Effects of different high-flow nasal cannula flow rates on swallowing function

Background: High-flow nasal cannula therapy is used as a noninvasive treatment for people with acute respiratory disease. The aim of this study was to assess the impact of high-flow nasal cannula different flow rates on different characteristics of swallowing in healthy volunteers. Methods: A prospective cohort study where healthy adult volunteers were subject to high-flow nasal cannula at different flow rates (0, 10, 20, 30, 40, and 50 L/min, in random order). The 30-mL water swallow test, repetitive saliva swallowing test, and 0-100 mm visual analog scale assessed aspiration, swallow frequency and effort, respectively. Findings: Thirty subjects (mean age 30 years) were enrolled. Nine subjects (30.0%) choked at 10, 40 and 50 L/ min during the 30-mL water swallow test (p < 0.05). Swallowing effort was increased during flow rates >20 compared to 10 L/min (p < 0.05). Flow rates >20 L/min resulted in lower number of swallows during the repetitive saliva swallowing test compared to 0 and 10 L/min (p < 0.05). Interpretation: High-flow nasal cannula flow rates above 40 L/min associated with choking (increased risk of aspiration), and was associated with decreased swallowing function in healthy volunteers. It may be important to assess swallowing function in patients with various clinical conditions and treated with high-flow nasal cannula, especially those at risk of aspiration pneumonia.