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Trial registered on ANZCTR


Registration number
ACTRN12618000445279p
Ethics application status
Submitted, not yet approved
Date submitted
16/03/2018
Date registered
28/03/2018
Date last updated
28/03/2018
Type of registration
Prospectively registered

Titles & IDs
Public title
Use of high flow nasal oxygen in bariatric surgery: a randomised controlled trial
Scientific title
The efficacy of Transnasal humidified Rapid-insufflation ventilator exchange (THRIVE) in obese adults: a randomised controlled trial.
Secondary ID [1] 294364 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obesity 307091 0
Airway management 307092 0
Apnoeic oxygenation 307093 0
Condition category
Condition code
Anaesthesiology 306204 306204 0 0
Anaesthetics
Respiratory 306205 306205 0 0
Other respiratory disorders / diseases
Diet and Nutrition 306256 306256 0 0
Obesity

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
After manually oxygenating the patient to an end-tidal oxygen concentration (FEO2) of 0.9 via bag-mask-ventilation, oxygen will be administered via the Optiflow THRIVE device, at a flow rate of 50-70LPM as tolerated, humidified using the Fisher and Paykel 850 humidifier, to a humidity of 70% relative humidity. The oxygen concentration delivered from the device will be 100%, but the actual inspired oxygen concentration will vary with the degree of air entrainment.

Pre-operatively an arterial line will be inserted for baseline and post-apnoea arterial blood gas analysis and blood pressure measurement. Arterial line insertion and invasive blood pressure monitoring is current practice in our institution in the management of an obese patient due to the lack of reliability of non-invasive blood pressure measurements in this population. Additionally, the use of an arterial line allows for repeated blood samples to be taken without exposing the patient to repeated skin puncture. Induction of anaesthesia will be conducted with alfentanil or fentanyl, propofol and rocuronium 1mg/kg of calculated lean body weight. Maintenance of anaesthesia during the period of data collection will be via intravenous propofol infusion. The patient will be ventilated with bag mask ventilation and the treating anaesthetist will perform gentle laryngoscopy with a CMAC video laryngoscope when the patient is pharmacologically paralysed. Laryngoscopy will take approximately 60 seconds. If the patient is judged to be an easy bag-mask ventilation and Cormack-Lehane laryngoscopy grade I or II, the laryngoscope will be removed and the patient will be bag-mask ventilated to an end-tidal oxygen of 90%. Once this target it reached, Optiflow THRIVE will be applied to the patient, an adequately sized an oropharyngeal airway inserted and airway manoeuvres (chin lift, head tilt, jaw thrust) performed to ensure airway patency. The patient will remain anaesthetised and apnoeic until an SpO2 of 95% or a time of six minutes is reached. At this point Optiflow THRIVE will be removed and the patient manually bag mask ventilated until SpO2 of 98% is achieved, and the patient will be intubated. During the period of apnoeic oxygenation, anaesthesia will be maintained with a propofol infusion.

The intervention will only be performed once during the trial, for a maximum time period of 6 minutes. The procedure will be performed by a specialist anaesthetist with at least 5 years of anaesthetic experience, or by an anaesthetic trainee with a consultant anaesthetist present. The trial will occur at a tertiary hospital. The trial will be performed under direct supervision by the research practitioner in order to ensure that the intervention and control groups are being adhered to.
Intervention code [1] 300669 0
Treatment: Devices
Comparator / control treatment
After manually oxygenating the patient to an end-tidal oxygen concentration (FEO2) of 0.9 via bag-mask-ventilation, oxygen will be administered at 4L/min via nasal cannulae while the patient is anaesthetised, paralysed, apnoeic with an oropharyngeal airway inserted and airway manoeuvres (chin lift, head tilt, jaw thrust) performed to ensure airway patency.
Control group
Active

Outcomes
Primary outcome [1] 305211 0
Time to SpO2 95% during apnoeic oxygenation - time measured by research nurse present in theatre, from application of intervention/control/commencement of apnoea to SpO2 95%.
Timepoint [1] 305211 0
Within six minutes of application of intervention or control
Primary outcome [2] 305212 0
Rate of rise of PaCO2 - PaCO2 measured using arterial blood sampling after ETO2 0.9 reached and then re-measured when SpO2 is less than 95% or 6 minutes, whichever occurs first. The difference in PaCO2 is then divided by the duration of apnoea to give a rate of rise of PaCO2 mmHg/min.
Timepoint [2] 305212 0
From immediately before application of intervention or control until immediately after intubation.
Primary outcome [3] 305213 0
Rate of rise of transcutaneous CO2 - TcCO2 measured using transcutanoues CO2 monitor after ETO2 0.9 reached and then re-measured when SpO2 is less than 95% or 6 minutes, whichever occurs first. The difference in TcCO2 is then divided by the duration of apnoea to give a rate of rise of TcCO2 mmHg/min.
Timepoint [3] 305213 0
From immediately before application of intervention or control until immediately after intubation.
Secondary outcome [1] 344519 0
Peak end-tidal CO2 after recommencement of ventilation - peak EtCO2 using capnograph on anaesthetic machine within the first 5 breaths after recommencement of ventilation.
Timepoint [1] 344519 0
Within the first five breaths after intubation
Secondary outcome [2] 344520 0
Any complications occurring during the procedure - airway difficulty, aspiration, prolonged hypoxia, arrhythmias, gastric insufflation etc - recorded by research nurse after study period.
Timepoint [2] 344520 0
during the entire procedure

