> Table of Contents > Croup (Laryngotracheobronchitis)
Croup (Laryngotracheobronchitis)
Garreth C. Debiegun, MD, FACEP, FAWM
image BASICS
DESCRIPTION
  • Croup is a subacute viral illness characterized by upper airway symptoms such as barking cough, stridor, and fever. “Croup” is used to refer to viral laryngotracheitis or laryngotracheobronchitis (LTB), although it is sometimes used for LTB with pneumonitis, bacterial tracheitis, or spasmodic croup.
  • Most common cause of upper airway obstruction or stridor in children
  • Spasmodic croup: noninfectious form with sudden resolution
    • No fever or radiographic changes
    • Initially treated as croup
    • Usually self-limiting and resolves with mist therapy at home
    • Often recurs on same night or in 2 to 3 nights
  • System(s) affected: pulmonary, respiratory
  • Synonym(s): infectious croup; viral croup
EPIDEMIOLOGY
  • Predominant age
    • Common among children 7 months to 3 years
    • Most common during the 2nd year of life
    • Rare among those >6 years
  • Predominant sex: male > female (1.5:1)
  • Timing
    • Possible during any time of year but is most common in autumn and winter (with parainfluenza 1 and respiratory syncytial virus [RSV])
Incidence
  • Six cases per year per 100 children <6 years old
  • 1.5-6% of cases require hospitalization.
  • 2-6% of those require intubation.
  • Decreasing incidence in the United States and Canada
ETIOLOGY AND PATHOPHYSIOLOGY
  • Subglottic region/larynx is entirely encircled by the cricoid cartilage.
  • Inflammatory edema and subglottic mucus production decrease airway radius.
  • Small children have small airways with more compliant walls.
  • Negative-pressure inspiration pulls airway walls closer together.
  • Small decrease in airway radius causes significant increase in resistance (Poiseuille law: resistance proportional to 1/radius4).
  • Usually viruses that initially infect oropharyngeal mucosa and then migrate inferiorly
  • Parainfluenza virus
    • Most common pathogen: 75% of cases
    • Type 1 is the most common, causing 18% of all cases of croup.
    • Types 2, 3, and 4 are also common.
    • Type 3 may cause a particularly severe illness.
  • Other viruses: RSV, paramyxovirus, influenza virus type A or B, adenovirus, rhinovirus, enteroviruses (coxsackie and echo), reovirus, measles virus where vaccination not common, and metapneumovirus
  • Haemophilus influenzae type B now rare with routine immunization
  • May have bacterial cause: Mycoplasma pneumoniae has been reported.
RISK FACTORS
  • History of croup
  • Recurrent upper respiratory infections
  • Atopic disease increases the risk of spasmodic croup.
COMMONLY ASSOCIATED CONDITIONS
  • If recurrent (>2 episodes in a year) or during first 90 days of life, consider host factors.
  • Underlying anatomic abnormality (e.g., subglottic stenosis)
    • In one study, found to be present in 59% children with recurrent croup
  • Paradoxical vocal cord dysfunction
  • Gastroesophageal reflux disease
  • Neonatal intubation
image DIAGNOSIS
  • Most children who present with acute onset of barky cough, stridor, and chest wall indrawing have croup.
  • Croup is a clinical diagnosis; lab tests and imaging serve only ancillary purposes.
  • Classic “seal-like” barking, spasmodic cough
  • May have biphasic stridor
  • Low- to moderate-grade fever
  • Upper respiratory infection prodrome lasting 1 to 7 days
  • Severity usually is determined by clinical observation for signs of respiratory effort: nasal flaring, retractions, tripoding, sniffing position, abdominal breathing, and tachypnea. Later symptoms: hypoxia/cyanosis or fatigue
  • Westley croup score (≤2 mild; 3 to 7 moderate; ≥8 severe), most useful for research purposes
    • Level of consciousness: normal, including sleep, 0; disoriented, 5
    • Cyanosis: none, 0; with agitation, 4; at rest, 5
    • Stridor: none, 0; with agitation, 1; at rest, 2
    • Air entry: normal, 0; decreased, 1; markedly decreased, 2
    • Retractions: none, 0; mild, 1; moderate, 2; severe, 2
  • No change in stridor with positioning
  • Nontender larynx
  • Inflamed subglottic region with normal-appearing supraglottic region
  • Differentiate from epiglottitis: non-toxic-appearing, normal voice, no drooling, is coughing (1).
