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Trial registered on ANZCTR


Registration number
ACTRN12618000141246
Ethics application status
Approved
Date submitted
23/01/2018
Date registered
31/01/2018
Date last updated
14/05/2019
Date data sharing statement initially provided
14/05/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
The respiratory effect of high-flow nasal oxygen in spontaneously breathing or apnoeic adults during general anaesthesia: a randomised controlled trial.
Scientific title
The respiratory effect of high-flow nasal oxygen in spontaneously breathing or apnoeic adults during general anaesthesia: a randomised controlled trial.
Secondary ID [1] 293858 0
None
Universal Trial Number (UTN)
U1111-1208-3507
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
laryngeal pathology 306321 0
Condition category
Condition code
Anaesthesiology 305401 305401 0 0
Anaesthetics
Surgery 305404 305404 0 0
Surgical techniques

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
High-flow nasal oxygen during apnoea. Preoxygenation using the HFNO at a concentration of 100% will commence at a flow rate of 30L/min for 3 minutes then increase to 50L/min for 3 minutes and then increase to 70L/min for 3 minutes prior to the induction of anaesthesia. The oxygen concentration and flow rate will remain at 100% and 70L/min respectively throughout the rest of the procedure. Intravenous induction of general anaesthesia using target-controlled infusions of remifentanil and propofol will be titrated to haemodynamics and to maintain a BIS between 40-50. A 0.5mg/kg bolus of rocuronium will be administered when the patient loses consciousness. Jaw thrust will be used to maintain upper airway patency during the period of apnoea until the surgeon places a suspension laryngoscope. Direct and indirect laryngoscopy using a CMAC videolaryngoscope will be performed by the anaesthetist to assess the airway grade. The surgeon will then place a suspension laryngoscope and perform a microlaryngeal surgical procedure.. At the conclusion of the surgical procedure, a supraglottic airway will be placed, and positive pressure ventilation commenced. The patient will then have the rocuronium reversed with a 2mg/kg bolus of sugammadex, the propofol infusion will be ceased and the patient will be transitioned to spontaneous ventilation and allowed to emerge from general anaesthesia. The patient will be recovered in PACU and discharged to the ward with conventional post-operative orders including analgesia. The anaesthesia will be provided by consultant anaesthetists experienced with microlaryngeal surgery and the use of HFNO or trainee anaesthetists under their direction. The surgery will be provided by consultant surgeons experienced with microlaryngeal surgery and the use of HFNO or trainee surgeons under their direction. The intervention will occur once in operating theatre for an expected duration of 30minutes of general anaesthesia for each study participant.
Intervention code [1] 300121 0
Treatment: Devices
Comparator / control treatment
High-flow nasal oxygen during spontaneous ventilation using intravenous anaesthesia. Preoxygenation using the HFNO at a concentration of 100% will commence at a flow rate of 30L/min for 3 minutes then increase to 50L/min for 3 minutes and then increase to 70L/min for 3 minutes prior to the induction of anaesthesia. The oxygen concentration and flow rate will remain at 100% and 70L/min respectively throughout the rest of the procedure. Intravenous induction of general anaesthesia using target-controlled infusions of propofol will be titrated to maintain spontaneous respiration. Jaw thrust will be used to maintain upper airway patency during the period of apnoea until the surgeon places a suspension laryngoscope. Direct and indirect laryngoscopy using a CMAC videolaryngoscope will be performed by the anaesthetist to assess the airway grade and apply local anaesthesia spray to the larynx. The surgeon will then place a suspension laryngoscope and perform a microlaryngeal surgical procedure. At the conclusion of the surgical procedure, a supraglottic airway will be placed, the propofol infusion will be ceased and the participant will be allowed to emerge from general anaesthesia. The patient will be recovered in PACU and discharged to the ward with conventional post-operative orders including analgesia. The anaesthesia will be provided by consultant anaesthetists experienced with microlaryngeal surgery and the use of HFNO or trainee anaesthetists under their direction. The surgery will be provided by consultant surgeons experienced with microlaryngeal surgery and the use of HFNO or trainee surgeons under their direction. The intervention will occur once in operating theatre for an expected duration of 30minutes of general anaesthesia for each study participant.
Control group
Active