Eligibility
Key inclusion criteria
- Patients aged >18 years
- BMI >35 kg/m2
- Scheduled for elective bariatric surgery
- Written informed consent by the patient
Minimum age
18 Years
Maximum age
No limit
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
- ASA physical status greater than or equal to 4
- Severe respiratory pathology
- Pulmonary hypertension
- Cormack-Lehane Laryngoscopy grade equal to 3 at the time of intraoperative laryngoscopy
- Difficulty with bag-mask-ventilation after induction of anaesthesia
- Pregnant patients
- Inability to obtain written informed consent

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)
Sequentially numbered, opaque sealed envelopes (SNOSE)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Block randomisation via SNOSE
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
Sample size was calculated for a comparison of means of 2 independent groups. A recent study investigating apneic oxygenation by nasal prongs reported improvements in mean time to desaturation <95% of approximately 90 seconds, with a standard deviation up to 80 seconds. The primary outcome will be analysed using Kaplan-Meier survival curves, and log-rank tests will be applied.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
QLD
Recruitment hospital [1] 10405 0
Royal Brisbane & Womens Hospital - Herston
Recruitment postcode(s) [1] 22090 0
4029 - Herston

Funding & Sponsors
Funding source category [1] 299007 0
Hospital
Name [1] 299007 0
Royal Brisbane and Women's Hospital
Address [1] 299007 0
Bowen Bridge Rd & Butterfield St, Herston QLD 4029
Country [1] 299007 0
Australia
Primary sponsor type
Hospital
Name
Royal Brisbane and Women's Hospital
Address
Bowen Bridge Rd & Butterfield St, Herston QLD 4029
Country
Australia
Secondary sponsor category [1] 298232 0
None
Name [1] 298232 0
Address [1] 298232 0
Country [1] 298232 0

Ethics approval
Ethics application status
Submitted, not yet approved
Ethics committee name [1] 299935 0
The Prince Charles Hospital HREC
Ethics committee address [1] 299935 0
Rode Road
Chermside Qld 4032
Ethics committee country [1] 299935 0
Australia
Date submitted for ethics approval [1] 299935 0
11/01/2018
Approval date [1] 299935 0
Ethics approval number [1] 299935 0

Summary
Brief summary
During general anaesthesia, obese patients are at risk of oxygen levels in the blood rapidly falling when not breathing. This rapid reduction is due to the combination of reduced chest wall and diaphragmatic tone, the increased incidence of lung collapse, and secretion retention. Administering oxygen before general anaesthesia is less effective than in patients with a normal weight and obese patients pose more difficulties with airway management.

Transnasal humidified Rapid-insufflation ventilator exchange (THRIVE) has recently gained popularity within anaesthetic practice due to the respiratory safety benefits it provides in patients who are not breathing. THRIVE increases the time in which patients can be not breathing before oxygen levels in the blood begin to fall.

The aim of this study is to identify the safety benefits of high-flow nasal oxygen deliver (Transnasal humidified Rapid-insufflation ventilator exchange (THRIVE)) in obese patients undergoing elective bariatric surgery. It may potentially increase the time to hypoxia and increase carbon dioxide elimination in obese patients who are not breathing, who are at higher risk of lung complications.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 82038 0
Dr Louis Guy
Address 82038 0
Department of Anaesthesia and Perioperative Medicine
Royal Brisbane and Women's Hospital
Bowen Bridge Rd & Butterfield St, Herston QLD 4029
Country 82038 0
Australia
Phone 82038 0
+61 7 3636 8111
Fax 82038 0
Email 82038 0
louisfguy@gmail.com
Contact person for public queries
Name 82039 0
Dr Louis Guy
Address 82039 0
Department of Anaesthesia and Perioperative Medicine
Royal Brisbane and Women's Hospital
Bowen Bridge Rd & Butterfield St, Herston QLD 4029
Country 82039 0
Australia
Phone 82039 0
+61 7 3636 8111
Fax 82039 0
Email 82039 0
louisfguy@gmail.com
Contact person for scientific queries
Name 82040 0
Dr Louis Guy
Address 82040 0
Department of Anaesthesia and Perioperative Medicine
Royal Brisbane and Women's Hospital
Bowen Bridge Rd & Butterfield St, Herston QLD 4029
Country 82040 0
Australia
Phone 82040 0
+61 7 3636 8111
Fax 82040 0
Email 82040 0
louisfguy@gmail.com

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