PHYSICAL EXAM
  • Pulse oximetry often is normal because there is no disturbance of alveolar gas exchange.
  • Overall appearance: Is the child comfortable or struggling?
  • Work of breathing: labored or comfortable?
  • Sound of breathing and voice: hoarse, stridor, inspiratory wheezing, short sentences?
  • Observed/subjective tidal volume: sufficient for child's size?
DIFFERENTIAL DIAGNOSIS
  • Epiglottitis: currently rare
  • Foreign body aspiration
  • Subglottic stenosis (congenital or acquired)
  • Bacterial tracheitis
  • Simple upper respiratory infection
  • Retropharyngeal or peritonsillar abscess
  • Trauma
  • Allergic reaction (acute angioneurotic edema)
  • Airway anomalies (e.g., tracheo-/laryngomalacia)
  • Other anatomic obstructions: subglottic hemangioma, subglottic cyst
DIAGNOSTIC TESTS & INTERPRETATION
  • No laboratory abnormality is diagnostic.
  • WBCs may be low, normal, or elevated.
  • Lymphocytosis is expected but not required.
  • Rapid antigen or viral culture tests are available in some centers.
    • Guide isolation precautions, not management.
Initial Tests (lab, imaging)
  • Posteroanterior and lateral neck films show funnel-shaped subglottic region with normal epiglottis: “steeple,” “hourglass,” or “pencil point” sign (present in 40-60% of children with LTB).
  • CT may be more sensitive for defining obstruction in a confusing clinical picture.
  • Patient should be monitored during imaging; airway obstruction may occur rapidly.
Test Interpretation
  • Inflammatory reaction of respiratory mucosa
  • Loss of epithelial cells
  • Thick mucoid secretions
image TREATMENT
GENERAL MEASURES
  • Minimize lab tests, imaging, and procedures that upset the child; agitation worsens tachypnea and can be more detrimental than accepting a clinical diagnosis.
  • ECG monitoring and pulse oximetry
    • Frequent checks are more sensitive to worsening disease than is pulse oximetry.
MEDICATION
First Line
  • Well established in the literature; cornerstones of treatment are immediate nebulized epinephrine and dexamethasone.
  • Racemic or L-epinephrine (Equal efficacy and side effect profiles; L-epinephrine is used for most other hospital purposes and is less expensive.) (2)[A]
    • Reserved for more severe cases with stridor at rest
    • Racemic epinephrine: 0.05 mL/kg/dose (max 0.5 mL) of 2.25% solution nebulized in normal saline to total volume of 3 mL
    • L-epinephrine: 0.5 mL/kg/dose (max 5 mL) of a 1:1,000 dilution nebulized
    • P.243

    • Onset in 1 to 5 minutes, duration of 2 hours
    • Repeat as necessary if side effects are tolerated.
    • Observe child for 2 hours to ensure no recurrence after epinephrine wears off.
  • Corticosteroids
    • Dexamethasone (least expensive, easiest), 0.15-0.6 mg/kg; higher doses have been traditional care, but studies have shown 0.15 mg/kg has equal efficacy (3)[B]. Single dose; IV/IM/PO has proven equal efficacy.
    • Randomized controlled trials show this begins to improve symptoms within 30 minutes (4)[A]; full effect by 4 hours
    • Other steroids (betamethasone, budesonide (5)[A], prednisolone) are beneficial; there may be minimal superiority of dexamethasone; also, dexamethasone carries benefit of single-dose administration (6,7)[A].
  • Heliox: a helium-oxygen mixture
    • Smaller, lower mass helium molecule (compared with nitrogen) theoretically maintains laminar flow in narrower airways and serves as bridge therapy to steroids.
    • Minimum of 60% helium must be used; 70% is preferable; 79% if patient has no oxygen requirement.
    • Limited data; a Cochrane review found no benefit in mild cases but likely benefit in moderate to severe croup as a bridge to steroid effect (8)[A].
  • Antibiotics are not indicated in this viral illness.
    • Antecedent or subsequent bacterial infection is possible but uncommon.
  • Oxygen as needed
  • Humidified air shows no clinical benefit.
Second Line
Oseltamivir for influenza A
SURGERY
  • Intubation rarely is required; tube 0.5 to 1 mm smaller than normal.
    • After trial of medical management, intubation is for fatigue caused by work of breathing or beginning total obstruction; not secondary to low oxygen saturation
    • Extubate in 3 to 5 days when there is an appropriate air leak around the endotracheal tube.
