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Trial registered on ANZCTR

Registration number
Ethics application status
Not yet submitted
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
A pilot study of healthy volunteers to compare the performance of standard nasal oxygen cannula at high flows with the “Optiflow” high flow nasal oxygen (HFNO) system.
Scientific title
A pilot study of healthy volunteers to compare the performance of standard nasal oxygen cannula at high flows with the “Optiflow” high flow nasal oxygen (HFNO) system.
Secondary ID [1] 294711 0
Universal Trial Number (UTN)
Trial acronym
Standard Nasal Oxygen Cannula versus High flow.
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Problem: Perioperative Oxygen delivery 307579 0
Condition category
Condition code
Anaesthesiology 306648 306648 0 0

Study type
Description of intervention(s) / exposure
The purpose of this trial is to compare traditional nasal oxygen cannula at high flows with proprietary high flow nasal oxygen (HFNO) systems.
30 healthy volunteers (who are themselves anaesthetists) will receive proprietary HFNO or oxygen via nasal cannula at max flows. A 2 lumen line will be inserted nasally to the hypopharynx to record pressure and gas concentrations..
The following parameters will be recorded:
a. Transcutaneous pO2
b. Flow at which significant discomfort is reported
c. Pharyngeal pressure (via pressure inducer in pharynx- 2 lumen catheter)
d. Pharyngeal gas concentrations / time to plateau (via gas sample in pharynx- 2 lumen catheter)
e. Live gastric ultrasound to assess insufflation
f. Sound intensity

The intervention will be 2 x 5 minute sessions.
Sessions will be separated by 10 minutes to facilitate oxygen washout.
Oxygen will be delivered either at 60L/min via Optiflow
Max flow via standard cannula (previously measured at aprox 55L/min)
In each case the concentration of oxygen is 100%. No pressure limiting device will be employed.
Intervention code [1] 301003 0
Treatment: Devices
Comparator / control treatment
The volunteers will act as their own controls.
They will be randomised to receive either proprietary HFNO or standard nasal cannula first.
All volunteers will receive both treatments.
Control group

Primary outcome [1] 305646 0
Comparing oxygen delivery via proprietary HFNO system and standard nasal cannula at high flow, measured in pO2. This will be measured via transcutaneous oximetry. Devices with this capability include the "Perimed PeriFlux System 5000 tcpO2 monitor"
Timepoint [1] 305646 0
It is anticipated that a plateau will be reached in <5mins based on prior studies
Primary outcome [2] 305647 0
Presence or absence of gastric insufflation, characterised by bubbles on gastric ultrasound.
Timepoint [2] 305647 0
This will be monitored using real time gastric ultrasound for the duration of the high flow oxygen therapy; eg 5 minutes in total.
Secondary outcome [1] 346026 0
Comfort, flows at which significant discomfort, if any, is reported.
Participants will be asked to grade the interventions as "not uncomfortable", "mildly uncomfortable", "moderately uncomfortable", "very uncomfortable" or "intolerable".
Timepoint [1] 346026 0
This questionnaire will be recorded within 5 minutes of completing each intervention.
Secondary outcome [2] 346028 0
Pharyngeal pressure. A soft plastic dual lumen catheter will be introduced into the pharynx via the nose until it is visible in the pharynx when viewed through the mouth. It will be connected to a manometer and real time pressure will be recorded throughout the interventions.
Timepoint [2] 346028 0
Continuous recording throughout interventions.
Secondary outcome [3] 346029 0
pharyngeal gas concentrations.
Oxygen and carbon dioxide will be monitored in real time using the in built gas analyser in an anaesthetic machine throughout the interventions. The gases will be sampled from the participants pharyngeal space via two lumen catheter. The second lumen of the pharyngeal catheter is connected to a manometer from which real time pressure measurements will be recorded throughout the interventions.
Timepoint [3] 346029 0
Continuos recording throughout interventions.
Secondary outcome [4] 346031 0
noise levels. measured using a sound meter, recorded in decibels, the sensor will be located aprox 50cm from the participants head, approximately the position of an attending anaesthetist.
Timepoint [4] 346031 0
Continuos recording throughout interventions.

Key inclusion criteria
Participant to be an anaesthetist. Healthy, non pregnant volunteers. No significant organ impairment of any kind. Aged 18-65. BMI 18-29 kg/m2.
Minimum age
18 Years
Maximum age
65 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
• Respiratory / airway disease.
• Coagulopathy / anticoagulation or anti-platelet therapy.
• History of severe epistaxis.
• History of diabetes mellitus.
• History of severe gastro-oesophageal reflux disease, hiatus hernia or previous gastro-oesophageal surgery.
• Pregnancy.
• Any displaced nasal injury or history of nasal congestion.
• Participants unable to give informed consent.
• No at-risk populations will be targeted for inclusion.

