In cardiac surgery patients with pre-extubation PaO2/inspired oxygen fraction (FiO2) < 200 mmHg, the possible benefits and optimal level of high-flow nasal cannula (HFNC) support are still unclear; therefore, we compared HFNC support with an initial gas flow of 60 or 40 L/min and conventional oxygen therapy. Ninety nine patients were randomly allocated (respective ratio: 1:1:1) to I = intervention group 1 (HFNC initial flow = 60 L/min, FiO2 = 0.6), intervention group 2 (HFNC initial flow = 40 L/min, FiO2 = 0.6), or control group (Venturi mask, FiO2 = 0.6). The primary outcome was occurrence of treatment failure. The baseline characteristics were similar. The hazard for treatment failure was lower in intervention group 1 vs. control (hazard ratio (HR): 0.11, 95% CI: 0.03-0.34) and intervention group 2 vs. control (HR: 0.30, 95% CI: 0.12-0.77). During follow-up, the probability of peripheral oxygen saturation (SpO2) > 92% and respiratory rate within 12-20 breaths/min was 2.4-3.9 times higher in intervention group 1 vs. the other 2 groups. There was no difference in PaO2/FiO2, patient comfort, intensive care unit or hospital stay, or clinical course complications or adverse events. In hypoxemic cardiac surgery patients, postextubation HFNC with an initial gas flow of 60 or 40 L/min resulted in less frequent treatment failure vs. conventional therapy. The results in terms of SpO2/respiratory rate targets favored an initial HFNC flow of 60 L/min.
Keywords: cardiac surgery; high-flow nasal cannula; oxygenation; respiratory rate; treatment failure.