  • Tracheotomy: rarely; maintenance 3 to 7 days
COMPLEMENTARY & ALTERNATIVE MEDICINE
  • Although proven no benefit in hospital, may be helpful at home. Do not use high-temperature misters (e.g., teakettles) because of a risk of burns. A hot shower running in a bathroom is a good steam generator.
  • Some children respond well to cold, dry air.
  • Probiotics may decrease the incidence of upper respiratory tract infections (9)[A].
INPATIENT CONSIDERATIONS
Admission Criteria/Initial Stabilization
  • Minor cases need no visit to a hospital or primary care physician (PCP).
  • Outpatient care in mild cases
  • Admit patients who do not respond to therapy or have recurrent stridor at rest after epinephrine wears off. Also admit those who have oxygen requirement, pneumonia, or congestive heart failure.
  • In most cases, observation in the ED after medical management is sufficient.
Discharge Criteria
  • >2 hours since last epinephrine
  • No stridor at rest, no difficulty breathing
  • Child able to tolerate liquids PO
  • No underlying medical condition
  • Caretakers able to assess changes to clinical picture and reaccess medical care
image ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Patient Monitoring
Most patients will be seen in an ED or PCP office setting.
DIET
  • NPO and IV fluids for severe cases
  • Frequent small feedings with increased fluids for mild cases
PATIENT EDUCATION
  • Must keep the patient quiet; crying may exacerbate symptoms.
  • Educate parents about when to seek emergency care if mild cases progress.
  • Provide emotional support and reassurance for the patient.
PROGNOSIS
  • Up to 1/3 of patients will have a recurrence.
  • Recovery is usually full and without lasting effects.
  • If multiple recurrences, consider referral to ENT specialist to evaluate for possible anatomic etiology.
REFERENCES
1. Tibballs J, Watson T. Symptoms and signs differentiating croup and epiglottitis. J Paediatr Child Health. 2011;47(3):77-82.
2. Bjornson C, Russell KF, Vandermeer B, et al. Nebulized epinephrine for croup in children. Cochrane Database Syst Rev. 2013;10:CD006619.
3. Dobrovoljac M, Geelhoed GC. 27 years of croup: an update highlighting the effectiveness of 0.15 mg/kg of dexamethasone. Emerg Med Australas. 2009;21(4):309-314.
4. Dobrovoljac, Geelhoed GC. How fast does oral dexamethasone work in mild to moderately severe croup? A randomized double-blinded clinical trial. Emerg Med Australas. 2012;24(1):79-85.
5. Cetinkaya F, Tüfekçi BS, Kutluk G. A comparison of nebulized budesonide, and intramuscular, and oral dexamethasone for treatment of croup. Int J Pediatr Otorhinolaryngol. 2004;68(4):453-456.
6. Russell KF, Liang Y, O'Gorman K, et al. Glucocorticoids for croup. Cochrane Database Syst Rev. 2011;(1):CD001955.
7. Garbutt JM, Conlon B, Sterkel R, et al. The comparative effectiveness of prednisolone and dexamethasone for children with croup: a community-based randomized trial. Clin Pediatr (Phila). 2013;52(11):1014-1021.
8. Moraa I, Sturman N, McGuire T, et al. Heliox for croup in children. Cochrane Database Syst Rev. 2013;(12):CD006822.
9. Hao Q, Lu Z, Dong BR, et al. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database Syst Rev. 2011;(9):CD006895.
Additional Reading
&NA;
  • Bjornson CL, Johnson DW. Croup. Lancet. 2008;371(9609):329-339.
  • Cherry JD. Clinical practice. Croup. N Engl J Med. 2008;358(4):384-391.
See Also
&NA;
Bronchiolitis; Epiglottitis; Tracheitis, Bacterial
Codes
&NA;
ICD10
  • J05.0 Acute obstructive laryngitis [croup]
  • J20.9 Acute bronchitis, unspecified
  • J38.5 Laryngeal spasm
Clinical Pearls
&NA;
  • Parainfluenza virus is the most common pathogen but caused by many viruses.
  • Nebulized epinephrine only for stridor at rest
  • Dexamethasone 0.6 mg/kg PO × 1
  • Lateral neck films show funnel-shaped subglottic region with normal epiglottis: “steeple,” “hourglass,” or “pencil point” sign (present in 40-60% of children with LTB).