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Trial registered on ANZCTR


Registration number
ACTRN12625000251426
Ethics application status
Approved
Date submitted
11/02/2025
Date registered
7/04/2025
Date last updated
7/04/2025
Date data sharing statement initially provided
7/04/2025
Type of registration
Prospectively registered

Titles & IDs
Public title
Short term haemodynamic effects of high flow humidified nasal oxygen in pregnant people with hypertension – a pilot study
Scientific title
Short term haemodynamic effects of high flow humidified nasal oxygen in pregnant people with hypertension – a pilot study
Secondary ID [1] 313830 0
None
Universal Trial Number (UTN)
U111-1318-2345
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Pregnancy 336639 0
Gestational Hypertension 336640 0
Preeclampsia 336641 0
Condition category
Condition code
Anaesthesiology 333136 333136 0 0
Anaesthetics
Reproductive Health and Childbirth 333137 333137 0 0
Fetal medicine and complications of pregnancy
Cardiovascular 333138 333138 0 0
Hypertension

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Intervention: High flow nasal air for 10 minutes.

High flow humidified nasal oxygen (HFNO) will be applied via the Airvo 2 (Fisher & Paykel, New Zealand) machine using Optiflow (Opt944) nasal cannulae. It will be commenced at a flow of 30 litres/min and an inspired fraction of oxygen of 21% (i.e. room air). After 30 seconds, the flow rate will then be increased to 50 litres/min. The flow rate will be decreased step-wise by 10 litres/min (i.e 50 to 40 to 30 litres/min) if the participant complains of discomfort to a minimum of 30 litres/min after which the study protocol will be abandoned. Flow rate reduction will occur (if required) after the participant is allowed 30 seconds at that flow rate level. Commencement and titration will be performed by principal investigator (specialist anaesthetist) who will be present throughout the protocol to also monitor adherence.

After ten minutes of HFNO, three blood pressure measurements will be recorded, each after 15 seconds of the previous. The average systolic, diastolic and mean blood pressure values will be calculated. Post-protocol fetal heart rate measurement will occur at the earliest practical time point after maternal vital signs are recorded.
Intervention code [1] 330529 0
Treatment: Other
Comparator / control treatment
No control group
Control group
Uncontrolled

Outcomes
Primary outcome [1] 340695 0
Systolic blood pressure
Assessment method [1] 340695 0
Automated oscillometric non-invasive blood pressure cuff on portable Philips MX450 vitals monitor
Timepoint [1] 340695 0
At rest and at 10 minutes on high flow nasal oxygen. Post-protocol measurements: Three blood pressure measurements will be recorded, each after 15 seconds of the previous. The average systolic, diastolic and mean blood pressure values will be calculated.
Secondary outcome [1] 444815 0
Diastolic blood pressure
Assessment method [1] 444815 0
Automated oscillometric non-invasive blood pressure cuff on portable Philips MX450 vitals monitor
Timepoint [1] 444815 0
At rest and at 10 minutes on high flow nasal oxygen Post-protocol measurements: Three blood pressure measurements will be recorded, each after 15 seconds of the previous. The average systolic, diastolic and mean blood pressure values will be calculated.
Secondary outcome [2] 444816 0
Mean arterial blood pressure
Assessment method [2] 444816 0
Automated oscillometric non-invasive blood pressure cuff on portable Philips MX450 vitals monitor
Timepoint [2] 444816 0
At rest and at 10 minutes on high flow nasal oxygen Post-protocol measurements: Three blood pressure measurements will be recorded, each after 15 seconds of the previous. The average systolic, diastolic and mean blood pressure values will be calculated.
Secondary outcome [3] 444817 0
Maternal oxygen saturation
Assessment method [3] 444817 0
Pulse oximeter (M1191BL) on portable Philips MX450 vitals monitor
Timepoint [3] 444817 0
At rest and at 10 minutes on high flow nasal oxygen
Secondary outcome [4] 444818 0
Maternal heart rate
Assessment method [4] 444818 0
Pulse oximeter (M1191BL) on portable Philips MX450 vitals monitor
Timepoint [4] 444818 0
At rest and at 10 minutes on high flow nasal oxygen
Secondary outcome [5] 444819 0
Maternal respiratory rate
Assessment method [5] 444819 0
Clinical assessment with stopwatch on smartphone
Timepoint [5] 444819 0
At rest and at 10 minutes on high flow nasal oxygen
Secondary outcome [6] 444822 0
Fetal heart rate
Assessment method [6] 444822 0
Measured using doppler ultrasound (Huntleigh Sonicaid)
Timepoint [6] 444822 0
At rest and after high flow nasal oxygen protocol (once all other physiological measurements completed
Secondary outcome [7] 444840 0
Number of participants able to wear HFNO running at 50 litres/min for the study duration
Assessment method [7] 444840 0
Clinical assessment
Timepoint [7] 444840 0
After the 10 minutes on high flow nasal oxygen
Secondary outcome [8] 444841 0
Comfort score
Assessment method [8] 444841 0
Patient centred five-point word scales
Timepoint [8] 444841 0
After ten minutes of HFNO and physiological measurements completed
Secondary outcome [9] 445350 0
Acceptability score
Assessment method [9] 445350 0
Five point Likert Scale
Timepoint [9] 445350 0
After ten minutes of HFNO and physiological measurements completed
Secondary outcome [10] 445351 0
Flow rate tolerated
Assessment method [10] 445351 0
Recorded as flow rate on AIRVO2 machine screen
Timepoint [10] 445351 0
After ten minutes of HFNO

