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
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).
HISTORY
- 2 to 3 days of nonspecific prodromal syndrome with low-grade fever, coryza, and rhinorrhea
- Onset and recurrence at night when child is sleeping
- Symptoms often resolve en route to the hospital, as the child is exposed to cool night air.
- Lack of prodrome indicates spasmodic croup.
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
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
- 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
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 ⅓; 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.
COMPLICATIONS
- Rare
- Subglottic stenosis in intubated patients
- Bacterial tracheitis
- Cardiopulmonary arrest
- Pneumonia
REFERENCES
11 Tibballs �J, Watson �T. Symptoms and signs differentiating croup and epiglottitis. J Paediatr Child Health. 2011;47(3):77-82.22 Bjornson �C, Russell �KF, Vandermeer �B, et al. Nebulized epinephrine for croup in children. Cochrane Database Syst Rev. 2013;10:CD006619.33 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):309-314.44 Dobrovoljac �M, 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):79-85.55 Cetinkaya �F, T �fek �i �BS, Kutluk �G. A comparison of nebulized budesonide, and intramuscular, and oral dexamethasone for treatment of croup. Int J Pediatr Otorhinolaryngol. 2004;68(4):453-456.66 Russell �KF, Liang �Y, O'Gorman �K, et al. Glucocorticoids for croup. Cochrane Database Syst Rev. 2011;(1):CD001955.77 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):1014-1021.88 Moraa �I, Sturman �N, McGuire �T, et al. Heliox for croup in children. Cochrane Database Syst Rev. 2013;(12):CD006822.99 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
- 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
Bronchiolitis; Epiglottitis; Tracheitis, Bacterial �
CODES
ICD10
- J05.0 Acute obstructive laryngitis [croup]
- J20.9 Acute bronchitis, unspecified
- J38.5 Laryngeal spasm
- J04.2 Acute laryngotracheitis
ICD9
- 464.4 Croup
- 466.0 Acute bronchitis
- 478.75 Laryngeal spasm
- 464.20 Acute laryngotracheitis without mention of obstruction
SNOMED
- 71186008 Croup (disorder)
- 85915003 Laryngotracheobronchitis
- 406444002 Laryngeal spasm (disorder)
- 55130001 Laryngotracheitis (disorder)
CLINICAL PEARLS
- 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).