Topic Editor: Robert Giles, MBBS, BPharm
Review Date: 12/12/2012
Definition
Croup (acute laryngotracheobronchitis) is a common childhood respiratory illness. Inflammation and narrowing of the subglottic region of the larynx leads to partial upper airway obstruction. Croup symptoms include a barking cough, hoarseness, stridor, and respiratory distress.
Description
- Croup occurs most commonly in children aged 6 months to 3 years
- Croup is generally due to an acute viral upper respiratory infection which causes inflammation, hyperemia and edema of the larynx. The most common causative viruses are Parainfluenza virus, human Coronavirus, Influenza A virus, human Bocavirus, Adenovirus, and Respiratory Syncytial Virus
- Partial obstruction of the subglottic airway causes the characteristic seal-like barking cough, stridor and increased work of breathing
- Obstructive symptoms usually resolve within 48 hours, although symptoms may persist for 5-6 days
- Patients may or may not present with manifestations of an acute viral upper respiratory tract infection
- Croup includes variants including spasmodic croup (recurrent), laryngotracheitis , laryngotracheobronchitis, and laryngotracheobronchopneumonitis
- Treatment is primarily with corticosteroids. The addition of nebulized epinephrine for symptom control is determined by the severity of the presentation
- Critical cases, with severe stridor, altered mentation, and impending respiratory failure can require intubation and ventilation
Epidemiology
Incidence/Prevalence
- Up to 15% of the pediatric ED visits in the U.S. are attributable to croup
- Annual incidence of croup is 1.5-6/100 children <6 years of age
- 13% of all children will experience at least one episode of croup
- 5% of children experience recurrent attacks of croup (at least 3 episodes)
Age- Croup occurs most commonly in children between 6 months and 3 years of age, peaking during the second year of life. It may also occur in older children and adolescents, and very rarely in adults
Gender
- Occurs more commonly in boys than in girls (3:2)
Risk factors
- Age <3 year
- Airway hyperreactivity
- Atopic disease increases risk of recurrent croup
- Family history of croup
- Personal history of croup
- Preexisting airway edema
- Previous intubation
- Season (most common in fall and winter)
- Anatomical anomalies (e.g. subglottic stenosis, Down's syndrome)
Etiology
- Viruses are identified in up to 80% of patients; though rarely, Mycoplasma pneumoniae or Corynebacterium diphtheria have also been isolated
- Parainfluenza virus serotype 1 is the most common causative agent in croup
- Other causative viruses include human Coronavirus, Influenza A, human Bocavirus, Adenovirus, Respiratory Syncytial Virus, Parainfluenza viruses of serotypes 2 and 3, Influenza B, echovirus, enterovirus, measles, mumps, and rhinovirus
- Spasmodic croup often presents without a concomitant viral infection and may have an allergic component
History
- Patients with croup typically present with an upper respiratory tract infection. Patients usually have a history of fever, cough and coryza. 12 to 72 hours later they develop characteristic features such as barking cough, dyspnea, hoarseness, stridor and wheezing
- Symptoms are often noted suddenly and are usually worse at night, and improve during the day, with peak symptoms generally being overnight between 24 and 48 hours of onset of symptoms. Children are often agitated and prefer sitting or being held upright
- It is common, if the history is sought, that the night prior to hospital presentation, the child had mild croup symptoms that resolved during the day then recurred with higher severity the day of presentation for medical care
- Croup generally self resolves within a week
Physical findings on examination
- Key findings in patients with croup:
- Agitation is common
- Chest wall retraction
- Cyanosis (severe croup)
- Decreased air movement
- Dyspnea
- Hoarseness of voice
- Increased work of breathing:
- Intercostal / subcostal recession
- Nasal flaring
- Tracheal tug
- Low-grade fever
- Normal or mildly inflamed pharynx
- Mental status change/obtunded (severe croup)
- Seal-like barking cough
- Stridor (Inspiratory, expiratory or biphasic)
- Tachycardia
- Tachypnea
- Wheeze
- History and examination should be sufficient to make a diagnosis of croup, but examination must be directed at assessing the severity of croup and excluding more sinister differential diagnoses
- Findings such as toxic appearance, drooling, loss of voice or difficulty in swallowing should raise concerns that the child may have a serious bacterial infection such as epiglottitis, bacterial tracheitis or retropharyngeal abscess
- Children with respiratory distress should be examined in a manner that keeps them as calm as possible. Agitation and crying may worsen obstruction and increase fatigue and oxygen demand. Children should be examined in their parent's arms and anxiety provoking procedures avoided if at all possible. In particular the ear, nose and throat examination adds little value to patients with respiratory distress and may be harmful (especially in patients with suspected epiglottitis)
- Lethargy, a decreasing level of consciousness, falling oxygen saturations and a silent chest herald impending respiratory failure and probable need for urgent airway management
- The Alberta Clinical Practice Guideline Working Group, provides a clinically useful classification of croup severity:
- Mild
- Occasional barky cough
- No stridor at rest
- Mild to no increased work of breathing
- Moderate
- Frequent barky cough
- Stridor at rest
- Increased work of breathing
- Little to no distress or agitation
- Severe
- Frequent barky cough
- Prominent stridor (inspiratory or expiratory)
- Marked increased work of breathing
- Significant distress and agitation
- Impending respiratory failure
- Barky cough (may not be prominent)
- Audible stridor at rest (may be soft)
- Increased work of breathing
- Lethargy
- Decreased level of consciousness
- Dusky appearance
- The Westley scoring system uses scores for air entry, stridor, recession, cyanosis and level of consciousness to classify croup severity. It has been widely used and is a reliable and valid tool. It's clinical usefulness, as compared to the Alberta Medical Association guidelines is in no way superior, and either system is acceptable for clinical use. As with many scoring systems, there are concerns about inter-observer variability. The points in 5 areas are added, and a summative score indicates severity of croup.