Eligibility
Key inclusion criteria
Pregnant, obstetric diagnosis of new onset hypertensive disorder of pregnancy (including gestational hypertension, preeclampsia with or without severe features, hypertension for investigation), more than or equal to 20 weeks gestation

Definition
New onset hypertension will be defined as a pregnant patient with new onset hypertension after 20 weeks gestation. Preeclampsia will be defined as new onset sustained hypertension (systolic blood pressure more than or equal to 140 mmHg and /or diastolic blood pressure more than or equal to 90 mmHg), on two occasions at least four hours apart, with evidence of organ dysfunction, commencing after 20 weeks gestation and resolving within three months of delivery. Preeclampsia will be subdivided into preeclampsia without severe features and preeclampsia with severe features. Gestational hypertension will be defined as hypertension (systolic blood pressure more than or equal to 140 mmHg and /or diastolic blood pressure more than or equal to 90 mmHg) without any associated organ dysfunction. If a patient has new onset hypertension that does not meet the definition of preeclampsia or gestational hypertension their diagnosis will be recorded and will be placed in an “other” category
Minimum age
18 Years
Maximum age
No limit
Sex
Females
Can healthy volunteers participate?
No
Key exclusion criteria
Significant nasal pathology, acutely unwell with non-hypertension related cause, recent antihypertensive medication use (not within: 30 minutes of oral or IV labetalol, 60 minutes of oral nifedipine, no exclusion duration for methyldopa), not in labour

Study design
Purpose of the study
Treatment
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
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
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
We referred to previously published data from our study team which demonstrated that a representative sample of pregnant people with preeclampsia had mean (standard deviation) systolic and diastolic blood pressure of 147 (7.8) mmHg and 93 (6.5) mmHg respectively. For this trial, our study team determined a clinically significant difference between baseline and intervention systolic blood pressure would be 10 mmHg. This is a similar premise used in other published work by Prof A Dennis. With type-1 error rate of 0.05 and a type-2 error rate of 0.1, the calculated sample size is 13 participants. Sample size calculation based on the available data for diastolic blood pressure from the same referenced study was also performed. If diastolic blood pressure was used, a smaller sample size of nine participants would be required. It would be ideal that this current trial is powered to detect a true difference in both systolic and diastolic blood pressure, so we have elected to go by the larger sample size of the two. In order to adequately assess other feasibility aims as well as accounting for potential drop-out from non-tolerance of HFNO, we propose a target sample size of 30 participants.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
14/04/2025
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
30
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
VIC

Funding & Sponsors
Funding source category [1] 318300 0
Charities/Societies/Foundations
Name [1] 318300 0
Australian Society of Anaesthetists (ASA)
Country [1] 318300 0
Australia
Funding source category [2] 318575 0
Commercial sector/Industry
Name [2] 318575 0
Fisher & Paykel Healthcare
Country [2] 318575 0
New Zealand
Primary sponsor type
Individual
Name
Patrick Tan - Royal Women's Hospital
Country
Australia
Secondary sponsor category [1] 320684 0
None
Name [1] 320684 0
Country [1] 320684 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 316937 0
The Royal Melbourne Hospital Human Research Ethics Committee
Ethics committee address [1] 316937 0
Ethics committee country [1] 316937 0
Australia
Date submitted for ethics approval [1] 316937 0
28/01/2025
Approval date [1] 316937 0
02/04/2025
Ethics approval number [1] 316937 0
HREC/115966/MH-2025

Summary
Brief summary
Trial website
Public notes

Contacts
Principal investigator
Name 139486 0
Dr Patrick Tan
Address 139486 0
Department of Anaesthesia, The Royal Women's Hospital 20 Flemington Road, Parkville VIC 3052
Country 139486 0
Australia
Phone 139486 0
+61 3 8345 2381
Email 139486 0
patrickcheefei.tan@thewomens.org.au
Contact person for public queries
Name 139487 0
Patrick Tan
Address 139487 0
Department of Anaesthesia, The Royal Women's Hospital 20 Flemington Road, Parkville VIC 3052
Country 139487 0
Australia
Phone 139487 0
+61 3 8345 2381
Email 139487 0
patrickcheefei.tan@thewomens.org.au
Contact person for scientific queries
Name 139488 0
Patrick Tan
Address 139488 0
Department of Anaesthesia, The Royal Women's Hospital 20 Flemington Road, Parkville VIC 3052
Country 139488 0
Australia
Phone 139488 0
+61 3 8345 2381
Email 139488 0
patrickcheefei.tan@thewomens.org.au

Data sharing statement
Will the study consider sharing individual participant data?
Yes
Will there be any conditions when requesting access to individual participant data?
Persons/groups eligible to request access:
• Researchers
Conditions for requesting access:
• Yes, conditions apply:
• Requires review on a case-by-case basis by the trial custodian, sponsor or data sharing committee
• Requires a data sharing agreement between data requester and trial custodian or sponsor
What individual participant data might be shared?
• De-identified individual participant data:
• All outcomes data
• Published results
What types of analyses could be done with individual participant data?
• Any type of analysis (i.e. no restrictions on data re-use)
When can requests for individual participant data be made (start and end dates)?
From:
After publication of main results
To:
Not yet decided
Where can requests to access individual participant data be made, or data be obtained directly?
• Email of trial custodian, sponsor or committee: Principal Investigator Email: patrickcheefei.tan@thewomens.org.au

Are there extra considerations when requesting access to individual participant data?
No


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.