Outcomes
Primary outcome [1] 304542 0
The difference between the arterial partial pressure of carbon dioxide measured by direct arterial sampling and arterial blood gas analysis. This will assess the efficacy of high-flow nasal oxygen to assist ventilation. Raised carbon dioxide is a potential limiting factor during apnoeic techniques especially associated with prolonged periods beyond 30minutes of general anaesthesia. The primary outcome will provide important information about the safety of high-flow nasal oxygen related to ventilation and potentially raised carbon dioxide levels.
Timepoint [1] 304542 0
Measured at 30minutes of spontaneous ventilation time during general anaesthesia in the spontaneously breathing group and 30minutes of apnoea time during general anaesthesia in the apnoeic group.
Secondary outcome [1] 342332 0
Serial sampling of the arterial partial pressure of carbon dioxide measured by direct arterial sampling and arterial blood gas analysis at 3minute intervals during the pre oxygenation and 5 minute intervals during the 30minute sampling period of general anaesthesia to plot the trajectory of changes in carbon dioxide that occurs in both groups.
Timepoint [1] 342332 0
Serial measures taken at 3minute intervals during the pre oxygenation and 5 minute intervals during the 30minute sampling period of general anaesthesia.
Secondary outcome [2] 342345 0
The difference between the arterial partial pressure of oxygen measured by direct arterial sampling and arterial blood gas analysis.
Timepoint [2] 342345 0
Measured at 30minutes of spontaneous ventilation time during general anaesthesia in the spontaneously breathing group and 30minutes of apnoea time during general anaesthesia in the apnoeic group.
Secondary outcome [3] 342346 0
Serial sampling of the arterial partial pressure of oxygen measured by direct arterial sampling and arterial blood gas analysis at 3minute intervals during the pre oxygenation and 5 minute intervals during the 30minute sampling period of general anaesthesia to plot the trajectory of changes in oxygen that occurs in both groups.
Timepoint [3] 342346 0
Serial measures taken at 3minute intervals during the pre oxygenation and 5 minute intervals during the 30minute sampling period of general anaesthesia.
Secondary outcome [4] 342347 0
Correlation between the arterial partial pressure of carbon dioxide and other forms of carbon dioxide measurement (e.g. transcutaneous or end-tidal). This will be assessed by comparing the difference between the arterial partial pressure of carbon dioxide and end-tidal (or transcutaneous) carbon dioxide measured at the same sampling time points.
Timepoint [4] 342347 0
During or immediately after the use of HFNO.
Secondary outcome [5] 342350 0
The difference between surgical conditions subjectively assessed by the surgeon using a subjective scale (good, average, poor, impossible).
Timepoint [5] 342350 0
Measured at 5 minute intervals during the surgical procedure.
Secondary outcome [6] 342400 0
Respiratory rate measured by capnography or manually.
Timepoint [6] 342400 0
Measured at the baseline, at 1 minute intervals during pre oxygenation and at 5minute intervals during general anaesthesia.
Secondary outcome [7] 342401 0
Heart rate measured with non-invasive automated sphygmomanometry and/or invasive (intra-arterial) blood pressure monitoring using an arterial line.
Timepoint [7] 342401 0
Measured at the baseline and at 3 minute intervals during pre oxygenation and 5 minute intervals during general anaesthesia for non-invasive monitor and continuously over the same duration for the invasive monitor.
Secondary outcome [8] 342404 0
Heart rate measured with electrocardiography.
Timepoint [8] 342404 0
Measured at the baseline and continuously during pre oxygenation and general anaesthesia.

