The Impact of High-Flow Nasal Cannula on Swallow Function
Phase: NA
Conditions: Swallowing Disorder, Respiratory Insufficiency
Sponsor: Rush University Medical Center

 
Study Title: The Impact of High-flow Nasal Cannula on Swallow Function  
 
Principal Investigator: 
J. Brady Scott, MSc, RRT, RRT-ACCS, AE-C, FAARC, FCCP 
Director of Clinical Education and Assistant Professor 
Rush University, Department of Respiratory Care 
 
Co-Investigator(s): 
Lisa LaGorio, PhD, MPH, CCC-SLP 
Assistant Professor 
 
Rush University, Department of Communication Disorders and Sciences 
 
 
Jie Li, MS, RRT-NPS-ACCS 
Clinical Education Coordinator and Assistant Professor 
Rush University, Department of Respiratory Care 
 
Hibbah Alshuwaikhat 
Respiratory Care Student  
Rush University, College of Health Sciences 
3/8/2018 
 
 

Specific Aims  
The primary aim of this research is to determine the impact of different flow rates of a 
high-flow nasal cannula on spontaneous swallowing frequency at rest and swallowing effort and 
timing while swallowing.  
Introduction 
High-flow nasal cannula (HFNC) is a non-invasive heated and humidified oxygen delivery 
device that is capable of delivering up to 60 L/min of flow.1 It is a relatively new modality that has 
been introduced as an alternative to conventional oxygen therapy in patients with chronic 
obstructive pulmonary disease (COPD)2,3, respiratory failure4,5, obstructive sleep apnea (OSA)6, 
post-extubation7-10, and status asthmaticus.11 The humidified gas preserves mucociliary function 
that prevents secretion retention and enhances patient’s comfort. This feature allows prolonged 
use of HFNC in clinical sittings of up to 30 days.12      
 In addition to its ability to provide adequate humidification levels, HFNC has various 
respiratory physiological effects. These physiological effects include: alveolar recruitment, dead 
space washout, and decreased airway resistance.12 The clinical value of the use of HFNC is not 
limited to its ventilation and oxygenation effects, it enables the patient to talk and is purported to 
permit oral feeding during oxygen therapy.13  
Currently, despite the fact that patients are often permitted to eat while receiving HFNC 
therapy, there is insufficient evidence regarding the impact of HFNC on swallow function. The 
uncertainty of the effect of this oxygen delivery device on swallow function arises not only from 
the limited number of studies, but also the contradictory results. For example, Sanuki et al. reported 
that increasing the flow rates of the HFNC resulted in enhanced swallow function by reducing 
reflex latency.14 Based on their findings, the researchers suggested that the use of HFNC should 
not affect the decision to start or resume feeding. Similarly, Lader et al. proposed that the use of 
high-flow nasal cannula should not delay oral alimentation.15 On the contrary, Ferrara et al. 
conducted a study in neonates and concluded that providing feeding while using Nasal Continuous 
Positive Airway Pressure (nCPAP) increased the risk of aspiration.16 These opposing outcomes 
support the need for further studies to obtain more definitive evidence.   

 
Spontaneous Swallowing Frequency: 
Spontaneous swallowing is an airway protection reflex and the measurement of its 
frequency is considered to be a sensitive indicator of swallow function. This index can sensitively 
identify dysphagia and other swallowing-related disorders. Furthermore, the reduction in this index 
is associated with increased level of secretions and chest infections.17 One modality used to 
measure swallowing frequency is surface electromyography (sEMG), which records electric 
activity during swallow via an electrode placed on the skin under the chin. This non-invasive 
technology has been used for more than 20 years to record various aspects of swallowing 
physiology.18,19 In this study, sEMG will be used because of its feasibility, accuracy, and ability to 
detect a swallow. 
Swallowing Effort and Timing:  
 
