Croup (Laryngotracheobronchitis)

Croup is viral laryngotracheobronchitis. The larynx, trachea and bronchi swell, and that swelling gives you the barking cough, inspiratory stridor and hoarseness. Parainfluenza virus is the cause most often identified.

Croup hits about 3% of children aged 6 months to 3 years. It accounts for about 7% of hospitalizations for fever or acute respiratory illness in children under 5. Most children with croup never get admitted. Fewer than 5% are, and 1% to 3% of those admitted need intubation.

Why Kids Are Different

• Small lumen: In a small airway, the same swelling takes away far more. Laminar resistance rises with the fourth power of the radius (Poiseuille). Flow through the narrowed segment speeds up and turns turbulent, and that turbulence produces stridor.
• Night-time pattern: Nights are often the worst. Symptoms peak within 24 to 48 hours. Most episodes resolve within 48 hours to a week.
• Fever is optional: Many children run a low-grade fever. No fever does not lower your suspicion of croup.
• Look-alikes are serious: Epiglottitis (now rare where Hib is vaccinated) and bacterial tracheitis both show up with stridor, and both can deteriorate fast. Use the Differential Diagnosis table.

Every child with stridor gets the Westley Croup Score. Add up the five signs, then rescore after each treatment. The total grades severity at the bedside, but read it alongside color, work of breathing and mental status. Never let the number stand alone.

Westley Croup Score

Age-Specific Presentation

• Infants under 6 months: Croup is less typical this young. Stridor that worsens with crying points to other causes, such as an airway hemangioma.
• Toddlers and preschoolers (6 months to 3 years): This is the classic age. Expect a barking cough, hoarseness and stridor, with no drooling and no toxic look.
• Children over 3 years: Past 3 years, croup falls outside the AFP age range. Epiglottitis (3 to 12 years) and bacterial tracheitis (under 6 years) have to be ruled out.

Croup is diagnosed at the bedside. Routine imaging and labs are not needed. Save radiography for the child in whom another diagnosis is suspected.

In one intensive care series, drooling was highly sensitive and specific for epiglottitis. Cough is what sets croup apart. The steeple sign on the neck radiograph is neither specific nor sensitive for croup.

Every child with croup gets dexamethasone, whatever the severity. Moderate or severe croup adds nebulized epinephrine. Agitation makes the airway worse, so keep the child calm, comfortable and with a caregiver.

Mild (Westley 2 or less)

• Dexamethasone once, by mouth if the child can swallow (see Medications & Dosing).
• Oxygen for hypoxemia or severe respiratory distress.
• Rescore after treatment. Discharge or transport follows local protocol and medical direction.

Moderate or Severe (Westley 3 or more)

• Dexamethasone as above.
• Nebulized epinephrine, racemic 2.25% or L-epinephrine 1 mg/mL, per protocol, for stridor at rest or respiratory distress. Epinephrine is recommended for moderate to severe croup. Rescore 10 to 30 minutes later. In the 1978 racemic trial, scores improved at 10 and 30 minutes but not at 120 minutes.
• Observe at least 2 hours after the last epinephrine dose before any discharge.
• Transport and escalate if stridor at rest, retractions or cyanosis persist, the score does not fall, or the child needs repeated epinephrine. Thresholds are protocol-dependent.

Treatments That Do Not Help

• Humidified mist: Mist does not meaningfully help moderate croup. Do not use it as treatment.
• Heliox: The evidence is thin. A 2021 Cochrane review found benefit that is uncertain. Use it only where protocol and medical direction allow.
• Outdoor cold air: One single-center randomized trial found that 30 minutes of outdoor air below 10 °C, added to oral dexamethasone, improved the Westley score at 30 minutes more often than room air did (49% vs 24%). Think of it as an adjunct. It never replaces steroid or epinephrine.

Bacterial tracheitis and epiglottitis are the ones to suspect. Think of them when the child looks toxic, runs a high fever, drools, has a muffled voice, sits in a sniffing position, or fails to respond to croup treatment.

1. Protect the airway first: keep the child with the caregiver, sitting upright. Do not examine the throat or lay the child flat unless the airway team is ready to intubate.
2. Intubate for severe airway obstruction: tracheal intubation, supportive therapy and broad-spectrum antibiotics are appropriate in severe airway infection and obstruction (Paramedic/RN/CCT, per local protocol).
3. Antibiotics: Staphylococcus aureus leads in published series. Methicillin-sensitive strains dominated one 2019 case series (see References). Ceftriaxone on its own leaves MRSA uncovered, so empiric regimens add an agent active against S. aureus, MRSA included (for example vancomycin), chosen per local antibiogram, pediatric infectious disease input and protocol. Ceftriaxone dosing is in the table below.
4. Steroids: No evidence shows glucocorticoids change the outcome in bacterial tracheitis. Don't expect dexamethasone to treat these conditions.

Treat all three epinephrine rows as high-alert. Doses vary by protocol; follow local protocols and medical direction.

• Discharge: Send the child home only when the score is low, the child is comfortable after the observation period, and caregivers can recognize warning signs. Follow local protocol.
• Admission or transfer: Admit or transfer for persistent severe signs, a need for repeated epinephrine, or any airway concern. Thresholds are protocol-dependent.

Infants Under 6 Months

• Croup is less typical this young. Stridor that worsens with crying points to another cause, such as a laryngeal or airway hemangioma.
• Epiglottitis and bacterial tracheitis stay on the list. Age does not rule them out.

Recurrent Croup

• More than two episodes a year calls for evaluation. Clinically significant bronchoscopy findings were linked to prior intubation, age under 3 years and prematurity.

Children With Heart Disease or Frequent Treatment

• Nebulized epinephrine can push the heart rate up and cause other cardiac effects. Repeated treatments mean repeated monitoring.

Adolescents

• Past the AFP age range, croup is uncommon. Rule out epiglottitis and the other causes of stridor.
• Weight-based doses stop at the stated maximum. For adult dosing, use protocol thresholds.

Roles are usually set per state or agency protocol.

• Keep the child with a caregiver: Crying makes the airway worse, so have the caregiver hold the child upright and do not separate them.
• Handoff: give a structured handoff (MIST or IMIST-AMBO) with the Westley score before and after each treatment and the time of every dose.
• Cold air: Where protocol allows, a short outdoor cold-air exposure may add to the steroid. It never stands in for dexamethasone or epinephrine.