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Trial registered on ANZCTR


Registration number
ACTRN12616000531415
Ethics application status
Approved
Date submitted
20/04/2016
Date registered
26/04/2016
Date last updated
20/07/2018
Type of registration
Prospectively registered

Titles & IDs
Public title
High flow humidified nasal oxygenation in pregnant women
Scientific title
Efficacy of high flow humidified nasal oxygenation in healthy pregnant women and in women undergoing caesarean section under general anaesthesia
Secondary ID [1] 289052 0
None
Universal Trial Number (UTN)
U1111-1182-1418
Trial acronym
The HINOP Study
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Pregnancy 298484 0
Oxygenation 298485 0
Condition category
Condition code
Anaesthesiology 298574 298574 0 0
Anaesthetics
Reproductive Health and Childbirth 298578 298578 0 0
Childbirth and postnatal care

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
In this prospective study we aim to recruit two groups of women. Each woman will be placed on a hospital bed in an optimally ramped position and with a right lateral pelvic wedge to minimise aortocaval compression. Baseline vital signs will be measured. Whilst the woman is breathing room air (FiO2 21%) a tightly fitting face mask will be applied by a trained investigator (anaesthetist, anaesthetic registrar, medical student, or nurse) and a good seal and ideal fitting will be determined by observing the capnography trace. The face mask will then be removed. High flow humidified nasal cannulae (Optiflow (Trademark)) will then be inserted into the woman’s nostrils by the trained investigator (anaesthetist, anaesthetic registrar, trained medical student, or nurse). Humidification will be set at 44 mg/l and oxygen concentration will be 100%. The oxygen flow will be commenced (first 30 seconds at 30 l.min-1, then next 150 seconds at 50 l.min-1). Each woman will be instructed to take deep breaths. At the end of three minutes the woman will be asked to hold her breath in inspiration while the nasal cannulae are quickly removed and the tightly fitting face mask (connected to 6 l.min-1 air FiO2 100%) will be applied. The woman will then be asked to exhale normally and breathe normally. The second group of women will be those who are undergoing general anaesthesia for caesarean section. Each woman will be placed on a hospital bed in an optimally ramped position and with a right lateral pelvic wedge to minimise aortocaval compression. Baseline vital signs will be measured. A tightly fitting face mask (connected to at least 6 l.min-1 oxygen (at the discretion of the treating anaesthetist) FiO2 100%) will be applied by the anaesthetist or anaesthetic registrar and a good seal obtained (indicated by capnography trace). Once the woman’s FetO2 reaches 90% or at the discretion of the anaesthetist/anaesthetic registrar, general anaesthesia will be induced with cricoid pressure applied. The face mask will then be removed. High flow humidified nasal cannulae (Optiflow (trademark)) will then be inserted into the woman’s nostrils by the trained investigator (anaesthetist, anaesthetic registrar, medical student, or nurse). Humidification will be set at 44 mg/l and oxygen concentration will be 100%. The oxygen flow will be commenced at 70 l.min-1. Chin lift and jaw thrust will be performed. At the discretion of the treatment anaesthetist once muscle relaxation deemed to have taken effect tracheal intubation will be attempted and oxygenation and ventilation will occur once successful. (the Apnoeic oxygenation group). After successful intubation of the trachea has been achieved nasal humidified oxygenation will cease and the nasal cannulae will be removed.
Intervention code [1] 294539 0
Prevention
Intervention code [2] 294546 0
Treatment: Other
Comparator / control treatment
The comparator group is the Pre-oxygenation group. Each woman will be placed on a hospital bed in an optimally ramped position and with a right lateral pelvic wedge to minimise aortocaval compression. Baseline vital signs will be measured. Whilst the woman is breathing room air (FiO2 21%) a tightly fitting face mask will be applied trained investigator (anaesthetist, anaesthetic registrar, medical student, or nurse) and a good seal and ideal fitting will be determined by observing the capnography trace. The face mask will then be removed. High flow humidified nasal cannulae (Optiflow™) will then be inserted into the woman’s nostrils by the trained investigator (anaesthetist, anaesthetic registrar, medical student, or nurse). Humidification will be set at 44 mg/l and oxygen concentration will be 100%. The oxygen flow will be commenced (first 30 seconds at 30 l.min-1, then next 150 seconds at 50 l.min-1). Each woman will be instructed to take deep breaths. At the end of three minutes the woman will be asked to hold her breath in inspiration while the nasal cannulae are quickly removed and the tightly fitting face mask (connected to 6 l.min-1 air FiO2 21%) will be applied. The woman will then be asked to exhale normally and breathe normally and the peak FetO2 and time to achieve FetO2 of 21% will be recorded.
Control group
Active

