I have seen a lot of children with croup in my career. I cannot tell you how many times I have had parents tell me that the breathing had gotten really bad, but after the trip (usually in the winter) to the office or the emergency department, the breathing was much better. “I know she looks okay now, but she was really having trouble breathing! Honestly!”
I was taught as a resident that taking the child outside in the cold air can often help with croup. But I never saw any published evidence to that effect.
I love randomized controlled trials, so to see the title, “Outdoor Cold Air vs Room Temperature Exposure for Croup Symptoms: A Randomized Controlled Trial” was exciting. This article, by Dr. John Siebert and colleagues from the University of Geneva in Switzerland, along with an accompanying video abstract, is being early released by Pediatrics this week (10.1542/peds.2023-061365).
This study is so simple, it seems remarkable that it has not been done before. The authors included 118 children aged 3 months to 10 years who presented to a pediatric emergency department if they had moderate-severe croup (measured by a Westley Croup Score [WCS] of 2 or greater) and if the outside temperature was <10 degrees Celsius (or <50 degrees Fahrenheit). Children who had croup symptoms severe enough to require nebulized epinephrine were not included in the study.
After the children underwent triage (including pulse oximetry, respiratory rate, heart rate, and baseline WCS) and received one 0.6 mg/kg dose of oral dexamethasone, they either waited for 30 minutes inside or outside the emergency department. All children were in sight of the triage desk. Vital signs and WCS were reassessed at 30 and 60 minutes. The outcome measure was any change in the WCS.
Nearly half (49.2%) of the outdoor cold air group had a decrease of at least 2 points in the WCS at 30 minutes, compared with 23.7% of the indoor group. At 60 minutes, there were no significant differences in the 2 groups, but the authors speculate that this is likely either because of steroid effect or because the benefit of cold air exposure is short-lived.
You will want to read the entire article, in which the authors describe other outcome measures and discuss the possible physiologic effects of the cold air. You’ll also feel good that your advice to take the child outside is evidence-based.