Swallowing effort via submental sEMG provides an objective measurement of lingual and 
sub-mental muscle activity during the act of swallowing. Measurements include muscle 
contraction amplitude and contraction timing/speed. Clinically, swallowing effort parameters have 
been used to document normative values in healthy individuals,20 as well as to document the effects 
of a disease on swallowing.21 Prior research has shown that both amplitude and timing are 
influenced by multiple factors including the volume and viscosity of the item (or bolus) being 
swallowed,22,23 and the age and gender of the person swallowing.24,25 However no study has 
investigated the effects of HFNC on either swallowing effort parameter.  
Experimental Design and methods  
This is a prospective study designed to measure swallowing frequency and swallowing 
effort in fifty healthy adult volunteers (25 participants will be between 21 and 49 years old; and 
the other 25 above 50 years old). To recruit volunteer participants, an email will be sent via 
university internal email system to the faculty, students and employees in the departments of 
Respiratory Care and Speech Language Pathology. Snowball sampling (non-probability sampling) 
will also be utilized to recruit individuals outside of those departments. No compensation is offered 
to the participants. Enrolled participants are sub-categorized into two different age groups to 

determine if there are any swallowing differences between the different age groups. Inclusion 
criteria include individuals who are older than 21 years of age and have no cognitive impairment. 
Exclusion criteria include individuals who are less than 21 years of age, have a history of dysphagia 
or disease/condition that may cause dysphagia, current use of medications that alter swallowing 
function, nasal obstruction, and the presence of a tracheostomy tube.  
Upon meeting inclusion criteria, informed consent explaining the procedure and potential 
harm will be obtained and a copy will be given to the subject. Then, a unique identification code 
number will be assigned to protect the subject’s identity. 
HFNC:  
The AIRVO 2 high-flow nasal cannula system (Fisher and Paykel Healthcare Limited, 
Panmure, Auckland, New Zealand) will be used. Nasal prongs sizes are chosen as per manufacturer 
recommendations. Participants will receive three levels of HFNC flow rates (30, 45, and 60 L/min) 
through nasal prongs. If a small-size nasal prong is used, the participant will receive 30, 45, and 
50 L/min flow rates instead of 30, 45, and 60 L/min, as manufacturer recommendations state the 
maximum liter flow for a small-size nasal prong is 50 L/min. Oxygen concentration will be set at 
21% and a temperature of 37 °C.  First, individuals will be placed on the sEMG monitor. Following 
the application of the sEMG, each participant will sit quietly for 10 minutes, before being attached 
to the HFNC, so a baseline swallow frequency can be established. After the baseline swallow 
frequency is established, each participant will be asked to swallow 8 boluses:  2 trials of water at 
2 volumes (5 and 10 mL) and 2 trials of applesauce at 2 volumes (5 and 10 mL). Participants will 
rest for 15 seconds after completing each swallow. This procedure will establish the participant’s 
baseline swallowing effort measurements. Once these swallows have been completed, the 
participant will be placed on the HFNC. Each participant will be placed on three different flow 
rates (30, 45, and 60 L/min or 30, 45, and 50 L/min) in random order. The random order will be 
generated by an online random number tool (https://www.randomizer.org). The study participant 
will be subjected to each flow rate for 15 minutes. During the first 10 minutes, swallow frequency 
will be recorded. After 10 minutes at the given flow, the participant will complete the 8 
aforementioned swallows. After completing all of the swallowing trials, the participant will be 
removed from the HFNC for a period of 10 minutes. This process will be repeated for all three 

flowrates for a total of 32 boluses swallowed.  
Swallowing Frequency:  
Swallowing frequency is analyzed by sEMG signals recorded on the KayPentax Digital 
Swallow Workstation™ with integrated digital swallowing signals lab (DSW™, Model 7120, New 
Jersey). A three-sensor sEMG electrode (Uni-Patch™, Disk #7500, Covidien Corporation, Tyco 
Healthcare, Wabasha, MN) will be placed on the anterior neck skin under the chin, over the 
submental muscles above the hyoid bone. Each patch will include two recording electrodes and a 
third ground electrode. Spontaneous swallowing frequency is calculated as the number of swallows 
per minute (SPM) for 10 minutes on room air and then for each HFNC intervention. Swallows will 
be counted from the visual myographic waveform produced by the DSW. 
Swallowing Effort: 
Both swallowing amplitude and timing parameters will be obtained by analyzing the 
individual graphic waveforms produced by the DSW algorithm.  Measures will be obtained for 
each of the 8 swallows, at each of the HFNC flow rates.   
Procedures Done for Research Purpose  
 The use of HFNC with three levels of flow (30, 45, and 60 L/min or 30, 45, and 50 L/min 
[for small-size nasal prongs]). 
 Swallow frequency measurement through sEMG. 
Swallowing effort measurement through sEMG – participants will swallow measured amounts of 
water and applesauce.  Presentation of the different volumes and viscosities will be done in pre-
determined random order.   

