Examining the Effects of Nasal High Flow Oxygen Therapy Compared to Non-invasive Ventilation in Health Volunteers
Healthy Volunteers
What this study involves
The registry does not currently label this study as recruiting. Ask about its status before planning a screening visit.
- Study type
- Observational
- Phase
- Not applicable / not listed
- Age range
- 18 years - Not specified
- Sex eligible
- All sexes
- Healthy volunteers
- Accepted
- Participants
- 20 Estimated
These are starting points, not an eligibility decision. The research team must review the full requirements.
About the research
Respiratory failure is characterized by low levels of oxygen and high levels of carbon dioxide in the blood which causes difficulty breathing. The management of patients with respiratory failure aims at improving oxygenation and changing the effort required to breathe. Mechanical ventilation is a life-saving treatment but may be associated with a high mortality rate, prolonged stay in the intensive care unit (ICU), and infection. Oxygenation techniques to avoid mechanical ventilation include standard oxygen therapy, continuous positive pressure (CPAP), and high-flow nasal cannula oxygen therapy (HFNC). CPAP consists of delivering oxygen through a mask. As compared to standard oxygen therapy, CPAP can promote lung recruitment leading to improved oxygenation and the effect in work of breathing in patients with respiratory failure. Conversely, high-flow nasal cannula oxygen therapy (HFNC) delivers oxygen through nasal prongs. Oxygen is heated and humidified and can be delivered at different flows (from 10 - 60 L/min). As compared to standard oxygen therapy, HFNC can promote some lung recruitment leading to mofiy oxygenation and work of breathing. Therefore, the present study will have 2 phases:
Phase 1:Comparison of the physiological effects of different flows of HFNC to CPAP in healthy volunteers. The investigators hypothesized that the physiological effects of HFNC in the nasopharynx are comparable to that of CPAP at 4 cm H2O.
Phase 2: Comparison of the physiological effects of different nasal interfaces of HFNC (Standard cannula vs. Asymmetrical cannula vs. Single-nostril adapted cannula) in healthy volunteers. The investigators hypothesized that the physiological effects of HFNC in the nasopharynx are comparable to that of CPAP at 4 cm H2O. It was hypothesized that asymmetrical which is the cannula that has a higher cross-sectional area generates higher nasal pharyngeal pressure.
Who may be able to participate?
The list below is the sponsor’s full registry wording. It can include conditions, prior treatment, test results and other requirements. A match in search does not mean you qualify.
Inclusion Criteria:
- Healthy volunteers ≥ 18 y-o,
- No evidence of acute or chronic cardiopulmonary disease
Exclusion Criteria:
- Active epistaxis, sinus problem, nasal trauma, or deviated septum that would preclude the nasopharyngeal catheter insertion,
- Pregnancy, clinical evidence of respiratory illness, history of respiratory disease, body mass of over 50 kg/m2, ribcage malformation,
- Cardiac pace maker or implantable cardioverter-defibrillator according to EIT manufacturer,
- Allergy to topical lidocaine,
- Claustrophobia that would preclude the use of CPAP or HFNC.
Study population
Healthy volunteers responding to advertisement posted through the St. Michael's Hospital Communications board.
Understand screeningTreatment, groups and participation
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- Assignment
- Not reported
- Masking
- Not reported
Phase 1 and 2 OTHER
First, participant will be randomized to a protocol during our study. Participant will breathe normally at different flows of HFNC (20, 40 or 60 L/min) with their mouth open and mouth closed at each flow. They will breathe normally with CPAP at a positive pressure of 4 cm H2O. A lubricated catheter is inserted above the glottis through the nostril to measure ventilatory parameters. EIT is applied to measure inflation of the lung using electromagnetic waves that are not perceptible and are harmless. An ultrasound is done to measure the thickening of your diaphragm and of your abdominal muscles during inspiration and expiration and vocal cords position with and without HFNC (single measurement - around 3 min).During the second step, second catheter is inserted through the nostril to measure esophageal pressure. They will breathe for one additional minute during the closed mouth portions of the experiment while watching the esophageal pressure to ensure steady effort.
Phase 3 OTHER
In the 3rd phase, according to randomization, volunteers will be masked with either RT041, RT043 or ONIV117 first, followed by the second mask then third mask, also randomize mouth position set to open or closed. The fitting of the masks will be determined based on the manufacturer guidelines and healthy volunteer tolerance. The mask will be adjusted to minimize leaks. At each step, EIT measurements will be recorded at regular breathing over a 10-minute period with an 8-minute washout between devices and 5-minute washout period between mouth positions. The transcutaneous CO2 will be continuously monitored from the earlobe throughout the protocol.
What researchers are measuring
Outcome measures describe what is being studied. They are not proof that a treatment works.
Primary measures
End expiratory nasopharyngeal pressure (NP)
Time frame: 5 minutes
The primary endpoint is to compare the end expiratory nasopharyngeal pressure (NP) under 60 L/min of high flow nasal cannula (HFNC) to continuous positive airway pressure (CPAP 4 cmH2O).This will be assessed using a nasopharyngeal catheter.
End expiratory nasopharyngeal pressure (NP)
Time frame: 5min
The primary endpoint is to compare the end expiratory nasopharyngeal pressure (NP) of high flow nasal cannula (HFNC) among the 3 different nasal cannulas (Symmetrical, Asymmetrical, Single-nostril adapted).
Secondary measures
Change in physiologic variables of airway pressure at different flows of HFNC (20, 40, and 60 L/min) and CPAP (4 cmH20). In the phase#2; HFNC 2, and 50 L/min.
Time frame: 5 minutes
One of the secondary endpoints is to compare variables of airway pressure at different flows of HFNC to CPAP. The investigators will measure the end expiratory NP, mean NP, mean peak inspiratory pressure, mean peak expiratory pressure, delta inspiratory pressure and delta expiratory pressure.
Each of these variables will be measured for 1 minute using a nasopharyngeal catheter. Furthermore, at each flow of HFNC, the investigators will ask the patient to breathe with their mouth open and mouth closed.
Change in end-expiratory lung impedance
Time frame: 5 minnutes
The other secondary endpoint is to compare the change in ventilation distribution and end-expiratory lung impedance at different flows of HFNC and CPAP (Different nasal cannulas in the 2nd phase). These variables will be measured using electrical impedance tomography (EIT) by placing a band around the chest of each participant.
Dead-space washout in the upper airways
Time frame: 5 minutes
Assess whether the transcutaneous CO2 is modified by HFNC, while comparing 3 different nasal cannulas (Symmetrical, Asymmetrical, Single-nostril adapted).
Review the complete result tables and limitations in the official record.
Open official results ↗Research locations (1)
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1 locations
St. Michael's HospitalToronto, Ontario, CanadaStatus unknown
Study team and timeline
- Lead sponsor
- Unity Health Toronto
- Study start
- Apr 10, 2019 Actual
- Primary completion
- Mar 30, 2024 Actual
- Study completion
- Oct 1, 2027 Estimated
- First posted
- Apr 4, 2019 Actual
- Last updated
- Nov 10, 2026 Actual
Official study contacts
No central contact is listed. Check the locations and the official record.
Official study title
Comparative Study of the Physiological Effects of High Flow Nasal Cannula and Non-invasive Ventilation in Healthy Volunteers
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Source: ClinicalTrials.gov API v2. Information is submitted by sponsors and investigators. NLM does not approve the safety or science of all listed studies. Registry disclaimer.
Retrieved: Nov 11, 2026 · Last registry update: Nov 10, 2026