- 0-2 pts = Mild croup
- 3-5 pts = Moderate croup
- 6-11 pts = Severe croup
- >11 pts = Impending respiratory failure
Chest wall retraction- None (0 pts)
- Mild (1 pt)
- Moderate (2 pts)
- Severe (3 pts)
Stridor- None (0 pts)
- Mild (1 pt)
- Moderate (2 pts)
Cyanosis- None (0 pts)
- With agitation (4 pts)
- At rest (5 pts)
Level of consciousness- Normal (0 pts)
- Disoriented/Diminished (5 pts)
Air entry- Normal (0 pts)
- Decreased (1 pt)
- Markedly decreased (2 pts)
General treatment items
- The goal of treatment is to maintain the airway and effective ventilation, administer therapies that yield symptomatic relief and decreases risk of short term recurrence. Croup is primarily managed with supportive measures, corticosteroids and, in cases of adequate severity, nebulized epinephrine
- Corticosteroids
- Corticosteroids effectively decrease mucosal edema, and should be administered to all croup patients
- Symptomatic relief may be seen within 30 minutes of administration of oral steroids, with a reduction in the croup score, rate of admission, length of hospital stay, representation and need for nebulized epinephrine
- Oral steroids (dexamethasone, prednisone, prednisolone) are preferred over nebulized budesonide, mostly due to ease of administration and availability. Nebulized budesonide is more effective than placebo, but appears less effective in some studies than systemic steroids
- In the event the child is severely unwell or unlikely to tolerate or absorb oral medication, injectable routes are favored (IV preferred, IM acceptable)
- Lower doses of dexamethasone 0.15 mg/kg as a single dose has been shown to be as effective as larger doses
- Nebulised Epinephrine
- Racemic epinephrine is the 1:1 mixture of D- and L-isomers of epinephrine. L- epinephrine (1:1,000 injectable solution) has similar efficacy. Nebulized epinephrine activates alpha and beta adrenergic receptors which leads to bronchodilation, constriction of capillary arterioles and a decrease in mucosal edema
- Nebulized epinephrine should be used in all children with severe croup, and in most children with moderate croup. It provides symptomatic relief within minutes and has effects which usually last 1-3 hours
- Supportive measures
- Oxygen maybe required to maintain saturations
- Intravenous access and fluids should be avoided if possible as it has the potential to cause agitation and increase respiratory distress. It should be considered only in children with severe respiratory distress who are unable to tolerate oral fluids
- Ineffective treatments
- Mist therapy has historically been used to treat croup however there is no evidence of benefit and the intervention may in-fact be harmful
- A mixture of helium and oxygen has been used in patients with impending respiratory failure. Helium is an inert gas and its low density and viscosity was thought to improve laminar flow in an obstructed airway. No improvement has been demonstrated in studies
- Antibiotics are usually not relevant as almost all cases are viral in origin
- Antitussives and decongestants have no role in the management of croup
Medications indicated with specific doses
Corticosteroids
- Budesonide [Inhaled]
- Dexamethasone [Oral]
- Dexamethasone [IM/IV]
- Methylprednisolone [Injectable]
- Prednisone
- Prednisolone [Oral]
- Epinephrine, racemic [Inhaled]
- L-epinephrine (Epinephrine 1:1,000 injectable solution) nebulized: 0.5 mg/kg nebulized, maximum 5 mg [5 mL of 1:1,000 solution]/dose. May need to be repeated if clinical situation requires (typically not more frequently than q1-2 hr). It is important to note that nebulized epinephrine may need to be administered significantly more frequently than the recommended intervals in severe/critical cases
Dietary or Activity restrictions
- Small frequent feeds should be encouraged to maintain hydration state
Disposition (Admission and Discharge criteria)
Admission Criteria
- Persistent respiratory compromise 4 hours post steroid administration
- Need for recurrent epinephrine nebulization
- Recurrent emergency department presentations
- Difficult social circumstances or remote living conditions
Discharge Criteria - Mild-moderate symptoms on presentation
- No stridor at rest and no accessory muscle use 30 minutes post steroids
- If epinephrine was administered, observation for 3-4 hours following this, and examination findings of no stridor at rest and no accessory muscle use
- Adequate oral intake
- Good social supports
- No concern about another concerning diagnosis as etiology for the symptoms
