A multicenter randomized controlled trial of a 3-L/kg/min versus 2-L/kg/min high-flow nasal cannula flow rate in young infants with severe viral bronchiolitis (TRAMONTANE 2).

Purpose: High-flow nasal cannula (HFNC) therapy is increasingly proposed as first-line respiratory support for infants with acute viral bronchiolitis (AVB). Most teams use 2 L/kg/min, but no study compared different flow rates in this setting. We hypothesized that 3 L/kg/min would be more efficient for the initial management of these patients.

Methods: A randomized controlled trial was performed in 16 pediatric intensive care units (PICUs) to compare these two flow rates in infants up to 6 months old with moderate to severe AVB and treated with HFNC. The primary endpoint was the percentage of failure within 48 h of randomization, using prespecified criteria of worsening respiratory distress and discomfort.

Results: From November 2016 to March 2017, 142 infants were allocated to the 2-L/kg/min (2L) flow rate and 144 to the 3-L/kg/min (3L) flow rate. Failure rate was comparable between groups: 38.7% (2L) vs. 38.9% (3L; p = 0.98). Worsening respiratory distress was the most common cause of failure in both groups: 49% (2L) vs. 39% (3L; p = 0.45). In the 3L group, discomfort was more frequent (43% vs. 16%, p = 0.002) and PICU stays were longer (6.4 vs. 5.3 days, p = 0.048). The intubation rates [2.8% (2L) vs. 6.9% (3L), p = 0.17] and durations of invasive [0.2 (2L) vs. 0.5 (3L) days, p = 0.10] and noninvasive [1.4 (2L) vs. 1.6 (3L) days, p = 0.97] ventilation were comparable. No patient had air leak syndrome or died.

Conclusion: In young infants with AVB supported with HFNC, 3 L/kg/min did not reduce the risk of failure compared with 2 L/kg/min. This clinical trial was recorded on the National Library of Medicine registry (NCT02824744).