Effect of Flow Rates of High-flow Nasal Cannula on Extubation Outcomes: A Randomized Controlled Trial

Background: High-flow nasal cannula (HFNC) has emerged as a promising intervention for post-extubation oxygen therapy, with the potential to reduce the need for reintubation. However, it remains unclear whether using a higher flow setting provides better outcomes than the commonly used flow rate of 30-50 L/min.

Research question: Does setting the flow rate of HFNC at 60 L/min versus 40 L/min for post-extubation care result in different extubation outcomes?

Study design and methods: This randomized controlled trial assigned intubated patients to receive HFNC at either a 60 L/min or 40 L/min flow rate following extubation. The assigned flow rate was maintained for 24 hours. The primary outcome was a composite of reintubation or the use of non-invasive ventilation (NIV) within 48 hours post-extubation. Key secondary outcomes included ahead-of-schedule changes in HFNC settings and mortality.

Results: 180 patients were randomized, with 169 (86 in the 40 L/min group and 83 in the 60 L/min group) included in the analysis. The primary outcome events occurred in 19 patients (22.1%) in the 40 L/min group and in 14 patients (16.9%) in the 60 L/min group (risk difference 5.2% [95% CI, -6.7% to 17.1%], P = 0.39). For secondary outcomes, the 40 L/min group was associated with a higher risk of escalation in respiratory support, defined as using NIV or up-titration of HFNC settings (24 [27.9%] vs 8 [9.6%], P = 0.002).

Interpretation: In unselected extubated patients, setting the HFNC flow rate at 60 L/min did not reduce the risk of reintubation or NIV use compared to a flow rate of 40 L/min. Using a flow rate of 40 L/min with as-needed up-titration may be a reasonable alternative to setting the flow at 60 L/min for post-extubation care. However, this trial may not have been sufficiently powered to exclude a small between-group difference.

Clinical trial registration: ClinicalTrials.gov; No.: NCT04934163.