 
Application of sEMG monitor
• Patient sits quietly for 10 minutes to establish baseline swallow frequency
-Participants swallow 8 boluses to establish baseline swallow effort
-Two trials of water at two volumes (5 and 10 ml)
-Two trials fo applesauce at two volumes (5 and 10 ml)
-Participants will rest for 15 seconds after completing each swallow
Participants placed on HFNC cannula (size based on manufacturer recommendations)
HFNC flowrate applied to patient at random amounts for 15 mins per flowrate
• For each flowrate, swallow frequency will be recorded for  the first 10 minutes. 
During the last 5 minutes, the participants will complete the 8 aformentioned 
swallows (water and applesauce)
• After swallows are complete for each flowrate, the HFNC will be removed and 
participant will rest for 10 minutes
• After the rest period, the process will be repeated with the other flowrates 
(random order)

Subject Population 
Fifty healthy adult volunteers above the age of 21 will be assessed.  
Inclusion criteria: 
 
Age >21 y/o  
 
Functional cognition as determined by the participant’s ability to follow verbal directions; no 
formal cognitive test will be administered. Anyone not able to follow 1-step directions will be 
withdrawn from the study.  
 
Eat a “general/regular consistency” diet—determined by scoring a 6 or 7 on the Functional Oral 
Intake Scale (FOIS).24   
Exclusion criteria:  
 Age < 21 y/o 
 Allergy to applesauce 
 History of dysphagia or disease/condition that may cause dysphagia such as: 
- 
Achalasia 
- 
Diffuse spasm 
- 
Esophageal tumors or scar tissue 
- 
Esophageal rings 
- 
Gastroesophageal reflux disease (GERD) 
- 
Eosinophilic esophagitis 
- 
Scleroderma 
- 
Radiation therapy 
- 
Neurological disorders (multiple sclerosis, muscular dystrophy and Parkinson's 
disease) 
- 
Neurological damage (from a stroke or brain or spinal cord injury) 
- 
Pharyngeal diverticula 
 Use of medications that alter swallowing function  
- 
Benztropine mesylate (Cogentin) 
- 
Oxybutynin (Ditropan) 

- 
Propantheline (Pro-Banthine) 
- 
Tolterodine (Detrol) 
 The presence of tracheostomy tube. 
 Nasal obstruction.  
Recruitment and Consent Procedures: 
 Recruitment will be based on the inclusion and exclusion criteria.  
 Emails will be used to inform potential participants. 
 
Snowball sampling (non-probability sampling) will be utilized to recruit individuals outside of the 
Respiratory Care and Speech Language departments 
 Informed consent explaining the procedures and potential harm will be obtained from all 
individual participants in the study.  
Compensation: 
 There will be no compensation provided to participants for participation in this study. 
Risk to subject: 
 Risks include aspiration of water or applesauce when swallowing on the HFNC. 
Discomfort and dryness of mouth or nose due to the use of the high flow. Also, since the 
swallowing measurement device is applied through patch to skin, allergic reaction may 
occur. Participants will be closely monitored by the study investigators and if any signs 
of aspiration (coughing, shortness of breath), discomfort, or allergic reaction occurs, the 
session will be terminated and the participant will be withdrawn from the study.  
Special Precautions: 
 All study material will be coded to de-identify participants and a separate list will be kept 
with the participant’s ID and name.  
 
 

Confidentiality: 
 The study investigators, along with the IRB, will have access to the individual 
participant’s results. Neither names nor personal information will be recorded or included 
in the data analysis. The investigators will strictly adhere to IRB guidelines to ensure that 
participant’s confidentiality is maintained. 
Plans for Data Analysis: 
 The data collected will include swallow frequency (calculated as swallows per minute), 
peak effort amplitude (the highest amplitude of swallowing effort), and swallowing speed 
(the difference between the onset and offset of muscle contraction). Simple 1-way repeated 
measures ANOVA will be used to determine significant differences in swallowing 
frequency between oxygen flow rates (p < .05). A 4-way mixed methods repeated measures 
ANOVA (HFNC x volume x viscosity x age) will be used to determine significant 
differences in amplitude and timing (p < .05).  
 
 

 
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