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Myth Bust – Does Croup Really Get Better in Cold Air?

August 30, 2023

Written by Clay Smith

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Is taking a croupy child outdoors in the cold air a myth or evidence-based practice? Turns out, the RCT shows it actually works!

Not much cold outside air right now…but the concept makes sense
Dexamethasone and nebulized racemic epinephrine are the core treatments for croup. Mist doesn’t hurt but also doesn’t help. What about cool air?

This was an unblinded RCT, with 118 children with at least mild croup. Westley Croup Scores (WCS) were obtained at baseline, and they received dexamethasone. They were randomized to wait in a monitored outdoor area <10°C (<50°F) or an indoor room temperature environment for 30 minutes. WCS decreased by ≥2 points in 29/59 (49.2%) in the outdoor group and 14/59 (23.7%) in the room temperature group: risk difference 25.4% (95%CI 7.0-43.9), p = 0.007). The effect was more pronounced in patients with moderate symptoms (WCS 3-5).

The trial is at risk of expectation bias, being unblinded. Maybe they really wanted cool air to work and subconsciously rated those children as more improved. Also, patients had to thread the needle of severity – not too sick to need immediate racemic epi but not too mild to be unable to show a 2-point benefit. The setting was wintertime in Switzerland. This clearly wouldn’t work during a Nashville summer! It is also a big ask for families to wait outside when it’s cold. However, taking a child outdoors into cool air is simple, and for many places in the world, achievable in the right season of the year. Since croup is more common when it’s colder outdoors, that works out well. Overall, with a NNT = 4, this is a pretty cool intervention.

How will this change my practice?
I see this trial impacting pediatricians who take calls during the night and are trying to help parents avoid an ED visit. I also see it as a key talking point in our discharge instructions for mild recurrences at home. For warmer parts of the world, holding a freezer door open for 30 minutes is probably not feasible. One idea would be to jump in a car, turn the AC all the way down, and place the child in front of the cold air vent, which would expose them to air <10°C.

Outdoor Cold Air Versus Room Temperature Exposure for Croup Symptoms: A Randomized Controlled Trial. Pediatrics. 2023 Aug 1;e2023061365. doi: 10.1542/peds.2023-061365. Online ahead of print.

What are your thoughts?