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Study: Cold outdoor air coupled with steroids helps croup symptoms

August 1, 2023

Using cold outdoor air to help relieve children’s croup symptoms now has more than just anecdotal evidence of a benefit.

A new randomized, controlled trial found the practice can help when used alongside steroids.

“Considering that oral dexamethasone shows a therapeutic effect after a 30 minute-delay, this nonpharmacological additional measure, easy to perform by parents and guardians, could be an initial measure to offer,” authors wrote in “Outdoor Cold Air Versus Room Temperature Exposure for Croup Symptoms: A Randomized Controlled Trial” (Siebert JN, et al. Pediatrics. Aug. 1, 2023).

Croup is a common childhood illness characterized by a barking cough that often occurs at night. The standard treatment is dexamethasone, which takes effect in about 30 minutes. Parents have reported benefits of cold outdoor air and some physicians recommend it, but there has been little study of the practice.

To test its impact, researchers conducted a randomized, controlled trial with 118 children at a pediatric emergency department. Patients were ages 3 months to 10 years and had a Westley Croup Score (WCS) of 2 or higher. Each received a single dose of oral dexamethasone and then were randomized to be exposed to 30 minutes of outdoor air below 50 degrees Fahrenheit or to spend that time indoors.

After 30 minutes, 49% of the outdoor group and 24% of the indoor group saw their WCS score decrease by at least two points. The greatest benefit was seen for those with moderate croup, and there was no clinically significant difference in pulse oximetry between the indoor and outdoor groups.

Seven days later, 44% of the outdoor group and 32% of the indoor group reported symptoms had resolved completely.

Authors posed several theories as to why the cold outdoor air helps croup symptoms. They said it may stimulate receptors in the upper airway, which “has been shown to both mediate ventilatory depression and increase upper airway dilator muscle activity, thus reducing laryngeal and supraglottic upper airway resistance.” The cold also may reduce laryngeal mucosal blood flow, resulting in less mucosal thickness. They do not believe differences in humidity factored into the effects.

Authors also noted that 60 minutes after the dexamethasone, the number of patients who significantly improved was the same in the indoor and outdoor groups. They called for more studies and suggested using digital auscultation and blinding the physician in charge from knowing which children had been outside so that knowledge could not impact the results.


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