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Volunteers will be randomised to receive either proprietary HFNO or standard cannula via closed envelope. Participants will not be blinded to the intervention. Data will be analysed by researchers without access to the allocations.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
• Minimal statistical input will be required for this study.
• The subjective experience of discomfort will likely vary between participants; we do not know whether this data will be normally distributed; it will we scrutinised using the D’Agostino & Pearson Omnibus test and suitable parametric or non-parametric statistical tests will be used on the data. Results will be expressed accordingly.
• Continuous variables measure of FiO2, pO2 pressure and noise will likely be normally distributed around a small range between participants. Suitable tests will be done to confer a difference or not between the methods of oxygen delivery and also between the two genders.
• Binary data, eg gastric insufflation yes/no will be subject to the Fisher’s exact test given the low number of participants involved.

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 10782 0
Fiona Stanley Hospital - Murdoch
Recruitment hospital [2] 10783 0
Fremantle Hospital and Health Service - Fremantle
Recruitment postcode(s) [1] 22520 0
6150 - Murdoch
Recruitment postcode(s) [2] 22521 0
6160 - Fremantle

Funding & Sponsors
Funding source category [1] 299316 0
Name [1] 299316 0
Fiona Stanley Hospital
Address [1] 299316 0
11 Robin Warren Dr
Country [1] 299316 0
Primary sponsor type
Fiona Stanley Hospital
11 Robin Warren Dr
Secondary sponsor category [1] 298584 0
Name [1] 298584 0
Address [1] 298584 0
Country [1] 298584 0
Other collaborator category [1] 280083 0
Name [1] 280083 0
National Maternity Hospital
Address [1] 280083 0
Holles Street,
Dublin 2,
Country [1] 280083 0

Ethics approval
Ethics application status
Not yet submitted
Ethics committee name [1] 300224 0
South Metropolitan Health Service Human Research Ethics Committee [EC00265]
Ethics committee address [1] 300224 0
11 Robin Warren Dr,
Murdoch 6150
Ethics committee country [1] 300224 0
Date submitted for ethics approval [1] 300224 0
Approval date [1] 300224 0
Ethics approval number [1] 300224 0

Brief summary
Background: Oxygen therapy has been a cornerstone of medical therapy since 1890. Current nasal oxygen cannula have been in use since 1949. Low flow oxygen via traditional nasal oxygen cannula (up to 15L/min) have been shown to modestly prolong time to desaturation when used while inducing general anaesthesia. High flow (± 60L/min) humidified nasal oxygen (HFNO) has been show to dramatically prolong time to desaturation. Apnoeic oxygenation has become well established clinical practice in recent years. Furthermore a volunteer study showed similar oxygen delivery when HFNO is compared to face mask ventilation.

It is not known if similar oxygen delivery can be achieved using traditional cannula at high flows. Also the maximum flows achievable via nasal cannula from commonly available oxygen outlets has not been published. The first part of our study will be to establish this information using a gas flow analyser. Early work by our group has shown typical flows of ±55L/min.

Our objective is to test the question of whether standard cannula supplying oxygen at high flows show comparable oxygen delivery to the well-researched proprietary HFNO systems. In addition to this we are interested to ascertain whether either therapy contributes significantly to gastric insufflation. Multiple previous case reports have been published of nasopharyngeal catheters resulting in gastric distension and rupture. No published data is yet available to demonstrate whether nasal cannulae, at high flow can also contribute to this potential complication.

Our trial plan is to do a study of 30 healthy volunteers, comparing the oxygen delivery (via transcutaneous oxygen measurement) of HFNO via proprietary (humidified/ warmed) system (Optiflow, Fisher and Paykal, NZ) and comparing it to HFNO via traditional nasal cannula at high flow (±55L/min) and low flow (15L/min). Further parameters recorded and compared include; pharyngeal pressure generated, pharyngeal oxygen concentrations obtained, noise levels and participant comfort. A further key aspect of the study will be to examine whether gastric insufflation, a theoretical consequence of using a HFNO technique, does indeed result. For this, real time gastric ultrasound will be used.

Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 82970 0
Dr Mark Johnson
Address 82970 0
Dept. of anaesthetics,
Fiona Stanley Hospital,
11 Robin Warren Dr
Country 82970 0
Phone 82970 0
Fax 82970 0
Email 82970 0
Contact person for public queries
Name 82971 0
Dr Mark Johnson
Address 82971 0
Dept. of anaesthetics,
11 Robin Warren Dr
Fiona Stanley Hospital,
Country 82971 0
Phone 82971 0
+618 6152 2222
Fax 82971 0
Email 82971 0
Contact person for scientific queries
Name 82972 0
Dr Mark Johnson
Address 82972 0
Dept. of anaesthetics,
11 Robin Warren Dr
Fiona Stanley Hospital,
Country 82972 0
Phone 82972 0
+618 6152 2222
Fax 82972 0
Email 82972 0

No information has been provided regarding IPD availability
Summary results
No Results