High-Flow Therapy by Nasal Cannulae Versus High-Flow Face Mask in Severe Hypoxemia After Cardiac Surgery: A Single-Center Randomized Controlled Study-The HEART FLOW Study

Abstract

Objective: To determine whether high-flow oxygen therapy by nasal cannulae (HFNC) is more effective than a high-flow face mask (HFFM) in severe hypoxemia.

Design: Randomized, single-center, open-labeled, controlled trial.

Setting: University Hospital of Nantes, France.

Participants: Cardiac surgery patients presenting oxygen saturation <96% with Venturi mask 50%.

Intervention: Oxygenation by HFNC (45 L/min, F_IO₂ 100%) or Hudson RCI non-rebreather face mask with a reservoir bag (15 L/min).

Measurements and main results: The co-primary outcomes were the PaO₂/F_IO₂ ratio at 1 and 24 hours. In the intent-to-treat analysis (90 patients), the mean (standard deviation) PaO₂/F_IO₂ ratios were: after 1 hour, 113.4 (50.2) in HFFM versus 137.8 (57.0) in HFNC (mean difference 24.4, CI 97.5% [2.9-45.9], p = 0.03), and after 24 hours, 106.9 (62.6) in HFFM versus 129.9 (54.0) in HFNC (mean difference 23.0, CI 97.5% [1.5-44.6], p = 0.04). After adjustment on baseline PaO₂/F_IO_2, this difference persisted at 24 hours (p = 0.04). For secondary outcomes, the PaO₂/F_IO₂ ratio after 6 hours was 108.7 (47.9) in HFFM versus 136.0 (45.2) in HFNC (p = 0.01), without difference after 48 hours (p = 0.95). Refractory hypoxemia requiring noninvasive ventilation occurred in 13 (28%) patients in HFNC versus 24 (56%) patients in HFFM (p = 0.007). The HFNC improved satisfaction (p = 0.0002) and reduced mucus dryness (p = 0.003) compared with HFFM.

Conclusion: In patients with severe hypoxemia after cardiac surgery, PaO₂/F_IO₂ at 1 and 24 hours were higher and the use of noninvasive ventilation was reduced in HFNC compared with HFFM.

Keywords: acute respiratory failure; cardiac surgery; coronary artery bypass; high-flow oxygen therapy by nasal cannulae; hypoxemia; noninvasive ventilation.