Outcomes
Primary outcome [1] 298064 0
Pre-oxygenation group - End-tidal oxygen fraction measured by the end tidal gas analyser on the anaesthetic machine
Timepoint [1] 298064 0
After three minutes of pre-oxygenation with high flow humidified nasal oxygenation.
Primary outcome [2] 298066 0
Apnoeic oxygenation group - Lowest oxygen saturation level measured by the pulse oximeter
Timepoint [2] 298066 0
Pulse oximetry (oxygen saturation monitor) monitoring will be continuous and this is displayed and recorded continuously. The lowest recorded oxygen saturation during the time from completion of routine pre-oxygenation until 5 minutes after successful tracheal intubation will be the numerical data point recorded.
Secondary outcome [1] 323078 0
Pre-oxygenation group - Comfort level of the standard face mask and the high flow nasal cannuale assessed using a 5-Point Likert Scale.
Timepoint [1] 323078 0
At completion of the study protocol

Eligibility
Key inclusion criteria
Pre-oxygenation group - Pregnant women at term ( greater than or equal to 36 weeks gestation)
Apnoeic oxygenation group - Any pregnant woman undergoing general anaesthesia caesarean section
Minimum age
18 Years
Maximum age
40 Years
Gender
Females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Significant nasal pathology

Study design
Purpose of the study
Prevention
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
N/A
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
N/A
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Other
Other design features
In this prospective study we aim to recruit two groups of women. The first group of women will be those who will electively undertake high flow humidified nasal oxygenation in order to examine this technique in the setting of pre-oxygenation (the Pre-oxygenation group). The second group of women will be those who are undergoing general anaesthesia for caesarean section and will have high flow humidified nasal oxygenation after induction of anaesthesia in the setting of apnoeic oxygenation (the Apnoeic oxygenation group).

To examine the use of high flow humidified nasal oxygenation for pre-oxygenation we aim to determine the FetO2 in 80 term pregnant women at the end of a protocolised pre-oxygenation method with a high flow humidified nasal cannulae system (Optiflow (trademark)). We aim to assess whether this new technique is able to obtain FetO2 of greater than or equal to 90% after three minutes of pre-oxygenation.

To examine the use of high flow humidified nasal oxygenation for apnoeic oxygenation we aim to recruit women undergoing general anaesthesia caesarean section and use our routine pre-oxygenation technique supplemented with high flow nasal oxygenation immediately after pre-oxygenation and during tracheal intubation and measure oxygen saturation levels and times until successful intubation of the trachea.
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
Pre-oxygenation group
A sample of 80 women will be recruited. This is a pragmatic sample size based on the four months (16 weeks) of recruiting by Dr P Tan. It is anticipated that recruitment will take place in hours on weekdays. Approximately 25 women undergo elective caesarean section each week and with an approximate 20% recruitment rate, 80 women will be recruited during this time. [The previous and only study examining pre-oxygenation in pregnant women had a sample size of only 20 women.] Our hypothesis is that end-tidal oxygen values of equal to or greater than 90% can be achieved in at least 80% of term pregnant women after three minutes of oxygenation using high flow humidified nasal oxygenation.

Apnoeic oxygenation group
For the apnoeic oxygenation study it is anticipated that at least 20% of the women undergoing general anaesthesia caesarean section will be recruited to this study over a one year period (30 women). This is based on the following estimates of numbers - approximately 7500 women give birth with a conservative 25% caesarean section rate of which 8% are performed under general anaesthesia. Information about the study protocol will be disseminated within the anaesthetic department and operating theatres, and experience with nasal oxygenation will increase in the department over the first few months of the pre-oxygenation study thereby facilitating participant enrolment in the study. Our hypothesis is that high flow humidified nasal oxygenation can prevent a desaturation (SpO2) value of greater than 92% in 100% of women prior to successful intubation of the trachea

Recruitment
Recruitment status
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)
VIC
Recruitment hospital [1] 5645 0
The Royal Women's Hospital - Parkville

