Croup in the paediatric emergency department

Abstract

Croup is a common childhood illness. The majority of children presenting with an acute onset of barky cough, stridor and indrawing have croup. A careful history and physical examination is necessary to confirm the diagnosis of croup, and to rule out potentially serious alternative causes of upper airway obstruction. Nebulized adrenaline is effective for the temporary relief of airway obstruction. Corticosteroids are the mainstay of treatment in children with croup of all levels of severity.

Croup (laryngotracheobronchitis) is a common cause of upper airway obstruction in children. The annual incidence is 1.5 to 6 per 100 children younger than six years of age (1). Croup is most prevalent in the late fall to early winter months. Although common in children between six months and three years of age, it can also occur in children as young as three months and as old as 15 years of age (1). It is rarely reported in adults (2). Boys are affected more often than girls. Common causes are parainfluenza types 1 and 3. Influenza A and B, adenovirus, respiratory syncytial virus, metapneumovirus and mycoplasma have also been isolated (1,3).

Croup is a clinical diagnosis requiring no specific laboratory or radiological investigations when the history and physical examinations are typical (Table 1). Particular attention should be paid to symptoms such as nonspecific cough, rhinorrhea and fever, which may precede the characteristic seal-like barky cough. Symptoms are usually worse at night, and are aggravated by agitation and crying. Obstructive symptoms generally resolve within 48 h, but a small percentage of children remain symptomatic for up to five to six days (4). Physical findings include stridor, chest wall retractions and respiratory distress ranging from mild to severe. Signs of respiratory failure include reduced respiratory effort and breath sounds, lethargy, and pallor or cyanosis. Severity of croup may be broadly categorized by clinical observation (Table 2).

TABLE 1.

Differential diagnoses for children who present with acute onset of stridor

Differential diagnosis	Characteristics
Bacterial tracheitis (most common diagnosis after croup)	High fever, toxic appearance and poor response to nebulized adrenaline.
Epiglottitis (relatively rare since introduction of Haemophilus influenzae type b vaccine)	Absence of barky cough, sudden onset of high fever, dysphagia, drooling, toxic appearance, anxious appearance and sitting slightly forward in the ‘sniffing’ position.
Occult foreign object (very rare)	Acute onset of stridor and presence of occult foreign body most commonly lodged in the upper esophagus.
Laryngeal diphtheria (very rare)	History of inadequate immunization may be found. Prodrome of pharyngitis 3 days. Low-grade fever, hoarseness, barking cough, stridor and dysphagia. Characteristic membranous pharyngitis on examination.
Acute allergic reaction or angioneurotic edema (rare)	Rapid onset of dysphagia and stridor, and possible cutaneous allergic signs such as urticarial rash.

TABLE 2.

Classification of severity of croup at time of initial assessment

Mild	Moderate	Severe
Without stridor or significant chest wall indrawing at rest	Stridor and chest wall indrawing at rest without agitation	Stridor and indrawing of the sternum associated with agitation or lethargy

Data from reference 7

The majority of children can be safely managed at home. Very few require artificial airway support (5). Over 60% of children diagnosed with croup have mild symptoms, approximately 4% are hospitalized and approximately one in 5000 children are intubated (approximately one in 200 hospitalized children) (4–6).

Goals of therapy are to decrease the duration and severity of symptoms, minimize anxiety of the child and his/her parents, and to decrease intubations, hospitalizations and return visits to physicians.

THERAPEUTIC OPTIONS

Children with mild croup can be managed in the office setting, while those with moderate or severe croup should be referred to an emergency department for treatment and observation (Figure 1).

NONPHARMACOLOGICAL CHOICES

Keep children calm by ensuring a relaxed and reassuring atmosphere to minimize oxygen demand and respiratory muscle fatigue. There is insufficient evidence to support the use of mist therapy (7–14). Placing children in mist tents, a wet and cold environment, and separating them from their parents may provoke anxiety and agitation and should be avoided (13).

Oxygen therapy, in conjunction with corticosteroids and adrenaline, is reserved for children with hypoxia and significant respiratory distress. It should never be forced on a child, especially if it results in significant agitation. ‘Blow-by’ administration of oxygen through a plastic hose with the end opening held within a few centimeters of the child’s nose and mouth is often the most beneficial way of administration. Helium-oxygen mixtures may benefit children with severe respiratory distress (15–18), but there is insufficient evidence to advocate their use outside this setting. Administration of helium-oxygen mixtures has been proposed because there is a potential for the lower density helium gas (relative to nitrogen) to decrease turbulent airflow in a narrowed airway. Practical limitations include the limited fractional concentration of inspired oxygen in a child with significant hypoxia.

PHARMACOLOGICAL CHOICES (TABLE 3)

TABLE 3.

