually within a few days); complete about 10 days of antibiotics.

Prophylaxis for contacts (Hib)

Rifampicin 20 mg/kg orally once daily for 4 days (maximum 600 mg) for all household members when the household includes:

• a child under 4 years who is not fully immunised;
• an infant under 12 months who has not finished the primary series;
• an immunocompromised person.

Hib vaccination in the routine schedule has made epiglottitis much rarer.

Complications

• Complete airway obstruction and death unless treated promptly.
• Bacteraemia: Hib also causes meningitis, pneumonia, septic arthritis and cellulitis (Akbar), so look for other foci.

Quick revision

• Croup: parainfluenza, 3 months to 5 years, gradual, barking cough, hoarse, stridor, worse at night.
• Steeple sign; normal white count; hypoxia late.
• Dexamethasone 0.6 mg/kg once; nebulised adrenaline for moderate to severe (short action).
• No sedatives, expectorants, bronchodilators or antihistamines.
• Epiglottitis: Hib, 2 to 5 years, abrupt high fever, toxic, drool, muffled voice, sits forward.
• Thumb sign; cherry-red epiglottis at laryngoscopy.
• Do not examine throat; nasotracheal intubation; IV ceftriaxone 7 to 10 days.
• Rifampicin 20 mg/kg daily for 4 days for household contacts at risk.

Written by The House Job from standard references (Basis of Paediatrics by Pervez Akbar; Nelson Essentials of Paediatrics).

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