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Am Fam Physician. 2007;75(1):50

Humidified Air for Croup?

Clinical Question

Is humidified air an effective treatment for laryngotracheobronchitis (croup)?

Evidence-Based Answer

Available data do not support a clinically important benefit of humidified air for symptomatic treatment of children with croup. However, it does not appear to be harmful.

Practice Pointers

Although humidified air is recommended routinely to parents of children with croup as a way to relieve symptoms, it has not been studied well. In addition, animal studies have found that airway resistance is reduced more by warm or cool dry air than by warm moist air. The authors of this systematic review searched the literature and identified three studies with a total of 135 patients. The number of participants in each study was between 16 and 71, and the overall age range was three months to six years. All studies compared warm or cool humidified air with no treatment, took place in the emergency department or children's ward, and evaluated outcomes using a validated symptom score. The studies were generally of good quality, although only one had outcomes assessed by researchers blinded to the treatment assignment.

The authors combined symptom scores assessed at 20 to 60 minutes and found no significant benefit with humidified air. Although at 20 to 30 minutes, there was a trend toward benefit with mist; at 60 minutes, the trend favored no treatment (effect sizes = −0.4 [95% confidence interval (CI), −0.82 to 0.02] and 0.2 [95% CI, −0.64 to 1.05], respectively).

There are no standard national guidelines for the management of croup in the United States. A guideline from the Alberta Medical Association does not recommend mist therapy because it has not been shown to be effective,1 and an evidence-based guide-line from Monash University in Australia states that mist and humidified air have not been demonstrated to be effective treatments for children with croup.2 Oral dexamethasone (Decadron; 0.6 mg per kg) improves outcomes and reduces the risk of hospital admission. For severe croup with stridor, respiratory distress, or lethargy, blow-by oxygen and nebulized racemic epinephrine 2.25% (0.5 mL in 2.5 mL saline) or L-epinephrine 1:1,000 (0.5 mL) also are treatment options.

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