The Impact of High-Flow Nasal Cannula on Swallow Function

Abstract

Background: High-flow nasal cannula (HFNC) is a noninvasive device that delivers heated and humidified gas at flows exceeding patient inspiratory demand. HFNC is used as an alternative to conventional oxygen therapy and noninvasive ventilation. HFNC’s value is not limited to ventilation and oxygenation, as it may also allow for oral feeding. At this time, HFNC’s impact on swallowing is unknown. One measure of swallowing function is spontaneous swallowing frequency (SSF), the rate at which individuals swallow their own saliva. This study investigated the impact of HFNC on SSF in healthy adults.

Methods: Heated (37°C) and humidified room air gas was delivered via the AIRVO 2 HFNC system. SSF was measured via the KayPentax Digital Swallowing Workstation (DSW) with integrated signals lab. To measure SSF, a submentally placed surface electromyography (sEMG) electrode captured swallowing muscle electrical activity. When a spontaneous swallow occurred, a large spike was recorded on the sEMG waveform. Visual confirmation of a swallow was also marked on the waveform. SSF was measured during baseline (no flow) and 3 experimental flow conditions: 30, 45, and 60 L/min. For each condition, participants sat quietly for 10 minutes while the DSW recorded all sEMG activity. Baseline rate was determined first followed by the experimental rates in randomized order. After each experimental session, HFNC was removed for 10 minutes. Summary statistics were used to describe participant characteristics; repeated measures ANOVA was used to analyze SSF among flow conditions.

Results: Participants included 18 healthy adults aged 21-83 (SD=16.10) years. Since SSF is known to decline with age, the three older participants were analyzed separately. Among the younger participants, group mean SSF scores descriptively increased as flow increased [SSF baseline = 1.12 (SD=0.75); 30 L/min=1.13 (SD=0.79); 45 L/min=3.91 (SD=10.26) swallows/minute], until the 60 L/min flow. At 60 L/min, SSF decreased to lower than baseline [SSF=1.01 (SD=0.67) swallows/minute]. No statistically significant difference in SSF was found. SSF results for the three older adults (aged 55, 65, 83 respectively) showed the same pattern.

Conclusions: Among healthy adults, regardless of age, SSF was not significantly affected by HFNC at any flow. Future studies are warranted to determine if HFNC impacts other swallow function measures.