Effects of high-flow nasal therapy on swallowing function: a scoping review

Background High-flow nasal therapy is widely used in patients with respiratory failure in different clinical settings, but the effect of high-flow nasal therapy on respiratory-swallow coordination is unknown. Understanding this relationship is crucial, considering the necessity for patients to maintain adequate nutrition during daytime high-flow nasal therapy. This scoping review aims to synthesise available data on the effects of high-flow nasal therapy flow rates on swallowing function and the possible risk of aspiration during treatment, focusing on knowledge and evidence gaps.Methods PubMed, Scopus, Web of Science and Google Scholar databases were searched from inception to 30 May 2023 for studies reporting data on swallowing assessment in healthy adults or patients with acute or chronic respiratory failure receiving high-flow nasal therapy. Data on study design, patients' characteristics and quality outcomes were extracted.Results Eight studies were included, four including cohorts of healthy volunteers (n=148) and four including patients with acute or chronic respiratory failure (n=151). Study designs, patient populations and quality outcome measures were heterogeneous. Two studies indicated improvement while four articles showed impairment in swallowing function during high-flow nasal therapy; two studies showed that patients' overall clinical picture and underlying medical conditions influenced swallowing-breathing coordination rather than high-flow nasal therapy per se.Conclusion This scoping review found limited and controversial evidence on the impact of high-flow nasal therapy on swallowing function. Remarkably, methods for swallowing function assessment were quite heterogeneous. Additional research is required to test the effect of high-flow nasal therapy on respiratory-swallowing coordination.