Funding & Sponsors
Funding source category [1] 293428 0
Hospital
Name [1] 293428 0
The Royal Women's Hospital
Address [1] 293428 0
Locked Bag 300, Corner Grattan Street and Flemington Road, Parkville, Victoria, Australia 3052
Country [1] 293428 0
Australia
Primary sponsor type
Hospital
Name
The Royal Women's Hospital
Address
Department of Anaesthesia, The Royal Women’s Hospital,
Locked Bag 300, Corner Grattan Street and Flemington Road, Parkville, Victoria, Australia 3052
Country
Australia
Secondary sponsor category [1] 292247 0
None
Name [1] 292247 0
N/A
Address [1] 292247 0
N/A
Country [1] 292247 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 294872 0
The Royal Women's Hospital Human Research Ethics Committee
Ethics committee address [1] 294872 0
The Royal Women’s Hospital,
Locked Bag 300, Corner Grattan Street and Flemington Road, Parkville, Victoria, Australia 3052
Ethics committee country [1] 294872 0
Australia
Date submitted for ethics approval [1] 294872 0
04/05/2016
Approval date [1] 294872 0
02/08/2016
Ethics approval number [1] 294872 0

Summary
Brief summary
One of the most serious complications of general anaesthesia in pregnant women is hypoxic brain injury and fetal and/or maternal death related to difficulty oxygenating a pregnant woman. This is due to inability of the anaesthetist to intubate the trachea and ventilate a pregnant woman because of the changed anatomy and physiology of pregnant women leading to the known problem of the difficult obstetric airway. The latest obstetric airway management guidelines by the Obstetric Anaesthetists’ Association (OAA) & Difficult Airway Society (DAS) discuss the importance of pre-oxygenation in managing pregnant women undergoing general anaesthesia as it increases oxygen reserve in the lungs during apnoea. The guidelines recommend that the end-tidal oxygen fraction (FetO2) of equal to or greater than 90%, indicating effective lung denitrogentation, should be achieved prior to induction of anaesthesia. The current way anaesthetists pre-oxygenate pregnant women undergoing general anaesthesia is to use a tight fitting face mask to deliver 100% inspired oxygen. The new guideline also states an alternative method. The guidelines states that nasal oxygenation, to facilitate bulk flow of oxygen to the alveoli could be considered as part of
1. Pre-oxygenation - A pre-oxygenation method and
2. Apnoeic oxygenation - A technique to increase apnoeic time.
The guideline suggests that the anaesthetist should consider attaching nasal cannulae with 5 l.min-1 oxygen flow before starting pre-oxygenation, to maintain bulk flow of oxygen (O2) during intubation attempts, or attach nasal oxygenation after pre-oxygenation during the apnoeic period. There is also mention of humidified high flow nasal oxygenation however no data exists in pregnant women as to its safety or efficacy or acceptability by pregnant women. It is possible that a new pre-oxygenation technique, using high flow humidified nasal oxygen, may have an application in pregnant women however before this new pre-oxygenation technique is considered, it should be equivalent (at least) to the current available technique in terms of safety and efficacy i.e. be able to obtain FetO2 of at least 90% after three minutes of pre-oxygenation. Currently there are no studies reporting FetO2 values in pregnant women with high-flow humidified nasal oxygen delivery systems and no studies reporting the use of nasal high flow oxygen to increase apnoea times therefore it is unclear whether humidified high flow nasal oxygenation, is safe and beneficial in pregnant women.

In this prospective study we aim to recruit two groups of women. The first group of women will be those who will electively undertake high flow humidified nasal oxygenation in order to examine this technique in the setting of pre-oxygenation (Pre-oxygenation group). The second group of women will be those who are undergoing general anaesthesia for caesarean section and will have high flow humidified nasal oxygenation after induction of anaesthesia.
Trial website
N/A
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 65306 0
A/Prof Alicia Dennis
Address 65306 0
Department of Anaesthesia, The Royal Women’s Hospital,
Locked Bag 300, Corner Grattan Street and Flemington Road, Parkville, Victoria, Australia 3052
Country 65306 0
Australia
Phone 65306 0
+61 3 8345 2381
Fax 65306 0
+61 3 8345 2379
Email 65306 0
alicia.dennis@thewomens.org.au
Contact person for public queries
Name 65307 0
A/Prof Alicia Dennis
Address 65307 0
Department of Anaesthesia, The Royal Women’s Hospital,
Locked Bag 300, Corner Grattan Street and Flemington Road, Parkville, Victoria, Australia 3052
Country 65307 0
Australia
Phone 65307 0
+61 3 8345 2381
Fax 65307 0
+61 3 8345 2379
Email 65307 0
alicia.dennis@thewomens.org.au
Contact person for scientific queries
Name 65308 0
A/Prof Alicia Dennis
Address 65308 0
Department of Anaesthesia, The Royal Women’s Hospital,
Locked Bag 300, Corner Grattan Street and Flemington Road, Parkville, Victoria, Australia 3052
Country 65308 0
Australia
Phone 65308 0
+61 3 8345 2381
Fax 65308 0
+61 3 8345 2379
Email 65308 0
alicia.dennis@thewomens.org.au

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