Eligibility
Key inclusion criteria
Ear, Nose and Throat surgical patients requiring microlaryngoscopy
Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Severe obstructive airway pathology making potential intubation difficult.
A requirement for laser.
Severe pre-existing respiratory disease.
A requirement for a suspension subglottiscope.
Pre-operative criteria suggestive of a high risk of aspiration.
Women who are pregnant and the human fetus
Children and young people
People highly dependent on medical care who may be unable to give consent
People with a cognitive impairment, intellectual disability or mental illness
People in dependent or unequal relationships
People who may be involved in illegal activities
People in other countries
Aboriginal and Torres Strait Islander peoples

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation concealment by sealed opaque envelopes.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Safety/efficacy
Statistical methods / analysis
We have selected a sample size of 10 patients in both groups based on a power calculation using previously published end-tidal carbon dioxide data for both apnoeic and spontaneously respiration general anaesthetic techniques using high-flow nasal oxygen. We consulted a biostatistician to calculate our sample size: a sample size of 7 in each group will have 95% power to detect a difference in means of 20 mmHg (which is clinically significant) at 30minutes assuming that the common standard deviation is 10.5 mmHg using a two group t-test with a 0.05 one-sided significance level. To be conservative, we have selected a sample size of 10 in each group.

A two group t-test will be used to compare the means of the arterial carbon dioxide of both groups. Analysis will include both intention to treat and per protocol. We have consulted with a biostatistician who will perform the statistical analysis of the study data.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
30/07/2018
Actual
1/08/2018
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
20
Accrual to date
1
Final
Recruitment in Australia
Recruitment state(s)
QLD
Recruitment hospital [1] 9856 0
Princess Alexandra Hospital - Woolloongabba
Recruitment postcode(s) [1] 18641 0
4102 - Woolloongabba

Funding & Sponsors
Funding source category [1] 298479 0
Hospital
Name [1] 298479 0
Princess Alexandra Research Foundation
Country [1] 298479 0
Australia
Primary sponsor type
Individual
Name
Dr Anton Booth
Address
Princess Alexandra Hospital
Department of Anaesthesia
199 Ipswich Road Woolloongabba Qld 4102
Country
Australia
Secondary sponsor category [1] 297618 0
None
Name [1] 297618 0
Address [1] 297618 0
Country [1] 297618 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 299466 0
Metro South Human Research Ethics Committee
Ethics committee address [1] 299466 0
Metro South Hospital and Health Service
Level 7 TRI, 37 Kent Street WOOLLOONGABBA QLD 4102
Ethics committee country [1] 299466 0
Australia
Date submitted for ethics approval [1] 299466 0
Approval date [1] 299466 0
14/12/2017
Ethics approval number [1] 299466 0
HREC/17/QPAH/782

Summary
Brief summary
The aim of this study is to define the effect that high-flow nasal oxygen has on ventilation and oxygenation in both apnoeic and spontaneously breathing participants during a 30minute period of general anaesthesia.

The use of high-flow nasal oxygen is gaining popularity in anaesthesia due to its benefits on oxygenation and ventilation. The precise effect that high-flow nasal oxygen has on oxygen and carbon dioxide levels during general anaesthesia during spontaneous respiration or apnoea is yet to be defined. Therefore it is not clear which technique may be more suitable for particular patient subgroups. No previous studies have directly compared apnoeic and spontaneously breathing techniques using high-flow nasal oxygen during general anaesthesia.

We hypothesise that carbon dioxide levels will be different between spontaneously breathing and apnoeic patients while using high-flow nasal oxygen during a 30minute period of general anaesthesia.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 80498 0
Dr Anton Booth
Address 80498 0
Princess Alexandra Hospital
199 Ipswich Road Woolloongabba Qld 4102
Country 80498 0
Australia
Phone 80498 0
+61731762111
Fax 80498 0
Email 80498 0
anton.booth@uq.edu.au
Contact person for public queries
Name 80499 0
Dr Anton Booth
Address 80499 0
Princess Alexandra Hospital
199 Ipswich Road Woolloongabba Qld 4102
Country 80499 0
Australia
Phone 80499 0
+61731762111
Fax 80499 0
Email 80499 0
anton.booth@uq.edu.au
Contact person for scientific queries
Name 80500 0
Dr Anton Booth
Address 80500 0
Princess Alexandra Hospital
199 Ipswich Road Woolloongabba Qld 4102
Country 80500 0
Australia
Phone 80500 0
+61731762111
Fax 80500 0
Email 80500 0
anton.booth@uq.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
Ethics approval for IPD was not sought


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.