Clinical question: Does high-flow oxygen therapy result in a decreased rate of intubation for patients with nonhypercapnic acute hypoxemic respiratory failure?
Bottom line: In this underpowered study, the use of high-flow oxygen therapy did not significantly reduce the rate of intubation as compared with standard oxygen therapy or noninvasive positive pressure ventilation in patients with nonhypercapnic acute hypoxemic respiratory failure. However, patients in the high-flow oxygen group had decreased 90-day mortality, as well as an increased number of ventilator-free days. Patients in the high-flow oxygen group also reported less respiratory discomfort and dyspnea than patients in the other 2 groups. (LOE = 1b-)
Reference: Frat J, Thille AW, Mercat A, et al, for the FLORALI Study Group and the REVA Network. High-flow oxygen through nasal cannula in acute hypoxemic respiratory failure. N Engl J Med 2015;372(23):2185-2196.
Study design: Randomized controlled trial (nonblinded)
Funding source: Government
Setting: Inpatient (ICU only)
Synopsis: High-flow oxygen therapy uses oxygen delivered via nasal cannula at high flow rates to provide low-level positive pressure and reduce effective deadspace in the airways. Its effectiveness in the treatment of acute hypoxemic respiratory failure has not been established. In this study, investigators compared high-flow oxygen therapy with noninvasive positive pressure ventilation as well as with standard oxygen therapy in patients with nonhypercapnic acute hypoxemic respiratory failure.
Using concealed allocation, patients were randomized into 1 of 3 groups: (1) standard oxygen therapy using a nonrebreather face mask at a flow rate of 10 liters per minute or more; (2) high-flow oxygen therapy provided through a heated humidifier at a rate of 50 liters per minute for at least 2 days; or (3) noninvasive positive pressure ventilation for 8 hours per day for at least 2 days. With all 3 strategies, the goal was to maintain an oxygen saturation level of 92% or more. The 3 groups were similar at baseline with the majority of patients having community-acquired pneumonia as a cause of their acute respiratory failure. Analysis was by intention to treat.
For the primary outcome, the high-flow oxygen therapy group had a lower rate of intubation at 28 days than the other 2 groups, but this difference was not statistically significant (38% in high-flow group, 47% in standard group, 50% in noninvasive ventilation group; P = .18). Of note, the intubation rate in the standard oxygen therapy group was lower than the expected 60%, thus the study was underpowered to detect a difference if it truly exists. The high-flow therapy resulted in reduced 90-day mortality as compared with both standard therapy (hazard ratio [HR] = 2.01, 95% CI 1.01-3.99; P = .046) and noninvasive ventilation (HR = 2.50, 1.31-4.78; P = .006).
Dr. Kulkarni is an assistant professor of hospital medicine at Northwestern University in Chicago.