Viral Croup: A Current Perspective

Alexander K.C. Leung, MBBS, FRCPC, FRCP (UK & Irel), FRCPCH; James D. Kellner, MD, FRCPC; David W. Johnson, MD, FRCPC


J Pediatr Health Care. 2004;18(6) 

In This Article


Treatment depends on the severity of the illness and may include any or all of the following modalities: general supportive measures, corticosteroids, nebulized epinephrine, supplemental oxygen, and endotracheal intubation.

It is important to maintain a calm and reassuring atmosphere for the parents and child (Respiratory Committee of the Paediatric Society of New Zealand, 1995). Most children can be managed effectively at home. Antipyretics should be given if the child is febrile. Adequate hydration should be maintained. The use of mist therapy, although traditional, is of unproven value (Bourchier, Dawson, & Fergusson, 1984; Neto, Kentab, Klassen, & Osmond, 2002). At best, it works like a placebo to make the parents feel that they are doing something for the child (Chandler, 2002). At worse, such treatment may be anxiety provoking. Randomized, controlled trials evaluating mist therapy in croup did not demonstrate any benefit in using a humidified atmosphere when compared with room air (Bourchier et al., 1984; Neto et al., 2002). As such, the use of mist therapy is not justified.

Corticosteroids are the mainstay of therapy for croup. Corticosteroids have potent vasoconstrictive and anti-inflammatory properties (Ewig, 2002). Corticosteroids reduce airway inflammation, vascular permeability, and mucosal edema (Malhotra & Krilov, 2001). During the past decade, multiple randomized, placebo-controlled trials and meta-analyses have established benefits from corticosteroid treatment with respect to improvement of croup scores, decreased rates of return to the health care practitioner and emergency department for persistent symptoms, reduced length of observation in emergency department, decreased hospitalization rates, shorter hospital stays, and decreased need for more intensive ventilatory support (Ausejo et al., 1999; Osmond, 2002; Rittichier & Ledwith, 2000; Rowe, 2002). Good evidence now exists to support to use of steroids in the management of severe, moderate, or even mild croup (Bjornson et al., 2004; Geelhoed, Turner, & Macdonald, 1996). In a recent multicenter, double-blind, randomized, placebo- controlled trial of 720 children with mild croup, those treated with dexamethasone, compared with placebo, had half the rate of return to a health care practitioner (7% versus 15%), more rapid resolution of croup symptoms, less lost sleep, and less parental stress (Bjornson et al.).

The most frequently studied corticosteroids are dexamethasone, given orally or intramuscularly, and budesonide, given by nebulization. Dexa-methasone is a potent corticosteroid with an anti-inflammatory effect ten times that of prednisone (Folland, 1997; Klassen & Rowe, 1996). Budesonide is a synthetic glucocorticoid with relatively strong topical anti-inflammatory effects and low systemic activity compared with beclomethasone (Folland). Both systemic dexamethasone (oral or intramuscular) and nebulized budesonide have been found to be equally effective (Ausejo et al., 1999; Geelhoed & Macdonald, 1995; Johnson et al., 1998; Osmond, 2002; Ritticher & Ledwith, 2000; Rowe, 2002). Oral dexamethasone is preferred because it is inexpensive, easy to administer, readily available, and relatively well tolerated (Fitzgerald & Kilham, 2003; Griffin et al., 2002; Klassen et al., 1998). Administering dexamethasone intramuscularly is painful and administration of nebulized budesonide can be distressing. As such, intramuscular dexamethasone or nebulized budesonide should be reserved for children unable or unwilling to take the oral form (Ewig, 2002; Rittichier & Ledwith, 2000). The potential for adverse effects following a single dose of systemic dexamethasone is extremely low, and safety is generally not a issue. However, the medication should be used with caution in children with known immune deficiency or recent exposure to chickenpox (Folland, 1997; Jaffe, 1998; Johnson, 2004).

The traditional dose of dexamethasone is 0.6 mg/kg (Johnson, 2004; Malhotra & Krilov, 2001). There is conflicting evidence regarding whether smaller doses of steroid are as effective as the traditional dose. A systematic review found that the higher the dose of corticosteroid administered, the greater the difference in the proportion of children reported to have improvement between the corticosteroid and placebo groups (Geelhoed & MacDonald, 1995). In contrast, a small randomized controlled trial found no significant difference between single oral dexamethasone doses of 0.6 mg/kg versus 0.3 mg/kg versus 0.15 mg/kg in children with mild to moderate croup (Kairys, Olmstead, & O'Connor, 1989). The dosage of nebulized budesonide most frequently used is 2 mg (Ewig, 2002). So far, there have been no published data on whether multiple doses of corticosteroids provide greater benefit than a single dose (Johnson, 2004).

Racemic epinephrine is a 1:1 mixture of the dextrorotatory (D) and levorotatory (L) isomers of epinephrine, of which the L form is the active component (Cressman & Myer, 1994; Malhotra & Krilov, 2001). Racemic epinephrine works by stimulation of the α-adrenergic receptors in the airway with resultant mucosal vasoconstriction and decreased subglottic edema and by stimulation of the β-adrenergic receptors with resultant relaxation of the bronchial smooth muscle (Cressman & Myer 1994; Thomas & Friedland, 1998). Randomized studies comparing racemic epinephrine with either placebo or no treatment have shown significant improvements in croup scores in the treated patients versus the controls (Kristjansson, Berg-Kelly, & Winso, 1994; Ledwith, Shea, & Mauro, 1995). The recommended dose is 0.5 mL of a 2.25% of racemic epinephrine diluted in 2 to 3 mL of normal saline solution (Cressman & Myer 1994; Folland, 1997). L-epinephrine appears equally effective with no additional adverse effects (Waisman et al., 1992). The recommended dose of L-epinephrine is 5 mL of a 1:1,000 solution diluted in 2 to 5 mL of saline solution. The onset of action is 10 to 30 minutes and the duration of action is approximately 2 hours, at which time patients return to their baseline severity. Adverse effects of nebulized epinephrine include tachycardia and circumoral pallor. Although the simultaneous use of corticosteroid helps to reduce the rebound phenomenon and obviates the need for hospitalization, patients still should be observed for a minimum of 2 hours following treatment (Rizos, DiGravio, Sehl, & Tallon, 1998). Nebulized epinephrine should be reserved for children with moderate to severe croup and should be used with caution in children who have tachycardia or ventricular outlet obstruction (Malhotra & Krilov, 2001). Hospitalization should be considered in children who have stridor at rest with associated chest-wall indrawing after a period of observation (a minimum of 3 hours and optimally 8 to 12 hours).

Supplemental oxygen should be given for children with significant oxygen desaturation (pulsatile oxygen saturation <90%) (Fitzgerald & Kilham, 2003). Clinically, this is manifested by tachycardia, tachypnea, labored breathing, agitation, cyanosis, and deteriorating clinical state. Children given supplemental oxygen should be monitored by oximetry. The use of a mixture of helium and oxygen may improve ventilation (Malhotra & Krilov, 2001). Helium is an inert, non-toxic, low density gas which can potentially decrease turbulent airflow in a narrow airway (Johnson, 2004). There is, however, insufficient evidence to justify its routine use (Johnson).

Endotracheal intubation with or without assisted ventilation is rarely required except for those who have impending respiratory failure despite administration of effective doses of corticosteroids and epinephrine.


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