Original Investigation 

Caring for the Critically Ill Patient

Prone Positioning in Infants With Acute Bronchiolitis: The PROPOSITIS Randomized Clinical Trial

Florent Baudin, Robin Pouyau, Fabien Subtil, et al

JAMA 2026;336;(4):315-322. doi:10.1001/jama.2026.11078

Key Points

Question  Does prone positioning reduce escalation of respiratory support in infants aged 6 months or younger with moderate to severe bronchiolitis receiving high-flow nasal cannula support?

Findings  In this randomized clinical trial, escalation of care occurred in 33 of 220 infants (15.0%) in the prone position group and 47 of 226 (20.8%) in the supine position group; the difference was not statistically significant. Serious adverse events were rare in both groups.

Meaning  Prone positioning did not significantly reduce escalation of care in infants with bronchiolitis, but this study was not definitive and further research is warranted.

Abstract

Importance  Prone positioning has been shown to improve respiratory mechanics and oxygenation, but its clinical benefit in infants with acute viral bronchiolitis receiving high-flow nasal cannula (HFNC) support remains unknown.

Objective  To investigate whether prone positioning in infants with moderate to severe acute bronchiolitis and HFNC support reduces escalation to noninvasive or invasive ventilation.

Design, Setting, and Participants  Multicenter, randomized, open-label trial conducted in 15 pediatric intermediate or intensive care units in France. Infants aged 6 months or younger admitted for 24 hours or less with a diagnosis of acute bronchiolitis with moderate to severe respiratory distress requiring HFNC support were enrolled between January 2021 and November 2023 and followed up until hospital discharge (last patient discharged on December 11, 2023).

Interventions  Participants were randomly assigned to the prone position (n = 221) or supine position (n = 230). Infants in the prone position group received prone positioning for 24 hours or longer during the first 48 hours. All participants received standardized HFNC support at 2 L/kg/min.

Main Outcomes and Measures  The primary outcome was the need for escalation of care to noninvasive or invasive ventilation within the first 72 hours, according to prespecified criteria. Secondary outcomes included treatment failure, determined by an independent clinical adjudication committee; tolerance of prone positioning; length of hospital stay; duration of respiratory support; infant comfort; and adverse events.

Results  Among 451 infants randomized, 446 were included in the primary analysis (median age, 41 [IQR, 19-72] days; 54% male). Escalation of care occurred in 80 infants (17.9%), with no significant difference between the prone position (33/220 [15.0%]) and supine position (47/226 [20.8%]) groups (adjusted odds ratio, 0.66 [95% CI, 0.40-1.07]; P = .09). Secondary outcomes did not differ significantly between the 2 groups. In the safety analysis, serious adverse events occurred in 2 of 180 infants (1.1%) in the prone position group and 2 of 264 (0.8%) in the supine position group.

Conclusions and Relevance  Prone positioning in infants with moderate to severe bronchiolitis receiving HFNC support did not significantly reduce escalation of care. However, the wide 95% confidence interval around the observed odds ratio suggests that this study was not definitive and further research is warranted.

Trial Registration  ClinicalTrials.gov Identifier: NCT03976895