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

Background High-flow nasal therapy (HFNT) is widely used in patients with respiratory failure in different clinical settings, but the effect of HFNT on respiratory-swallow coordination is unknown. Understanding this relationship is crucial, considering the necessity for patients to maintain adequate nutrition during daytime HFNT. Purpose This scoping review aims to synthesise available data on the effects of HFNT 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 May 30th, 2023, for studies reporting data on swallowing assessment in healthy adults or patients with acute or chronic respiratory failure receiving HFNT. Data on study design, patients’ characteristics, and quality outcomes were extracted, and risk of bias was assessed. 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 HFNT; two studies showed that patients’ overall clinical picture and underlying medical conditions influence swallowing-breathing coordination rather than HFNT per se. Risk of bias was judged low for all the included studies. Conclusion This scoping review found limited and controversial evidence of the impact of HFNT on swallowing function. Remarkably, methods for swallowing function assessment were quite heterogeneous. Additional research is required to test the effect of HFNT on respiratory-swallowing coordination.