Drugs used for croup

Drug class	Drug	Dose and duration	Comments	Cost*
Adrenergic agonist	Adrenaline, racemic Vaponefrin (sanofiaventis, Canada)	0.5 mL of 2.25% solution diluted in 2.5 mL of normal saline or sterile water via nebulizer	Racemic adrenaline and L-adrenaline are equivalent in terms of effect and safety (53). Adrenaline has no effect on clinical symptoms beyond 2 h, consequently patients should not be discharged from medical care before 2 h following treatment (51,52).	$
	L-adrenaline generics	5 mL of 1:1000 (1 mg/mL) solution via nebulizer	See L-adrenaline, racemic.	$
Corticosteroids	Dexamethasone generics	0.15 mg/kg to 0.6 mg/kg taken orally or intramuscularly once. May repeat dose in 6 h to 24 h	Oral dexamethasone is well-absorbed and achieves peak serum concentrations as rapidly as with intramuscular administration (59) (without the pain of intramuscular injection). Several controlled trials suggest oral and intramuscular administration yield equivalent results (30,31,60). Experience suggest that clinical improvement will begin as early as 2 h to 3 h after treatment (22). No evidence to suggest that multiple doses provide additional benefit over a single dose. Reduces rate and duration of intubation, rate and duration of hospitalization and rate of return to medical care (20–29).	$
	Budesonide, Pulmicort Nebuamp (AstraZeneca Canada)	2 mg (2 mL) solution via nebulizer	Inhaled budesonide has been shown to be equivalent to oral dexamethasone in several studies (22,35,37) but is substantially more expensive. May be useful in patients with vomiting and severe respiratory distress. Can administer budesonide and adrenaline simultaneously.	$$

*Cost of one dose; includes drug cost only. $<$1; $$=$1 to $5

Corticosteroids

Corticosteroids are the mainstay of therapy for croup, regardless of clinical severity (19). Corticosteroids have been shown to reduce intubations, duration of intubation, need for reintubation, need for additional inhaled adrenaline, duration of hospitalization, rate of hospitalization and rate of return to a health care practitioner for persistent croup symptoms (20–29). Dexamethasone and inhaled budesonide relieve croup symptoms as early as 3 h after treatment (22).

Dexamethasone is equally effective when given orally (30,31). While an older meta-analysis of controlled trials (21) suggested that higher doses yield a clinically important response in a greater proportion of patients, four more recent controlled trials have found no difference in clinical outcomes between dexamethasone doses ranging from 0.15 mg/kg to 0.6 mg/kg (26,32–34). It is not known whether multiple doses of corticosteroids provide greater benefit than a single dose. Given the short duration of croup symptoms in the majority of patients, a single dose of corticosteroid may be sufficient.

It has been demonstrated that oral or intramuscular administration of corticosteroids is either equivalent or superior to the inhaled route (22,35–38). Routine use of inhaled budesonide is limited by cost. Patients with severe croup, or who are near respiratory failure, may benefit from the simultaneous administration of inhaled budesonide and nebulized adrenaline. The combination may be more effective than adrenaline alone.

Corticosteroids should be avoided in children with a known immunodeficiency or recent exposure to varicella (39–42).

Adrenaline (adrenergic agonist)

Based on historical data, nebulized adrenaline in children with severe croup substantially reduces the number requiring an artificial airway (43). Adrenaline reduces respiratory distress within 10 min of administration and lasts longer than 1 h (44–46).

Effects of adrenaline wear off within 2 h of administration (44). Although patients treated with adrenaline may return to their ‘baseline’ severity, they do not routinely develop worse symptoms (44,46). Both retrospective and prospective studies (22,47–52) suggest that patients treated with adrenaline may be safely discharged if their symptoms do not recur for at least 2 h to 3 h after treatment.

L-adrenaline 1:1000 is as effective and safe as the racemic form (53). A single-size dose (0.5 mL of 2.25% racemic adrenaline or 5 mL of L-adrenaline 1:1000) is used in all children regardless of size. Children’s relative size of tidal volume is thought to modulate the dose of drug actually delivered to the upper airway (54–57).

There is one report (58) of an otherwise normal child with severe croup treated with three nebulizations of adrenaline within 1 h who developed ventricular tachycardia and a myocardial infarction. If back-to-back adrenaline is considered necessary, the treating physician should contact a paediatric intensivist as soon as possible regarding further treatment and transport.

Analgesics

Analgesics may provide some degree of increased comfort by reducing fever and pain.

Antitussives and decongestants

No experimental studies have been published regarding the potential benefit of antitussives or decongestants in children with croup. There is no rational basis for their use.

Antibiotics

Antibiotics are not effective in the treatment of croup but may be used in suspected cases of bacterial superinfection. Intravenous antibiotics are generally recommended because of the potential for rapid deterioration.

Figure 1.

Croup in the outpatient setting (based on severity of initial assessment). ICU Intensive care unit